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Dimethyldioxirane epoxidation of 6,6-disubstituted fulvenes.
Teaahcdron Letters. Vo1.32,No.46. pp 6697-6700, 1991
ocklo-4039191 $3.00 + .oo
Printed in Chat Britain
Pergamon Press plc
Dimethyldioxirane
Epoxidation
6,6-Disubstituted
of
Fulvenes.
Waldemar Adam*, Lazaros P. Hadjiampogloula, Anja Meffertlb Instituteof OrganicChemistry, Universityof Wilrzburg. AmHubland_D-&‘@IWtiurg, ‘&many.
Key Words : Dimethyldioxirane,
Epxidartin.
Pentaju.iwnc, Rcgiosekctvity,
Synrhtsis.
Abstract : Tk en&cyclichis-q&&s o/mrio~~pcn~u.lcncs were readily prepared by epoxi&tion with excess dimcthyl&xiranc: sraichi~mem’c cpoaidation yicldcd mixtures of tk bis-qwxides and thelabile nwnoepidcs, but 110c.wcyclic eptis wrc obserwd
Recently, it has been demonstrated
that the efficient but yet mild oxygen transfer agent
dimethyldioxirane2 is the reagent of choice for the epoxidation3 of electron-rich
as well as electron-poor
alkenes. For the latter substrates, as expected for this generally considered electrophilic oxidant,4 more strenuous conditions, e.g. higher temperatures, longer times and large excess of dioxirane, must be employed for complete conversion. Nevertheless, so far little is known5 about the sclcctivity in the oxygen transfer by dimethyldioxirant towards substrates with diverse double bonds. Subtrates of interest for this purpose are 6,6disubstituted pentafulvenes. which contain three cross-conjugated double bonds. i.e. two disubstituted endocyclic and the one exocyclic tetrasubstituted double bonds. Although generally tetrasubstituted double bonds react 6 faster towards elecbophilic oxidants than disubstituted ones, pcntafulvcnes are easily polarized7 in view of the significant contribution of tk charge-separated mesomeric form 1’ @q.l),
0
/\
R--I R
WG2,
R’
+
Fe
1’
a happenstance
CH$X'C&
(Es.1)
,
O
R2
R1
1
2
3
4
which controls their reactivity .Thus, in analogy to the addition of carbenes,*
for
pentafulvenes an elecwphilic oxidant would be expected to epoxidize the et&cyclic, a nucleophilic oxidant the exocyclic double bond, irrespective of the degree of substitution. Indeed, Weitz-Scheffer epoxidation9 (H2C+/base) of pcntafulvenes afforded the exocyclic epoxides. but the endccyclic mono6697
6698
epoxides were hitherto not observed by direct epnxidation. The endocyclic bis-epoxidcs prepared through the photochemical oxidation of 1,2,3,4-teuaphenyl-substituted
have been
pentafulvenesl*
and
subsequent thermal rearrangement of the initially formed endoperoxides. The analogous reaction with 66
dimethylpentafulvene t1 led to a complex mixture of products. As the results in Eq. 1 and Table 1 display, dimethyldioxirane (as acetone solution) reacts with various 6,bdisubstituted pentafulvenes 1 exclusively at the endocyclic double bonds even with a large excess of oxidant The simple and convenient epoxidation procedure consists of rapid addition of the dioxiranc (1.0-3.1 equiv.) to a cooled (-100 to ca. 20 Oc). stirred solution of the pentafulvenes la-d (0.741.00 mmol) in absolute CH$l,
(5 ml) under a N, atrnosphert. The stirring was continued until complete
consumption of the pentafulvene (monitored by t1.c.) and evaporation (00 to ca 20 %! at 15 Tar) of the solvent yielded a mixture of 2 and 3 in excellent yields (cf. Table 1). Table 1: Epoxidationaof Pentafulvenes Fulvene
Reaction Conditions Temp. Time Rati
Substituents R’
Me
la
lb
Me
lc
Me
ld
Ph
1 by Dimethyidioxirane
R2
(min)
ec)
Yieldb (“/o)
Product 2 Distri;ion
4
1 :DMD
-10
180
1 : 1.14
>95Q
70
30
0
0
240
1 : 2.5
91
0
100
0
-10
180
1 :1
>95 0
0
15
85
0
180
1 : 2.5
85
0
100
0
-10
180
1 :l
>95 r)
83
17
0
0
240
1 :3.1
a9
0
100
0
-10
120
1 :l
>95 O)
81
19
0
5
1 : 2.2
Cal00
0
loo
0
Me
A Ph
Ph 20
‘lnCH&~/Ct+QX&
(DMD).
u&rN2atmo@we.
b Wd of Lsokled pure m.
