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Diterpenes from the timber of 20 Erythroxylum species
Phytochemistry, Vol.32,No. 4, pp. 953-959.1993
0031 9422/93 %6.00+0.00 G 1993 PergamonPress Ltd
Printedin Great Britain.
DITERPENES
FROM THE TIMBER OF 20 ER YTHROX YLUM SPECIES STEVEN M. ANSELL, KARL H. PEGEL
and
DAVID A. H. TAYLOR
Department of Chemistry, University of Natal, King George V Avenue, Durban 4001, South Africa (Received 26 May 1992)
Key Word Index-Erythroxylum species; Erythroxylaceae; timber; diterpenes; beyerane; devadarane; dolabrane; kaurane; pictane; pimarane; rosane.
Abstract-Timber extracts of 20 species of Erythroxylum have been examined, yielding 31 known compounds and 12 new compounds which have been identified. Erythroxylum brevipes, E. cuneifolium, E. minutifolium, E. neocalidonicum, E. myrsinites and E. sp. nov. Guaricipo. did not appear to contain diterpenes, but only long-chain aliphatic material, which was not investigated. A preliminary investigation was made of E. ecarinatum (similar to E. pictum), E. ellipticum, (similar to E. australe), and E. rufum (unidentified diterpenes) but was not extended, due to shortage of material.
INTRODUCTION In continuation of our work on Erythroxylum species, we have investigated 20 further species, 14 with adequate samples, and six in a preliminary fashion, due to small sample size. We find diterpenes in 10 of the 14, which are described, and indications of diterpenes in three of the six. The majority of the diterpenes isolated were known compounds, many we had previously found in E. australe [l] or E. pictum [Z], but 12 new compounds were also isolated and identified.
R’ 32H 33 OAc 34H
R
R2 IJI H, 0
35 36
H OH
REFXLTS AND DISCUSSION
The 20 species of Erythroxylum examined in this study were: E. areolatum, E. argentinum, E. brevipes, E.
R’
cuneatum, E. cunefolium, E. deciduum, E. delagoense, E. emarginatum, E. macrocarpum, E. microphyllum, E. minutifolium, E. myrsinites, E. neocalidonium, E. rotundifolium, E. sideroxyloides, E. zambesiacum and E. sp. nov. Guacicipo. The 31 known diterpenes isolated were as follows:
ent-labda-8(17),13E-diene-15,16-diol (1) [3], ent-lipacetoxydevadaran-15&16-diol(2) [4], ent-labda-8(17),14dien-13R-ol (3) [S], ent-labda-8(17),13E-dien-15-01 (4) [6], ent-13R-hydroxylabda-8(17)-dien-3-one (5) [2], entlabda-8(17),14-diene-3B,13R-diol (6) [2], ent-labda8(17),14-diene-13R,18-diol (7) [2], ent-rosan-5B,15<,16trio1 (8) [Z], ent-devadaran-15&16-diol (9) [7J entdevadaran-1 lb,l5&16-trio1 (10) [4], ent-devadaran1/?,11~,15~,16-tetrol (11) [Z], ent-l/?-acetoxydevadaran11~,15~,16-trio1 (12) [2], ent-dolabr-4(18)-en-15&16-diol (13) [2] ent-5cr-dolabr-4(18)-en-15S,16-diol (14) [2], entdolabr-4(18)-en-7c(,15R,16-triol(l5) [Z], ent-dolabr-4(18)en-7u-15S-16-trio1 (16) [2], ent-15[,16-dihydroxypict4(18)-en-5-one (17) [2], ent-beyer-15-ene (18) [S], ent15,16_epoxybeyerane (19) [8, 91, ent-beyer-15-en-17-01 953
OH
.,
= ’ “,
H 8
31 38 39 40
R’ H OH OAc OH
R* 0 H2 H, H,aOAc
H
R’
/) Rl
R*
41 OH Hz 42H 0
954
S. M. ANSELL et al.
(20) [8], enr-beyer-15-en-19-01 (21) [S], ent-beyer-15enl-one (22) [2], ent-17-hydroxybeyer-Sen-l-one (23) [Z], ent-2fl,19-dihydroxybeyer-15-en-l-one (24) [l], ent-2/L 17-dihydroxybeyer-15-en-l-one (25) [2], ent-lb,l9dihydroxybeyer-15-en-2-one (26) Cl], ent-lg,l7-dihydroxybeyer- 15en-2-one (27) [2], ent-2,19_dihydroxybeyer2,15-dien-l-one (28) Cl], ent-2,17-dihydroxybeyer-2,15dien-l-one (29) [2], ent-kauran-16fi-ol (30) [lo] and entkauran-16P,17-diol (31) [lo]. The distribution of these, and of the new compounds, in the species investigated was as follows: E. areolatum, 3, 8, 10.12,17 and 23. E. argentinum, 1, 13,14,20,22,23,29 and 42; E. cuneatum, 3,5,6,8,17,35 and 36; E. deciduum, 4; E. delagoense, 6, 13. 14 and 17; E. macrocarpum, 9, 10, 13, 38 and 39; E. microphyllum, 17, 23-26, 28 and 29; E. rotundifolium, 3,5,7,13,17,20,22,23,25,27,31 and 42; E. sideroxyloides, 2, S-13, 15, 374, E. zambesiacum, 4, 8, 17-22, 32-34,41 and 43.
Rosane derivatives Compound 32, C,,H,,O,, [cr]o-- 2”, (CH,Cl,), needles, mp 123-135” (hexane) had a trisubstituted double bond, four tertiary methyl groups and a 1,2-glycol. It was considered likely that it was a rosane derivative. In agreement with this, treatment with formic acid gave the known ent-ros-5(10)-ene-15<,16-diol diformate [2]. This has a ditertiary double bond, hence formic acid treatment has migrated the original double bond in 32. The acetonide of the 5-ene has been reported [4], and does not correspond to the acetonide of 32, so it would seem that 32 is the l(10) isomer. Oxidation of 32 with perbenzoic acid gave an oxide, leading to a glycol, which was oxidized further to a hydroxy ketone. This does not dehydrate, so the C-10 hydroxyl is presumably p, cis to the C-5 hydrogen. Borohydride reduction of the hydroxy ketone gives the epimeric, cis-glycol, while acid treatment of the epoxide gives the 1(10),5-diene. We assign 32 the structure of ent-5a-ros-l(lO)-en-15&16-diol. Compound 33, C,,H,,O,, [alo + lo” (CH,Cl,), was a gum. The ‘H NMR spectrum showed four tertiary methyl groups, a trisubstituted double bond, a secondary acetoxyl group, and an isolated 1,2-glycol. In general, the spectrum was very similar to that of 32, suggesting that it was an acetoxy derivative. Hydrolysis of the acetate, protection of the diol as an acetonide, oxidation with Jones’ reagent and reduction with hydrazine gave compound 32, confirming this suggestion. The acetoxymethine proton gave rise to a resonance showing that it was axial and adjacent to an unsubstituted methylene group. This is only possible at C-3, C-l 1 or C-12. In the ketone, the adjacent methylene group gave rise to a pair of doublets, not further coupled, eliminating C-3. An equatorial 1 l-acetate group would be expected to shift the H-l resonance downfield, while a 1Zacetate would not. A downfield shift of 0.2 ppm was observed, and there is a similar effect (+ 4.3 ppm) in the 13C NMR. We thus assign 33 the structure ent-ll/&acetoxy-5a-rosl(lO)-en-15<,16-diol.
Compound 34, CZ0H3,0, [or],+23” was a gum. The ‘H NMR spectrum showed four tertiary methyl groups, a vinyl group, and a trisubstituted double bond conjugated to a carbonyl group. The unsaturated ketone was also evidenced by the IR (v,,,_ 1660 cm-‘) and UV &,, 243 nm, E9 x 103) spectra. A pair of doublets (5 2.12,2.38, J= 15.6 Hz) indicates an isolated methylene adjacent to the ketone. This suggests that 34 is ent-2-oxo-ros1(10),15_diene, but this has not been confirmed, due to the small amount available. Pimarane derivatives Compound 35, C,,H,,O, [a&-93” (CH2C12), was isolated as needles mp 122-123” (hexane). The ‘H NMR spectrum showed four tertiary methyl groups, a secondary hydroxyl group, a vinyl group, and an isolated trisubstituted double bond. These observations were confirmed but not extended by the 13C NMR. The four methyl groups suggest a rosane, pimarane, or beyerane skeleton, the other common nuclei having only three. Oxidation gave the derived ketone, which on hydrazine reduction gave a compound whose spectroscopic properties were identical with those reported for ent-pimara8(14),15-diene [lo], although the optical rotation was considerably different, {[a&,--68” (CH,Cl,), as against a reported -101” (CHCI,)), however, it was of the same sign, and therefore of the same em configuration. The methylene adjacent to the carbonyl group in the ketone showed coupling to another methylene, which indicates the ketone is at C-l or C-3, comparison of the 13CNMR spectrum of 35 with that reported for entpimara-8( 14),15-diene [ 1 l] showed that the largest shifts occurred around C-3. so that 35 is a 3-hydroxy derivative. The coupling constants in’ the acetate indicate an equatorial hydroxy group, hence 35 is ent-pimara-8(14),15dien-3/?-ol. This compound has already been recorded [12] with different properties, but the report was erroneous, though persisting in review articles, and has been corrected [ 131, the previous compound being actually the 7,15-diene. Compound (36) was isolated as a diacetate, C,,H,,O,, [@In-63”, (CH,Cl,), mp 105-l lo” (MeOH). Hydrolysis gave the diol 35, [a],-163” (CH,CI,), mp 125-130’ (hexane). The ‘HNMR spectrum showed four tertiary methyl groups, a vinyl group, an isolated trisubstituted double bond and a pair of secondary hydroxy groups, both of which appeared to be equatorial. Oxidation with Jones’ reagent gave a diketone, which on hydrazine reduction gave the same hydrocarbon as 35. Partial hydrolysis of the diacetate gave a hydroxyacetate, in which the hydroxyl was vicinal to a methylene group, while the acetoxymethine proton was coupled to three other protons. This suggests an acetate at C-11 or C-6. Comparison of the 13C NMR spectra for 35 and for the diacetate of 36 show that the second acetoxyl does not affect C-5, while C-9 is deshielded, suggesting that the acetoxyl is at C-11. Further, the resonances of C-4, C-18 and C-9 in the diacetate compared to those in the spectrum of ent-pimaradiene are affected in the same way
Diterpenes from Erythroxylumspp. as those in the spectrum of 35, consequently the present compound is also a 3/Galcohol, and we propose the structure of ent-3b,lla-dihydroxypimara-8(14),1Sdiene.
ial. We therefore propose the structure acetoxydolabr-4(18)-ene-11/?,15&16-triol.
955 ent-l/I-
Beyerane derivatives Dolabrane derivatives
Compound 37, C,,H,,O,, [cr],,+Zo” (CH,Cl,), formed needles mp 143-144” (hexane). The ‘H NMR spectrum showed the presence of three tertiary methyl groups, an isolated 1,Zglycol system, an exocyclic methylene, and a carbonyl group; an acetonide was formed with acetone containing perchloric acid. The exocyclic methylene suggested that the compound might be a dolabrane derivative. The location of the carbonyl group could be determined by comparing the C-8 and C-10 resonances, which can be assigned with confidence, in the acetonide with those in the deoxoderivative, erythroxydiol Y. The resonance due to C-10 is shifted by the influence of the carbonyl group from 656.5 to 65.9, while that due to C-8 is only shifted from 642.1 to 41.6. We, therefore, consider that the 0x0 group is at C-l, and assign 37 the structure ent15<,16-dihydroxydolabr-4(18)-en-l-one. Compound 38, C,,H,,O,, [cl&, + 19” (CH,C&) remained amorphous. The ‘HNMR spectrum indicated the presence of three tertiary methyl groups, an isolated 1,2-glycol, a vinylidene group and a secondary hydroxyl group. This again suggested a dolabrane derivative, the coupling of the hydroxymethine proton showed it to be axial and coupled to two other protons, axial and equatorial. This, in a dolabrane, suggests location at C-3, C-6, C-l or C-12. Oxidation of the acetonide gave a ketone, the protons adjacent to the carbonyl formed an isolated pair of doublets (62.96, 1.75, J= 12.8 Hz), which eliminates C-3 and C-6. The position of the hydroxy was determined from the ’ 3C NMR data of the triacetate, in which C-l was deshielded (+ 2.5 ppm) and C-20 shielded (-3.4 ppm) relative to the positions in the acetate of erythroxydiol Y. This shows that the acetate is equatorial at C-11, and the compound is therefore assigned the structure of ent-dolabr-4(18)-ene-11/?,15&16-triol. Compound 