‘) For weld
data consult Ref. 12.6) 95% amversion. e, 85 % cwversion.~ 81% conversion.0) 75% conversion.
Epoxidation of the pentafulvenes 1 with stoichiometric amounts of dimethyldioxirane yielded mixtures of the monocpoxidc 2 (major product) and the biscpoxide 3 (minor product) . For example, pentatklvenc lc affoded at -78 Oc, afforded the two possible mono-epoxides 2c and 2c ’ in a 1:l ratio (80% yield). besides the bisepoxide
k
(29% yield). On standing at room temperature in the NMR tube,
the mixture of mono-epoxides 2c and 2c ’ decomposed into a mixture of the isomeric 3-cyclopenten-lones 4c and 4c’ monoepoxide
(Eq. 2), which were purified by column
chromatography and characterizedt2. The
2 dwas mart stable than the unsymmeuically substituted 2 c / 2 c ‘, but all were sufficiently
6699
F=q.2)
2 2c, 4c
4 : R’= Me, I? = Ph
2c’,4c’: R’= Ph, R2 = Me persistent for spectral characterization 12. In contrast, the mono-epoxides 2a,b
were too labile and
rearrauged to the cyclopenentenone derivatives 4 during the work-up even at 0 Oc. When an excess of dimethyldioxirane (2.2-3.1 equiv.) was employed, the biscpoxides 3 (Table 1) wen obtained essentially quantitatively in pure form (*H NMR). In the case of Id, by employing even larger amounts of dioxirane, longer reaction time (-48 h), and higher temperatures (ca. 20 oc), fi0 epoxidation occurn%l at the exocyclic double bond. Altbough the spectral data of the bis-epoxides 3 speak for a single isomer, it was not possible to discriminate between syn or arJi addition of the second oxygen atom since NOE experiments on the epoxide 3c for example wem ~ncIusive. In summary, we have shown again the great utility of dimethyldioxirane in serving as a convenint and an efficient oxygen transfer agent for the epoxidation of 6,bdisubstituted pentafulvenes. By employing an excess of dioxiranc the endocyclic biscpoxidcs were obtained in quantitative yields. The exocyclic double bond is not epoxidixed, which speaks for the el~~ph~ nature of ~e~yl~o~e as oxidant Acknowledgements: The technical assistence of Mr. J. Bialas, the generous gift of potassium monoperoxy sulfate from Degussa AG (Hanau, Germany) and Peroxid-Chemie GmbH (Milnchen, Gerry), and the financial support from the Deutsche F~hungsgemeinsch~t (SFB 347 “Selektive Reaktionen Metall-ahtivicrter Molekiile”) and the Fonds der Chemischen Industrit are gratefully appreciated. REFERENCES 1.
2. 3. 4. 5. 6. 7. 8. 9.
a Recipient of the 1991 INTBROX Junior Award. b. Undergraduate Research Participant, University of Wilrzburg, Spring 199 1. Adam, W. ; Hadjiarapoglou, L. ; Smerz, A. Chcm. Ber. 1991,124, 227. Adam, W. ; Curci. R. ; H~ji~glou, L. ; Mello, R. in Organic Peroxides, Ando, W. Ed., Wiley-Interscience, in press. a. Baumstark, A. L. ; Vasquez, P. C. J.Org. Chem. 1988,53, 3437. b. MURSY,R. W. ; Wang, D. L. J. Chem. Sot. Perkin It 1990, 349. Nicolaou, K. C. ; Prasad, C!, V C. ; Ogiltie, W. W. 1. Am. &hem. Sot. 1990,112,4988. March, J. Advanced Organic Chemistry, Wiley-Interscience, New York 1985,3rd edition, p. 735. Neuen~hw~~r, M. Fulvenes, In Tfrr Chemistry of ~5~~e-~~~d Fade Croups, Supplment A, Patai, S. Ed, Wiley, New York 1989, Chapter 16, pp. 1131-1268. MOSS, R. A. ; Young, C. M. ; Perez, L. A. ; Krogh-Jespersen, K. J. Am. Chem. SM. 198 1, 103, 2413. Alder, K. ; Flock. E H, ; Lessertick, H. Chem. Ber. 1957, PO, 1709.
6700
I. -J. CR. H&d. Seances Akad. Sci 1970, 271c, 461.
10.
LeRoux,
J. -P. ; Basseleir.
11.
Hawk
N. ; Suzuki, S. ; Uda, M. ; Ucno, H. J. Am. Chem.
12.
tc
: ‘I3 NMR CXJO MHz, CIXl$:
6.14-6.17
k’
1972,94,
1777. (m, III),
4.28-4.30
(m, 2H), 7.09-7.41 (m, 5H).-
: ‘H NMR (2OO MHz, CIXl,):
7.09-7.41{m, 2d
Sot.
6 = 2.40 (s, 3H), 3.85-3.91 (m,lH),
6 = 2,ll
(s, 3H), 3.85-3.91 (m, 2H), 6.48-6.55(m,
2H),
5H).-
: ‘H NMR (200 MHz, CDCl$:
lOW.- 13c N~(63~,
6 = 4, 26-4.27 (m, 2H), 6.42-6.44 (m. 2H), 7.34-7.44 (m,
CDCl$:6=
55.9 (df, 60.7 (d), 127.9 (d). 128.0 (d), 128.1 (d),
129.8 (d), 130.4 (d), 130.6 (d), 134.0 (d), 137.4 (d), 140.4 (s), 140.5 (s), 142.3 (s).3a : IR (CCl,J : v = 3020 cm-‘, 1450, 1375, 1000, 870.6,
6H), 3.56 (t, Jt=2.13 Hz, J2=2.36 Hz, W),
W3)
: 6 = 20.7 (9). 51.0 (d), 59.6 (d),
3 b : IR (CC14) : v
= 3000
cm-l,
3.86 {t, J= 2.13 Hz, 2H).-
13C NMR (63 MHz,
128.5 (s), 140.1 (s).-
1370, 990, 870.- ‘H NMR (250 MHz, CD&):
4H), I.55 (s, 3H1, 1.75-1.80 (m, lH), W,
‘H NMR (250 MHZ, C!DC13): 6 = 1.84
6 = 0.63-0.71
(m,
3.56 (quint., J= 1.52 Hz, IH), 3.74 (quint., J= 1.52 Hz,
3.88 (dq, J,= 8.03 Hz, J,= 1.51 Hz, 2H).- 13C NMR (63 MHz, CDCl,) : 6 = 2.8 (t), 2.9(t),
11.8 (dh 12.6 (q), 49.0 (dh49.5 (d), 57.3 (d), 57.6 (d), 126.6 (s), 142.0 (s).3C : IR KXQ
: v = 3090 cm-1,1210,
3Hh 3.26-3.28
(m, lH), 3.63-3.68
1010, 890, 720.-.*H NMR (250 MHz, CIX!I,): 6 = 2.18 (s,
(m, IH),
J,= 2.84 Hz, Jz= 1.22 Hz, lH), 7.18-7.36 52.260,
53.4(d), 60.6(d), 61.5(d),
3d : IR (CCL) : v = 3090 cm-l,
3.83 (dd, J,= 2.26 Hz, J,= 1.06 Hz, lH), 3.93 (dd, (m, 5H).-13C NMR (63 MHz, CDCl$:
6 = 20.5 (q),
128.1(d), 128.3 (d), 128.8 (d), 131.5 (s), 141.0 (s). 143.8(s).-
1290, 880, 720.-‘H FWR (250 MHZ, CDCl,): 6 = 3.40 (t, I= 1.95
HZ, 2H), 4.04 (t, J= 1.95 Hz, 2H),
7.32-7.37 (m, lOH).- l%Z NMR (63 MHz, CD&)
: 6 = 54.5
@I, 62.5 @I, 129.0 (d). 130.5 (d), 134.1 (s), 140.5 (s), 148.3 (s).4c : ‘H NMR (250 MHz, CDCl$:
6 = 2.45 (s, 3H), 2.84 (t, J = 2.21 Hz, 2H), 5.97 (dt, J1=
7.13 Hz, Jz= 0.82 Hz, lH), 6.14 (d, J= 7.13Hz, lH), 7.09-7.41 (m, SE%).- 13C NMR (63 MHZ, m,):
6 =19.5 (9), 43.5 (t), 127.8 (d), 128.0 (d). 128.1 (d), 128.3 (d), 133.7 (s), 134.2 (d),
142.8 (s), 144.8 (s), 206. 4(s).4c’ : ‘H NMR (250 MHz, CIXl,}: 7.03
6 = 2.10 (s, 3H), 2.77 (t, J = 2.23 Hz, 2H), 6.64 (dt, Jl =
Hz, J2 = 2.06 Hz, lH), 6.89 (dt, J, = 7.14 Hz, J, = 2.15 Hz, IH). 7.09-7.41
(m, 5H).-
13c NMR (63 MHz, CDC13) : 6 = 23.8 (q), 43.3 (t), 127.7 (d), 127.8 (d), 128.3 (d), 129.6 (d), 133.3 (s),
133.4 (d). 140.7 (s), 142.9 (s), 202.3 (s).-
(Received
in Germany
18 August 1991)
ocklo-4039191 $3.00 + .oo
Printed in Chat Britain
Pergamon Press plc
Dimethyldioxirane
Epoxidation
6,6-Disubstituted
of
Fulvenes.