39, [a&-3” (CH,Cl& mp 108-112 (hexane) was readily recognised as the 11-monoacetate of 38, acetylation gave 38 triacetate, hydrolysis gave 38. Compound 40 was isolated as the acetonide, Cz5H4,,05, [E]~ 57” (CH,Cl,) after treatment of crude fractions with acetone and perchloric acid. The ‘H NMR spectrum of the acetonide showed three tertiary methyl groups, an isolated l,Zglycol, a secondary hydroxyl group, a secondary acetoxyl group, and a vinylidene group. Oxidation with Jones’ reagent gave a carbonyl compound, in which an additional doublet resonance (62.96, J = 12.3 Hz) was observed, suggesting an isolated methylene group next to the ketone, although the other half of the doublet was not found. This implies a location at C-11 or C-12. The acetoxymethine proton in the ketone was deshielded by the keto group (65.94: shifted to 85.64); suggesting that the ketone is at C-l 1 and the acetoxy at C-l, in the unique l-11 relationship. The acetoxy is shown by the coupling to be axial, the hydroxy equator-
Compound 41, [aID + 1” (CH,Cl,), was a gum. The acetate, Cz2H3.+02, [aID -56”, (CH,Cl,), had mp 114-l 16” (MeOH). The ‘H NMR spectrum showed four tertiary methyl groups, a secondary acetoxy group and a cis-substituted double bond. (65.53,5.81, J= 5.7 Hz). The four methyl groups and cis double bond suggest a beyerene skeleton. Comparison of the 13C NMR spectrum with that of the suspected parent compound, beyerene [l] showed that the resonance positions of the carbon atoms in rings A and B were little affected, suggesting an acetoxy group at C-l 1 or 12. An 11-acetoxy group would affect the resonance of C-l, and would be expected also to deshield C-9. This has not happened, C-9 is shielded rather than deshielded, being shifted from 653.0 to 49.2 in the acetate. This effect might be expected for an axial C-12 acetoxy group, which would produce a strong y-gauche effect at the axial H-9. Therefore, it appears that the acetoxyl is at C-12. This effect has been calculated for simple beyerene derivatives [14], and the spectra predicted with considerable accuracy. Hydrolysis of the acetate gave the corresponding alcohol, which was oxidised to a ketone, [aID -341” (CH,Cl,). This extremely large rotation change appears to be characteristic of 12-0~0 compounds in ent-beyerene derivatives [15]. We, therefore, assign the structure of entbeyer-15-en-12-01. Compound 42, C,,H,,O, [a&, -12” (CH,Cl,) formed needles mp 152-154” (MeOH). T’he ‘HNMR spectrum showed the presence of four tertiary methyl groups, and two vinyl protons (65.57), the IR and 13CNMR showed the presence of a carbonyl group. Borohydride reduction gave a hydroxy compound in which the two proton signal at 65.57 was transformed to the more usual AB quartet of beyerene derivatives. The 7position is indicated for the ketone, because of its proximity to the double bond. Acetylation gave an acetate with the acetoxymethine proton showing the ABX multiplet typical of an equatorial acetate group. In beyerene, this is only possible at C-7 or C-12. The latter possibility was ruled out by comparison with the ketone derived from 41, in which the 12-ketone does not affect the resonance of the double bond protons, which still appear as the usual quartet. We, therefore, assign 42 the structure ent-beyer15-en-7-one. Compound 43 was isolated as an unstable oil, [aID +28”. The ‘H NMR spectrum showed three tertiary methyl groups, an aldehyde, and a cis-double bond. The instability of the compound suggested an axial aldehyde, i.e. at C-13 or C-19, as these are known to autoxidise readily. Oxidation of ent-19-hydroxybeyer-15-ene with Collins’ reagent gave an aldehyde identical with 43, thus confirming the structure as ent-beyer-15-en-19-al. The aldehyde was unstable to light and to air, degrading within a few days to a mixture of three major components, which were not further investigated.
33-AC
121.6 21.8 35.2 31.2 32.0 24.6 23.3 41.3 42.1 144.9 75.0 34.4 37.5 35.8 78.5 62.8 23.2 20.4 28.7 14.3 20.7, 170.2 21.4, 170.5 20.8, 170.7
32
117.3 19.2 35.2 31.4 31.4 26.2 23.1 42.9 37.0 148.7 37.4 29.9 37.0 37.8 81.5 62.7 18.4 20.8 29.6 19.7
C
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Acetate Acetate Acetate Acetonide 31.1 25.1 17.9 44.8 38.6 175.2 39.9 32.7 36.7 34.3 122.8 109.2 22.3 20.0 28.9 22.3
150.6 200.0 53.6
34 37.3 27.7 79.2 39.1 54.3 22.3 35.8 137.9 51.3 38.3 19.2 35.8 38.6 128.3 147.3 112.8 29.5 28.5 15.7 14.8
35 23.8 28.6 35.3 159.7 41.0 37.6 25.5 41.0 42.0 55.8 78.2 32.7 37.0 36.6 79.4 62.8 20.0 102.7 21.7 9.0 20.7, 170.1 20.8, 170.1 21.7, 170.5
211.0 43.5 34.2 156.0 43.6 38.0 25.6 41.6 36.3 65.9 32.7 27.8 35.4 35.2 84.7 64.6 19.5 105.8 23.8 12.4
36.5 24.0 80.6 39.4 54.0 22.4 35.6 136.4 55.4 38.0 69.3 40.1 38.7 128.4 145.4 112.5 29.5 28.3 15.7 16.6 21.5, 170.6 21.1, 170.2 25.1, 26.3 108.6
~&AC,
37 acetonide
&AC,
Table 1. ‘“C NMR spectra1 data for compounds 32-38, and 40-42
25.1, 25.1 108.7
75.5 33.4 28.4 159.7 41.3 39.5 25.8 42.0 44.1 57.8 73.4 39.2 36.2 35.7 84.1 64.5 20.3 103.3 24.6 8.9 21.8, 170.3
40AC acetonide 39.1 18.5 42.2 33.2 56.1 20.2 36.9 49.2 49.2 37.0 26.9 73.4 47.3 54.3 138.6 135.9 21.2 33.7 21.9 14.3 21.4, -