Waldemar Adam*, Lazaros P. Hadjiampogloula, Anja Meffertlb Instituteof OrganicChemistry, Universityof Wilrzburg. AmHubland_D-&‘@IWtiurg, ‘&many.
Key Words : Dimethyldioxirane,
Epxidartin.
Pentaju.iwnc, Rcgiosekctvity,
Synrhtsis.
Abstract : Tk en&cyclichis-q&&s o/mrio~~pcn~u.lcncs were readily prepared by epoxi&tion with excess dimcthyl&xiranc: sraichi~mem’c cpoaidation yicldcd mixtures of tk bis-qwxides and thelabile nwnoepidcs, but 110c.wcyclic eptis wrc obserwd
Recently, it has been demonstrated
that the efficient but yet mild oxygen transfer agent
dimethyldioxirane2 is the reagent of choice for the epoxidation3 of electron-rich
as well as electron-poor
alkenes. For the latter substrates, as expected for this generally considered electrophilic oxidant,4 more strenuous conditions, e.g. higher temperatures, longer times and large excess of dioxirane, must be employed for complete conversion. Nevertheless, so far little is known5 about the sclcctivity in the oxygen transfer by dimethyldioxirant towards substrates with diverse double bonds. Subtrates of interest for this purpose are 6,6disubstituted pentafulvenes. which contain three cross-conjugated double bonds. i.e. two disubstituted endocyclic and the one exocyclic tetrasubstituted double bonds. Although generally tetrasubstituted double bonds react 6 faster towards elecbophilic oxidants than disubstituted ones, pcntafulvcnes are easily polarized7 in view of the significant contribution of tk charge-separated mesomeric form 1’ @q.l),
0
/\
R--I R
WG2,
R’
+
Fe
1’
a happenstance
CH$X'C&
(Es.1)
,
O
R2
R1
1
2
3
4
which controls their reactivity .Thus, in analogy to the addition of carbenes,*
for
pentafulvenes an elecwphilic oxidant would be expected to epoxidize the et&cyclic, a nucleophilic oxidant the exocyclic double bond, irrespective of the degree of substitution. Indeed, Weitz-Scheffer epoxidation9 (H2C+/base) of pcntafulvenes afforded the exocyclic epoxides. but the endccyclic mono6697
6698
epoxides were hitherto not observed by direct epnxidation. The endocyclic bis-epoxidcs prepared through the photochemical oxidation of 1,2,3,4-teuaphenyl-substituted
have been
pentafulvenesl*
and
subsequent thermal rearrangement of the initially formed endoperoxides. The analogous reaction with 66
dimethylpentafulvene t1 led to a complex mixture of products. As the results in Eq. 1 and Table 1 display, dimethyldioxirane (as acetone solution) reacts with various 6,bdisubstituted pentafulvenes 1 exclusively at the endocyclic double bonds even with a large excess of oxidant The simple and convenient epoxidation procedure consists of rapid addition of the dioxiranc (1.0-3.1 equiv.) to a cooled (-100 to ca. 20 Oc). stirred solution of the pentafulvenes la-d (0.741.00 mmol) in absolute CH$l,
(5 ml) under a N, atrnosphert. The stirring was continued until complete
consumption of the pentafulvene (monitored by t1.c.) and evaporation (00 to ca 20 %! at 15 Tar) of the solvent yielded a mixture of 2 and 3 in excellent yields (cf. Table 1). Table 1: Epoxidationaof Pentafulvenes Fulvene
Reaction Conditions Temp. Time Rati
Substituents R’
Me
la
lb
Me
lc
Me
ld
Ph
1 by Dimethyidioxirane
R2
(min)
ec)
Yieldb (“/o)
Product 2 Distri;ion
4
1 :DMD
-10
180
1 : 1.14
>95Q
70
30
0
0
240
1 : 2.5
91
0
100
0
-10
180
1 :1
>95 0
0
15
85
0
180
1 : 2.5
85
0
100
0
-10
180
1 :l
>95 r)
83
17
0
0
240
1 :3.1
a9
0
100
0
-10
120
1 :l
>95 O)
81
19
0
5
1 : 2.2
Cal00
0
loo
0
Me
A Ph
Ph 20
‘lnCH&~/Ct+QX&
(DMD).
u&rN2atmo@we.
b Wd of Lsokled pure m.