41-AC 38.9 18.4 41.0 33.3 54.3 38.0 219.6 63.0 53.3 37.3 18.2 32.3 44.4 54.1 138.3 130.6 24.2 33.0 21.4 14.6
42
958
S. M.
ANSELL
-i-24” (CH,Cl,); ‘H NMR: 64.80 (lH, br s, II-18a), 4.76 (iH, br s, H-18b), 2.13 (lH, s, H-IO), 1.4, 1.34 (An), 1.12, 1.08, 0.89 (3 x Me). ent-~o~~~r-ql8)-en-l1~,15~,16”~~~#~ (38). Amorphous powder from aq. MeOH [y&19’ (CH,Cl,); ‘H NMR: 64.49 (2H, br s, 2H-18), 1.08, 0.94, 0.82 (3 x Me). Treatment with Me&U and perchloric acid as described for 37 gave the acetonide, mp 154-155” (hexane), [aln+53” (CH,Cl,); ‘H NMR: 64.49 (2H, d, J= 1.7 Hz, 2H-18), 3.5 (lH, m, J = 7 Hz, H-l l), 1.40, 1.33 (An), 1.07,0.93,0.82 (3 x Me). Acetylation gave the ll-acetate as a gum, [@In +3” (CH,CI,); ‘H NMR: 64.75 (lH, t, J=8.2 Hz, H-11), 4.49 (2H, d, J = 1.1 Hz, 2H-18), 1.98 (OAc), 1.4Ql.33 (An), 1.07, 0.97, 0.92 (3 x Me). Oxidation of this hydroxyacetonide (0.15 g) gave the Xl-ketone (O.l2g), mp 130-131” (MeOH); [a]n +155” (CH,Cl,); ‘HNMR: 64.48 (2N, br s, 2H-18), 2.96 (lH, d, J= 12.8 Hz, H-12a), 1.75(1H,dd,5=12.8, 1.8 Hz, H-12b), 1.41, 1.36(An), 1.18, 1.09, 0.85 (3 x Me). Acetylation of 38 gave a gummy triacetate, [E],,-26” (CH,CI,); ‘H NMR: 64.86 (iH, dd, 5=8.7, 2.6 Hz, H-15), 4.69 (IH, t, J=8.2 Hz, H-11), 4.48 (2H, br s, 2H-18), 4.35 (lH, dd, J=t1,8, 2.6 Hz, H-16a), 3.94 (lH, dd, 1=11.7, 8.8 Hz, H-16b), 2.06, 1.99, 1.97 (3 x OAc), 1.07, 1.06, 0.90 (3 x Me). ent-1 l~-~ce~~x~~o~~~r-4(18)-en-l5~,16-d~o~ (39). Needles, mp 108-l 12” (hexane), [IX&,- 3” (CH,Cl,); ‘H NMR: 64.72(1H,t,J=8.1 Hz,H-11),4.47(2H, brs,2H-18), 1.97 (OAc), 1.06,0.98,0.91 (3 x Me). Hydrolysis gave the trio1 38, acetyiation gave the triacetate. ent-1~-~ce~ox~~~o~~br-~18)-e~-11/3,15~,16-triol (4% Isolated as the acetonide by treating the crude trioi with Me,CO and perchloric acid. It remained gummy; [a& + 57” (CH,Cl,): ‘H NMR: 65.96 (lH, br d, J = 2.8 Hz, HI), 4.56 (IH, br s, H-18), 2.06 (OAc), 1.39, 1.03, 0.92 (3 x Me). Oxidation of the acetonide with Jones’ reagent gave the 11-keto derivative, also a gum, ‘H NMR: 65.64, (IH, br s, H-l), 4.61 (19 br s, H-l$a), 4.55 (IH, br s, H18b), 2.96 (lH, d, J= 12.3 Hz, H-12), 2.04 (OAc), 1.42, 1.36 (An), 1.42, 1.29, 0.84 (3 x Me). ent-Beyer-15-en-12a-ol (41). Isolated as a gum [@Jn + I”, (Found m/z 288.2444. Calc. for C,,H,,O: 288.2453); ‘HNMR: 65.7 (lH, d, J=5.6 Hz, H-16), 5.54 (LH, d, J =5.6 Hz, H-15), 3.67(lH,m, 5 lines, separation 1.8 Hz, H12), 1.06, 0.87, 0.83, 0.70 (4x Me). The acetate had mp 114-l 16L(MeOH), [xl,, - 56” (C&Cl,); ‘H NMR: 65.81 (lH, d, j=5.7 Hz, H-16), 5.53 (lH, d, f=5.6 Hz, H-15), 4.84(lH, m, J= 1.9 Hz, H-12), 2.05 @AC), 0.98,0.87,0.82, 0.69 (4 x Me). Compound 41 (15 mg) in Me,CO was oxidized with Jones’ reagent, the ketone was obtained as a gum (II mg), [~l]n--341” (CH,Cl,); IR v,,, 17lOcm-I: ‘H NMR: 66.05 (IH, d, 5=5.5 Hz, H-16), 5.57 (lH, d, J =5.3 Hz, H-15), 1.08, 0.87, 0.83, 0.76 (4 x Me). ent-Beyer- 15-en-7-one (42). Needles, mp 152-l 54” (MeOH), [y.&, -12” (CH,CI,); (Found m/z 286.2290, &,H,,O requires: 286.2297). ‘H NMR: 65.57 (2H, d, J ~10.6 Hz, H-15, H-16), 1.07, 0.92, 0.86, 0.86 (4x Me). Borohydride reduction of 42 (10 mg) gave ent-beyer- t5en-7-01 (7mg), ‘HNMR:~5.69(lH,d,~=5.6Hz,H-l6)~ 5.56(1H, d, J-5.9 Hz, H-IS), 3.42 (IH, dd, J=ll.l, 5.1
et al.
Hz, H-7), 1.04,0.87,0.84,0.7.5 (4 x Me). The acetate (5 mg) had1HNMR:~5.74(lH,d,~=5.7Hz,H-16),5.47~lH,d, J=5.6Hz,H-15),4.75(lH.dd,J=l0.7,5.3 Hz,H-7),2.12 (OAc), 1.10, 0.97, 0.93, 0.8 (4 x Mel. ent-Beyer-15-en-19-nI (43). Oil, [a&+28” (CH,Cl,); ‘H NMR: 69.97 (lH,.s, H-19), 5.70(1H,d,J=5.6, H-16), 5.47 (lH, d, J-5.8 Hz, H-15), 1.01, 1.01, 0.62 (3xMe), borohydride reduction of 43 (100 mg) gave ent-beyer-15en-19-01 (100 mg), needles mp 116-l 18” (hexane). A soln of beyer-15-en-19-01 (500 mg) in CH,Cl, was oxidised with excess Collins’ reagent, yielding the aldehyde (200 mg) as a semi-crystalline gum. Acknowledgements-We thank the folowing people for the collection of plant material. Dr Caesar Catalan ~Universidad NacionaI de Tucuman, Argentina), Mr Don Nicholson, (Dept. of Forestry, Australia), Mr John Clarkson, (Dept. of Primary Industries, Australia), Dr Amantino Ramos de Freitas (Instituto de Pesquisas Technologicas do Estado de Sao Paulo, Brazil), Dr T. Zanoni (Jardim Botanic0 National, Republica Dominicana), Mr A. Owadally and Mr M. Dull00 (Forestry Service, Mauritius), Dr John de Freitas (Stichting Carambi, Netherlands Antilles), Dr Stephanie La Barre (C.N.R.S., New Caledonia), Dr G. Schmeda Hirschmann, (Universidad Naeional de Ascunscion, Paraguay), Dr John Francis (Dept. of Agriculture, Puerto Rico), Mr Ali Tbrahim (Botanic Gardens, Singapore), Mr L. Powrie (Lowveld Botanic Gardens, RSA), and Dr T. Mutler (National Herbarium, Zimbabwe). We thank Dr. M. Bokel (University of Hohenheim, Stuttgart) for NMR spectra, and Prof. G. Rucker (Bonn University for high resolution mass spectra. SMA is grateful to the CSIR for a maintenance grant.
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Ansell, S. M., Pegel, K. H. and Taylor, D. A. H. (1992) Phytoc~em~srry 32,945.
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6. 7.
8. 9.
Miyamoto, F., Naoki. H.. Naya. Y. and Nakanishi, K. (1980) Tetrahedron 36, 348 1. Connolly, J. D., Gunn, D. M., McCrindle, R., Murray, R. D. H. and Overton, K. H. (1967) J. Chem. Sot.(C) 668. Matsuo, A., Nakayama, M., Ono, J. and Hayashi, S. (1972) &it. Naturforsch. 27B, 1437. C. A. (1973) 78, 69236j. Almqvist, S., Enzell, C. R. and Wehrli, F. W. (1975) Actta Chem. Stand. B29, 695. Connolly, J. D., McCrindle, R., Murray, R. D. H., Renfrew, A. J., Overton, K. H. and Melera, A. (1966) J. Chem. Soc.{C) 268. McCrindle, R.. Martin, A. and Murray, R. D. H. (1968) J. Chem. Soc.f Cj 2349. Martin, A. and Murray, R. D. H. (1968) J. Chem. Sac.[Cj 2529.