‘) For weld
data consult Ref. 12.6) 95% amversion. e, 85 % cwversion.~ 81% conversion.0) 75% conversion.
Epoxidation of the pentafulvenes 1 with stoichiometric amounts of dimethyldioxirane yielded mixtures of the monocpoxidc 2 (major product) and the biscpoxide 3 (minor product) . For example, pentatklvenc lc affoded at -78 Oc, afforded the two possible mono-epoxides 2c and 2c ’ in a 1:l ratio (80% yield). besides the bisepoxide
k
(29% yield). On standing at room temperature in the NMR tube,
the mixture of mono-epoxides 2c and 2c ’ decomposed into a mixture of the isomeric 3-cyclopenten-lones 4c and 4c’ monoepoxide
(Eq. 2), which were purified by column
chromatography and characterizedt2. The
2 dwas mart stable than the unsymmeuically substituted 2 c / 2 c ‘, but all were sufficiently
6699
F=q.2)
2 2c, 4c
4 : R’= Me, I? = Ph
2c’,4c’: R’= Ph, R2 = Me persistent for spectral characterization 12. In contrast, the mono-epoxides 2a,b
were too labile and
rearrauged to the cyclopenentenone derivatives 4 during the work-up even at 0 Oc. When an excess of dimethyldioxirane (2.2-3.1 equiv.) was employed, the biscpoxides 3 (Table 1) wen obtained essentially quantitatively in pure form (*H NMR). In the case of Id, by employing even larger amounts of dioxirane, longer reaction time (-48 h), and higher temperatures (ca. 20 oc), fi0 epoxidation occurn%l at the exocyclic double bond. Altbough the spectral data of the bis-epoxides 3 speak for a single isomer, it was not possible to discriminate between syn or arJi addition of the second oxygen atom since NOE experiments on the epoxide 3c for example wem ~ncIusive. In summary, we have shown again the great utility of dimethyldioxirane in serving as a convenint and an efficient oxygen transfer agent for the epoxidation of 6,bdisubstituted pentafulvenes. By employing an excess of dioxiranc the endocyclic biscpoxidcs were obtained in quantitative yields. The exocyclic double bond is not epoxidixed, which speaks for the el~~ph~ nature of ~e~yl~o~e as oxidant Acknowledgements: The technical assistence of Mr. J. Bialas, the generous gift of potassium monoperoxy sulfate from Degussa AG (Hanau, Germany) and Peroxid-Chemie GmbH (Milnchen, Gerry), and the financial support from the Deutsche F~hungsgemeinsch~t (SFB 347 “Selektive Reaktionen Metall-ahtivicrter Molekiile”) and the Fonds der Chemischen Industrit are gratefully appreciated. REFERENCES 1.
2. 3. 4. 5. 6. 7. 8. 9.
a Recipient of the 1991 INTBROX Junior Award. b. Undergraduate Research Participant, University of Wilrzburg, Spring 199 1. Adam, W. ; Hadjiarapoglou, L. ; Smerz, A. Chcm. Ber. 1991,124, 227. Adam, W. ; Curci. R. ; H~ji~glou, L. ; Mello, R. in Organic Peroxides, Ando, W. Ed., Wiley-Interscience, in press. a. Baumstark, A. L. ; Vasquez, P. C. J.Org. Chem. 1988,53, 3437. b. MURSY,R. W. ; Wang, D. L. J. Chem. Sot. Perkin It 1990, 349. Nicolaou, K. C. ; Prasad, C!, V C. ; Ogiltie, W. W. 1. Am. &hem. Sot. 1990,112,4988. March, J. Advanced Organic Chemistry, Wiley-Interscience, New York 1985,3rd edition, p. 735. Neuen~hw~~r, M. Fulvenes, In Tfrr Chemistry of ~5~~e-~~~d Fade Croups, Supplment A, Patai, S. Ed, Wiley, New York 1989, Chapter 16, pp. 1131-1268. MOSS, R. A. ; Young, C. M. ; Perez, L. A. ; Krogh-Jespersen, K. J. Am. Chem. SM. 198 1, 103, 2413. Alder, K. ; Flock. E H, ; Lessertick, H. Chem. Ber. 1957, PO, 1709.