Diterpenes
from Erythroxylum
spp.
959
10. Soman, R., Kapadi, A. H., Sobti, R. and Dev, S. (1983) 14. von Cat-stern-Lichterfelde, C. and Pascual, C. Indian J. Chem. 22B, 989. C. A. (1984) 100,210186z. Raband, R. Ma., Rodriguez, B. and Valverde, S. 11. Wenkert, E. and Buckwalter, B. (1972) J. Am. Chem. (1977) Tetrahedron 33, 1989. Sot. 94, 4367. 15. Piacenza, L. P. L., Pegel, K. H., Phillips, L. and 12. Aiyar, V. N., Rao, P. S., Sachdev, G. P. and Seshadri, Waight, E. S. (1979) J. Chem. Sot. Perkin I 1004. T. R. (1969) Indian J. Chem. C. A. (1969) 71,109778b. 13. Aiyar, V. N and Seshadri, T. R. (1971) Indian J. Chem. 9B, 1055. C. A. (1971) 76, 14741.
0031 9422/93 %6.00+0.00 G 1993 PergamonPress Ltd
Printedin Great Britain.
DITERPENES
FROM THE TIMBER OF 20 ER YTHROX YLUM SPECIES STEVEN M. ANSELL, KARL H. PEGEL
and
DAVID A. H. TAYLOR
Department of Chemistry, University of Natal, King George V Avenue, Durban 4001, South Africa (Received 26 May 1992)
Key Word Index-Erythroxylum species; Erythroxylaceae; timber; diterpenes; beyerane; devadarane; dolabrane; kaurane; pictane; pimarane; rosane.
Abstract-Timber extracts of 20 species of Erythroxylum have been examined, yielding 31 known compounds and 12 new compounds which have been identified. Erythroxylum brevipes, E. cuneifolium, E. minutifolium, E. neocalidonicum, E. myrsinites and E. sp. nov. Guaricipo. did not appear to contain diterpenes, but only long-chain aliphatic material, which was not investigated. A preliminary investigation was made of E. ecarinatum (similar to E. pictum), E. ellipticum, (similar to E. australe), and E. rufum (unidentified diterpenes) but was not extended, due to shortage of material.
INTRODUCTION In continuation of our work on Erythroxylum species, we have investigated 20 further species, 14 with adequate samples, and six in a preliminary fashion, due to small sample size. We find diterpenes in 10 of the 14, which are described, and indications of diterpenes in three of the six. The majority of the diterpenes isolated were known compounds, many we had previously found in E. australe [l] or E. pictum [Z], but 12 new compounds were also isolated and identified.
R’ 32H 33 OAc 34H
R
R2 IJI H, 0
35 36
H OH
REFXLTS AND DISCUSSION
The 20 species of Erythroxylum examined in this study were: E. areolatum, E. argentinum, E. brevipes, E.
R’
cuneatum, E. cunefolium, E. deciduum, E. delagoense, E. emarginatum, E. macrocarpum, E. microphyllum, E. minutifolium, E. myrsinites, E. neocalidonium, E. rotundifolium, E. sideroxyloides, E. zambesiacum and E. sp. nov. Guacicipo. The 31 known diterpenes isolated were as follows:
ent-labda-8(17),13E-diene-15,16-diol (1) [3], ent-lipacetoxydevadaran-15&16-diol(2) [4], ent-labda-8(17),14dien-13R-ol (3) [S], ent-labda-8(17),13E-dien-15-01 (4) [6], ent-13R-hydroxylabda-8(17)-dien-3-one (5) [2], entlabda-8(17),14-diene-3B,13R-diol (6) [2], ent-labda8(17),14-diene-13R,18-diol (7) [2], ent-rosan-5B,15<,16trio1 (8) [Z], ent-devadaran-15&16-diol (9) [7J entdevadaran-1 lb,l5&16-trio1 (10) [4], ent-devadaran1/?,11~,15~,16-tetrol (11) [Z], ent-l/?-acetoxydevadaran11~,15~,16-trio1 (12) [2], ent-dolabr-4(18)-en-15&16-diol (13) [2] ent-5cr-dolabr-4(18)-en-15S,16-diol (14) [2], entdolabr-4(18)-en-7c(,15R,16-triol(l5) [Z], ent-dolabr-4(18)en-7u-15S-16-trio1 (16) [2], ent-15[,16-dihydroxypict4(18)-en-5-one (17) [2], ent-beyer-15-ene (18) [S], ent15,16_epoxybeyerane (19) [8, 91, ent-beyer-15-en-17-01 953
OH
.,
= ’ “,
H 8
31 38 39 40
R’ H OH OAc OH
R* 0 H2 H, H,aOAc
H
R’
/) Rl
R*
41 OH Hz 42H 0
954
S. M. ANSELL et al.
(20) [8], enr-beyer-15-en-19-01 (21) [S], ent-beyer-15enl-one (22) [2], ent-17-hydroxybeyer-Sen-l-one (23) [Z], ent-2fl,19-dihydroxybeyer-15-en-l-one (24) [l], ent-2/L 17-dihydroxybeyer-15-en-l-one (25) [2], ent-lb,l9dihydroxybeyer-15-en-2-one (26) Cl], ent-lg,l7-dihydroxybeyer- 15en-2-one (27) [2], ent-2,19_dihydroxybeyer2,15-dien-l-one (28) Cl], ent-2,17-dihydroxybeyer-2,15dien-l-one (29) [2], ent-kauran-16fi-ol (30) [lo] and entkauran-16P,17-diol (31) [lo]. The distribution of these, and of the new compounds, in the species investigated was as follows: E. areolatum, 3, 8, 10.12,17 and 23. E. argentinum, 1, 13,14,20,22,23,29 and 42; E. cuneatum, 3,5,6,8,17,35 and 36; E. deciduum, 4; E. delagoense, 6, 13. 14 and 17; E. macrocarpum, 9, 10, 13, 38 and 39; E. microphyllum, 17, 23-26, 28 and 29; E. rotundifolium, 3,5,7,13,17,20,22,23,25,27,31 and 42; E. sideroxyloides, 2, S-13, 15, 374, E. zambesiacum, 4, 8, 17-22, 32-34,41 and 43.
Rosane derivatives Compound 32, C,,H,,O,, [cr]o-- 2”, (CH,Cl,), needles, mp 123-135” (hexane) had a trisubstituted double bond, four tertiary methyl groups and a 1,2-glycol. It was considered likely that it was a rosane derivative. In agreement with this, treatment with formic acid gave the known ent-ros-5(10)-ene-15<,16-diol diformate [2]. This has a ditertiary double bond, hence formic acid treatment has migrated the original double bond in 32. The acetonide of the 5-ene has been reported [4], and does not correspond to the acetonide of 32, so it would seem that 32 is the l(10) isomer. Oxidation of 32 with perbenzoic acid gave an oxide, leading to a glycol, which was oxidized further to a hydroxy ketone. This does not dehydrate, so the C-10 hydroxyl is presumably p, cis to the C-5 hydrogen. Borohydride reduction of the hydroxy ketone gives the epimeric, cis-glycol, while acid treatment of the epoxide gives the 1(10),5-diene. We assign 32 the structure of ent-5a-ros-l(lO)-en-15&16-diol. Compound 33, C,,H,,O,, [alo + lo” (CH,Cl,), was a gum. The ‘H NMR spectrum showed four tertiary methyl groups, a trisubstituted double bond, a secondary acetoxyl group, and an isolated 1,2-glycol. In general, the spectrum was very similar to that of 32, suggesting that it was an acetoxy derivative. Hydrolysis of the acetate, protection of the diol as an acetonide, oxidation with Jones’ reagent and reduction with hydrazine gave compound 32, confirming this suggestion. The acetoxymethine proton gave rise to a resonance showing that it was axial and adjacent to an unsubstituted methylene group. This is only possible at C-3, C-l 1 or C-12. In the ketone, the adjacent methylene group gave rise to a pair of doublets, not further coupled, eliminating C-3. An equatorial 1 l-acetate group would be expected to shift the H-l resonance downfield, while a 1Zacetate would not. A downfield shift of 0.2 ppm was observed, and there is a similar effect (+ 4.3 ppm) in the 13C NMR. We thus assign 33 the structure ent-ll/&acetoxy-5a-rosl(lO)-en-15<,16-diol.
Compound 34, CZ0H3,0, [or],+23” was a gum. The ‘H NMR spectrum showed four tertiary methyl groups, a vinyl group, and a trisubstituted double bond conjugated to a carbonyl group. The unsaturated ketone was also evidenced by the IR (v,,,_ 1660 cm-‘) and UV &,, 243 nm, E9 x 103) spectra. A pair of doublets (5 2.12,2.38, J= 15.6 Hz) indicates an isolated methylene adjacent to the ketone. This suggests that 34 is ent-2-oxo-ros1(10),15_diene, but this has not been confirmed, due to the small amount available. Pimarane derivatives Compound 35, C,,H,,O, [a&-93” (CH2C12), was isolated as needles mp 122-123” (hexane). The ‘H NMR spectrum showed four tertiary methyl groups, a secondary hydroxyl group, a vinyl group, and an isolated trisubstituted double bond. These observations were confirmed but not extended by the 13C NMR. The four methyl groups suggest a rosane, pimarane, or beyerane skeleton, the other common nuclei having only three. Oxidation gave the derived ketone, which on hydrazine reduction gave a compound whose spectroscopic properties were identical with those reported for ent-pimara8(14),15-diene [lo], although the optical rotation was considerably different, {[a&,--68” (CH,Cl,), as against a reported -101” (CHCI,)), however, it was of the same sign, and therefore of the same em configuration. The methylene adjacent to the carbonyl group in the ketone showed coupling to another methylene, which indicates the ketone is at C-l or C-3, comparison of the 13CNMR spectrum of 35 with that reported for entpimara-8( 14),15-diene [ 1 l] showed that the largest shifts occurred around C-3. so that 35 is a 3-hydroxy derivative. The coupling constants in’ the acetate indicate an equatorial hydroxy group, hence 35 is ent-pimara-8(14),15dien-3/?-ol. This compound has already been recorded [12] with different properties, but the report was erroneous, though persisting in review articles, and has been corrected [ 131, the previous compound being actually the 7,15-diene. Compound (36) was isolated as a diacetate, C,,H,,O,, [@In-63”, (CH,Cl,), mp 105-l lo” (MeOH). Hydrolysis gave the diol 35, [a],-163” (CH,CI,), mp 125-130’ (hexane). The ‘HNMR spectrum showed four tertiary methyl groups, a vinyl group, an isolated trisubstituted double bond and a pair of secondary hydroxy groups, both of which appeared to be equatorial. Oxidation with Jones’ reagent gave a diketone, which on hydrazine reduction gave the same hydrocarbon as 35. Partial hydrolysis of the diacetate gave a hydroxyacetate, in which the hydroxyl was vicinal to a methylene group, while the acetoxymethine proton was coupled to three other protons. This suggests an acetate at C-11 or C-6. Comparison of the 13C NMR spectra for 35 and for the diacetate of 36 show that the second acetoxyl does not affect C-5, while C-9 is deshielded, suggesting that the acetoxyl is at C-11. Further, the resonances of C-4, C-18 and C-9 in the diacetate compared to those in the spectrum of ent-pimaradiene are affected in the same way
Diterpenes from Erythroxylumspp. as those in the spectrum of 35, consequently the present compound is also a 3/Galcohol, and we propose the structure of ent-3b,lla-dihydroxypimara-8(14),1Sdiene.
ial. We therefore propose the structure acetoxydolabr-4(18)-ene-11/?,15&16-triol.
955 ent-l/I-
Beyerane derivatives Dolabrane derivatives
Compound 37, C,,H,,O,, [cr],,+Zo” (CH,Cl,), formed needles mp 143-144” (hexane). The ‘H NMR spectrum showed the presence of three tertiary methyl groups, an isolated 1,Zglycol system, an exocyclic methylene, and a carbonyl group; an acetonide was formed with acetone containing perchloric acid. The exocyclic methylene suggested that the compound might be a dolabrane derivative. The location of the carbonyl group could be determined by comparing the C-8 and C-10 resonances, which can be assigned with confidence, in the acetonide with those in the deoxoderivative, erythroxydiol Y. The resonance due to C-10 is shifted by the influence of the carbonyl group from 656.5 to 65.9, while that due to C-8 is only shifted from 642.1 to 41.6. We, therefore, consider that the 0x0 group is at C-l, and assign 37 the structure ent15<,16-dihydroxydolabr-4(18)-en-l-one. Compound 38, C,,H,,O,, [cl&, + 19” (CH,C&) remained amorphous. The ‘HNMR spectrum indicated the presence of three tertiary methyl groups, an isolated 1,2-glycol, a vinylidene group and a secondary hydroxyl group. This again suggested a dolabrane derivative, the coupling of the hydroxymethine proton showed it to be axial and coupled to two other protons, axial and equatorial. This, in a dolabrane, suggests location at C-3, C-6, C-l or C-12. Oxidation of the acetonide gave a ketone, the protons adjacent to the carbonyl formed an isolated pair of doublets (62.96, 1.75, J= 12.8 Hz), which eliminates C-3 and C-6. The position of the hydroxy was determined from the ’ 3C NMR data of the triacetate, in which C-l was deshielded (+ 2.5 ppm) and C-20 shielded (-3.4 ppm) relative to the positions in the acetate of erythroxydiol Y. This shows that the acetate is equatorial at C-11, and the compound is therefore assigned the structure of ent-dolabr-4(18)-ene-11/?,15&16-triol. Compound 39, [a&-3” (CH,Cl& mp 108-112 (hexane) was readily recognised as the 11-monoacetate of 38, acetylation gave 38 triacetate, hydrolysis gave 38. Compound 40 was isolated as the acetonide, Cz5H4,,05, [E]~ 57” (CH,Cl,) after treatment of crude fractions with acetone and perchloric acid. The ‘H NMR spectrum of the acetonide showed three tertiary methyl groups, an isolated l,Zglycol, a secondary hydroxyl group, a secondary acetoxyl group, and a vinylidene group. Oxidation with Jones’ reagent gave a carbonyl compound, in which an additional doublet resonance (62.96, J = 12.3 Hz) was observed, suggesting an isolated methylene group next to the ketone, although the other half of the doublet was not found. This implies a location at C-11 or C-12. The acetoxymethine proton in the ketone was deshielded by the keto group (65.94: shifted to 85.64); suggesting that the ketone is at C-l 1 and the acetoxy at C-l, in the unique l-11 relationship. The acetoxy is shown by the coupling to be axial, the hydroxy equator-
Compound 41, [aID + 1” (CH,Cl,), was a gum. The acetate, Cz2H3.+02, [aID -56”, (CH,Cl,), had mp 114-l 16” (MeOH). The ‘H NMR spectrum showed four tertiary methyl groups, a secondary acetoxy group and a cis-substituted double bond. (65.53,5.81, J= 5.7 Hz). The four methyl groups and cis double bond suggest a beyerene skeleton. Comparison of the 13C NMR spectrum with that of the suspected parent compound, beyerene [l] showed that the resonance positions of the carbon atoms in rings A and B were little affected, suggesting an acetoxy group at C-l 1 or 12. An 11-acetoxy group would affect the resonance of C-l, and would be expected also to deshield C-9. This has not happened, C-9 is shielded rather than deshielded, being shifted from 653.0 to 49.2 in the acetate. This effect might be expected for an axial C-12 acetoxy group, which would produce a strong y-gauche effect at the axial H-9. Therefore, it appears that the acetoxyl is at C-12. This effect has been calculated for simple beyerene derivatives [14], and the spectra predicted with considerable accuracy. Hydrolysis of the acetate gave the corresponding alcohol, which was oxidised to a ketone, [aID -341” (CH,Cl,). This extremely large rotation change appears to be characteristic of 12-0~0 compounds in ent-beyerene derivatives [15]. We, therefore, assign the structure of entbeyer-15-en-12-01. Compound 42, C,,H,,O, [a&, -12” (CH,Cl,) formed needles mp 152-154” (MeOH). T’he ‘HNMR spectrum showed the presence of four tertiary methyl groups, and two vinyl protons (65.57), the IR and 13CNMR showed the presence of a carbonyl group. Borohydride reduction gave a hydroxy compound in which the two proton signal at 65.57 was transformed to the more usual AB quartet of beyerene derivatives. The 7position is indicated for the ketone, because of its proximity to the double bond. Acetylation gave an acetate with the acetoxymethine proton showing the ABX multiplet typical of an equatorial acetate group. In beyerene, this is only possible at C-7 or C-12. The latter possibility was ruled out by comparison with the ketone derived from 41, in which the 12-ketone does not affect the resonance of the double bond protons, which still appear as the usual quartet. We, therefore, assign 42 the structure ent-beyer15-en-7-one. Compound 43 was isolated as an unstable oil, [aID +28”. The ‘H NMR spectrum showed three tertiary methyl groups, an aldehyde, and a cis-double bond. The instability of the compound suggested an axial aldehyde, i.e. at C-13 or C-19, as these are known to autoxidise readily. Oxidation of ent-19-hydroxybeyer-15-ene with Collins’ reagent gave an aldehyde identical with 43, thus confirming the structure as ent-beyer-15-en-19-al. The aldehyde was unstable to light and to air, degrading within a few days to a mixture of three major components, which were not further investigated.
33-AC
121.6 21.8 35.2 31.2 32.0 24.6 23.3 41.3 42.1 144.9 75.0 34.4 37.5 35.8 78.5 62.8 23.2 20.4 28.7 14.3 20.7, 170.2 21.4, 170.5 20.8, 170.7
32
117.3 19.2 35.2 31.4 31.4 26.2 23.1 42.9 37.0 148.7 37.4 29.9 37.0 37.8 81.5 62.7 18.4 20.8 29.6 19.7
C
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Acetate Acetate Acetate Acetonide 31.1 25.1 17.9 44.8 38.6 175.2 39.9 32.7 36.7 34.3 122.8 109.2 22.3 20.0 28.9 22.3
150.6 200.0 53.6
34 37.3 27.7 79.2 39.1 54.3 22.3 35.8 137.9 51.3 38.3 19.2 35.8 38.6 128.3 147.3 112.8 29.5 28.5 15.7 14.8
35 23.8 28.6 35.3 159.7 41.0 37.6 25.5 41.0 42.0 55.8 78.2 32.7 37.0 36.6 79.4 62.8 20.0 102.7 21.7 9.0 20.7, 170.1 20.8, 170.1 21.7, 170.5
211.0 43.5 34.2 156.0 43.6 38.0 25.6 41.6 36.3 65.9 32.7 27.8 35.4 35.2 84.7 64.6 19.5 105.8 23.8 12.4
36.5 24.0 80.6 39.4 54.0 22.4 35.6 136.4 55.4 38.0 69.3 40.1 38.7 128.4 145.4 112.5 29.5 28.3 15.7 16.6 21.5, 170.6 21.1, 170.2 25.1, 26.3 108.6
~&AC,
37 acetonide
&AC,
Table 1. ‘“C NMR spectra1 data for compounds 32-38, and 40-42
25.1, 25.1 108.7
75.5 33.4 28.4 159.7 41.3 39.5 25.8 42.0 44.1 57.8 73.4 39.2 36.2 35.7 84.1 64.5 20.3 103.3 24.6 8.9 21.8, 170.3
40AC acetonide 39.1 18.5 42.2 33.2 56.1 20.2 36.9 49.2 49.2 37.0 26.9 73.4 47.3 54.3 138.6 135.9 21.2 33.7 21.9 14.3 21.4, -
41-AC 38.9 18.4 41.0 33.3 54.3 38.0 219.6 63.0 53.3 37.3 18.2 32.3 44.4 54.1 138.3 130.6 24.2 33.0 21.4 14.6
42
958
S. M.
ANSELL
-i-24” (CH,Cl,); ‘H NMR: 64.80 (lH, br s, II-18a), 4.76 (iH, br s, H-18b), 2.13 (lH, s, H-IO), 1.4, 1.34 (An), 1.12, 1.08, 0.89 (3 x Me). ent-~o~~~r-ql8)-en-l1~,15~,16”~~~#~ (38). Amorphous powder from aq. MeOH [y&19’ (CH,Cl,); ‘H NMR: 64.49 (2H, br s, 2H-18), 1.08, 0.94, 0.82 (3 x Me). Treatment with Me&U and perchloric acid as described for 37 gave the acetonide, mp 154-155” (hexane), [aln+53” (CH,Cl,); ‘H NMR: 64.49 (2H, d, J= 1.7 Hz, 2H-18), 3.5 (lH, m, J = 7 Hz, H-l l), 1.40, 1.33 (An), 1.07,0.93,0.82 (3 x Me). Acetylation gave the ll-acetate as a gum, [@In +3” (CH,CI,); ‘H NMR: 64.75 (lH, t, J=8.2 Hz, H-11), 4.49 (2H, d, J = 1.1 Hz, 2H-18), 1.98 (OAc), 1.4Ql.33 (An), 1.07, 0.97, 0.92 (3 x Me). Oxidation of this hydroxyacetonide (0.15 g) gave the Xl-ketone (O.l2g), mp 130-131” (MeOH); [a]n +155” (CH,Cl,); ‘HNMR: 64.48 (2N, br s, 2H-18), 2.96 (lH, d, J= 12.8 Hz, H-12a), 1.75(1H,dd,5=12.8, 1.8 Hz, H-12b), 1.41, 1.36(An), 1.18, 1.09, 0.85 (3 x Me). Acetylation of 38 gave a gummy triacetate, [E],,-26” (CH,CI,); ‘H NMR: 64.86 (iH, dd, 5=8.7, 2.6 Hz, H-15), 4.69 (IH, t, J=8.2 Hz, H-11), 4.48 (2H, br s, 2H-18), 4.35 (lH, dd, J=t1,8, 2.6 Hz, H-16a), 3.94 (lH, dd, 1=11.7, 8.8 Hz, H-16b), 2.06, 1.99, 1.97 (3 x OAc), 1.07, 1.06, 0.90 (3 x Me). ent-1 l~-~ce~~x~~o~~~r-4(18)-en-l5~,16-d~o~ (39). Needles, mp 108-l 12” (hexane), [IX&,- 3” (CH,Cl,); ‘H NMR: 64.72(1H,t,J=8.1 Hz,H-11),4.47(2H, brs,2H-18), 1.97 (OAc), 1.06,0.98,0.91 (3 x Me). Hydrolysis gave the trio1 38, acetyiation gave the triacetate. ent-1~-~ce~ox~~~o~~br-~18)-e~-11/3,15~,16-triol (4% Isolated as the acetonide by treating the crude trioi with Me,CO and perchloric acid. It remained gummy; [a& + 57” (CH,Cl,): ‘H NMR: 65.96 (lH, br d, J = 2.8 Hz, HI), 4.56 (IH, br s, H-18), 2.06 (OAc), 1.39, 1.03, 0.92 (3 x Me). Oxidation of the acetonide with Jones’ reagent gave the 11-keto derivative, also a gum, ‘H NMR: 65.64, (IH, br s, H-l), 4.61 (19 br s, H-l$a), 4.55 (IH, br s, H18b), 2.96 (lH, d, J= 12.3 Hz, H-12), 2.04 (OAc), 1.42, 1.36 (An), 1.42, 1.29, 0.84 (3 x Me). ent-Beyer-15-en-12a-ol (41). Isolated as a gum [@Jn + I”, (Found m/z 288.2444. Calc. for C,,H,,O: 288.2453); ‘HNMR: 65.7 (lH, d, J=5.6 Hz, H-16), 5.54 (LH, d, J =5.6 Hz, H-15), 3.67(lH,m, 5 lines, separation 1.8 Hz, H12), 1.06, 0.87, 0.83, 0.70 (4x Me). The acetate had mp 114-l 16L(MeOH), [xl,, - 56” (C&Cl,); ‘H NMR: 65.81 (lH, d, j=5.7 Hz, H-16), 5.53 (lH, d, f=5.6 Hz, H-15), 4.84(lH, m, J= 1.9 Hz, H-12), 2.05 @AC), 0.98,0.87,0.82, 0.69 (4 x Me). Compound 41 (15 mg) in Me,CO was oxidized with Jones’ reagent, the ketone was obtained as a gum (II mg), [~l]n--341” (CH,Cl,); IR v,,, 17lOcm-I: ‘H NMR: 66.05 (IH, d, 5=5.5 Hz, H-16), 5.57 (lH, d, J =5.3 Hz, H-15), 1.08, 0.87, 0.83, 0.76 (4 x Me). ent-Beyer- 15-en-7-one (42). Needles, mp 152-l 54” (MeOH), [y.&, -12” (CH,CI,); (Found m/z 286.2290, &,H,,O requires: 286.2297). ‘H NMR: 65.57 (2H, d, J ~10.6 Hz, H-15, H-16), 1.07, 0.92, 0.86, 0.86 (4x Me). Borohydride reduction of 42 (10 mg) gave ent-beyer- t5en-7-01 (7mg), ‘HNMR:~5.69(lH,d,~=5.6Hz,H-l6)~ 5.56(1H, d, J-5.9 Hz, H-IS), 3.42 (IH, dd, J=ll.l, 5.1
et al.
Hz, H-7), 1.04,0.87,0.84,0.7.5 (4 x Me). The acetate (5 mg) had1HNMR:~5.74(lH,d,~=5.7Hz,H-16),5.47~lH,d, J=5.6Hz,H-15),4.75(lH.dd,J=l0.7,5.3 Hz,H-7),2.12 (OAc), 1.10, 0.97, 0.93, 0.8 (4 x Mel. ent-Beyer-15-en-19-nI (43). Oil, [a&+28” (CH,Cl,); ‘H NMR: 69.97 (lH,.s, H-19), 5.70(1H,d,J=5.6, H-16), 5.47 (lH, d, J-5.8 Hz, H-15), 1.01, 1.01, 0.62 (3xMe), borohydride reduction of 43 (100 mg) gave ent-beyer-15en-19-01 (100 mg), needles mp 116-l 18” (hexane). A soln of beyer-15-en-19-01 (500 mg) in CH,Cl, was oxidised with excess Collins’ reagent, yielding the aldehyde (200 mg) as a semi-crystalline gum. Acknowledgements-We thank the folowing people for the collection of plant material. Dr Caesar Catalan ~Universidad NacionaI de Tucuman, Argentina), Mr Don Nicholson, (Dept. of Forestry, Australia), Mr John Clarkson, (Dept. of Primary Industries, Australia), Dr Amantino Ramos de Freitas (Instituto de Pesquisas Technologicas do Estado de Sao Paulo, Brazil), Dr T. Zanoni (Jardim Botanic0 National, Republica Dominicana), Mr A. Owadally and Mr M. Dull00 (Forestry Service, Mauritius), Dr John de Freitas (Stichting Carambi, Netherlands Antilles), Dr Stephanie La Barre (C.N.R.S., New Caledonia), Dr G. Schmeda Hirschmann, (Universidad Naeional de Ascunscion, Paraguay), Dr John Francis (Dept. of Agriculture, Puerto Rico), Mr Ali Tbrahim (Botanic Gardens, Singapore), Mr L. Powrie (Lowveld Botanic Gardens, RSA), and Dr T. Mutler (National Herbarium, Zimbabwe). We thank Dr. M. Bokel (University of Hohenheim, Stuttgart) for NMR spectra, and Prof. G. Rucker (Bonn University for high resolution mass spectra. SMA is grateful to the CSIR for a maintenance grant.
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