6700
I. -J. CR. H&d. Seances Akad. Sci 1970, 271c, 461.
10.
LeRoux,
J. -P. ; Basseleir.
11.
Hawk
N. ; Suzuki, S. ; Uda, M. ; Ucno, H. J. Am. Chem.
12.
tc
: ‘I3 NMR CXJO MHz, CIXl$:
6.14-6.17
k’
1972,94,
1777. (m, III),
4.28-4.30
(m, 2H), 7.09-7.41 (m, 5H).-
: ‘H NMR (2OO MHz, CIXl,):
7.09-7.41{m, 2d
Sot.
6 = 2.40 (s, 3H), 3.85-3.91 (m,lH),
6 = 2,ll
(s, 3H), 3.85-3.91 (m, 2H), 6.48-6.55(m,
2H),
5H).-
: ‘H NMR (200 MHz, CDCl$:
lOW.- 13c N~(63~,
6 = 4, 26-4.27 (m, 2H), 6.42-6.44 (m. 2H), 7.34-7.44 (m,
CDCl$:6=
55.9 (df, 60.7 (d), 127.9 (d). 128.0 (d), 128.1 (d),
129.8 (d), 130.4 (d), 130.6 (d), 134.0 (d), 137.4 (d), 140.4 (s), 140.5 (s), 142.3 (s).3a : IR (CCl,J : v = 3020 cm-‘, 1450, 1375, 1000, 870.6,
6H), 3.56 (t, Jt=2.13 Hz, J2=2.36 Hz, W),
W3)
: 6 = 20.7 (9). 51.0 (d), 59.6 (d),
3 b : IR (CC14) : v
= 3000
cm-l,
3.86 {t, J= 2.13 Hz, 2H).-
13C NMR (63 MHz,
128.5 (s), 140.1 (s).-
1370, 990, 870.- ‘H NMR (250 MHz, CD&):
4H), I.55 (s, 3H1, 1.75-1.80 (m, lH), W,
‘H NMR (250 MHZ, C!DC13): 6 = 1.84
6 = 0.63-0.71
(m,
3.56 (quint., J= 1.52 Hz, IH), 3.74 (quint., J= 1.52 Hz,
3.88 (dq, J,= 8.03 Hz, J,= 1.51 Hz, 2H).- 13C NMR (63 MHz, CDCl,) : 6 = 2.8 (t), 2.9(t),
11.8 (dh 12.6 (q), 49.0 (dh49.5 (d), 57.3 (d), 57.6 (d), 126.6 (s), 142.0 (s).3C : IR KXQ
: v = 3090 cm-1,1210,
3Hh 3.26-3.28
(m, lH), 3.63-3.68
1010, 890, 720.-.*H NMR (250 MHz, CIX!I,): 6 = 2.18 (s,
(m, IH),
J,= 2.84 Hz, Jz= 1.22 Hz, lH), 7.18-7.36 52.260,
53.4(d), 60.6(d), 61.5(d),
3d : IR (CCL) : v = 3090 cm-l,
3.83 (dd, J,= 2.26 Hz, J,= 1.06 Hz, lH), 3.93 (dd, (m, 5H).-13C NMR (63 MHz, CDCl$:
6 = 20.5 (q),
128.1(d), 128.3 (d), 128.8 (d), 131.5 (s), 141.0 (s). 143.8(s).-
1290, 880, 720.-‘H FWR (250 MHZ, CDCl,): 6 = 3.40 (t, I= 1.95
HZ, 2H), 4.04 (t, J= 1.95 Hz, 2H),
7.32-7.37 (m, lOH).- l%Z NMR (63 MHz, CD&)
: 6 = 54.5
@I, 62.5 @I, 129.0 (d). 130.5 (d), 134.1 (s), 140.5 (s), 148.3 (s).4c : ‘H NMR (250 MHz, CDCl$:
6 = 2.45 (s, 3H), 2.84 (t, J = 2.21 Hz, 2H), 5.97 (dt, J1=
7.13 Hz, Jz= 0.82 Hz, lH), 6.14 (d, J= 7.13Hz, lH), 7.09-7.41 (m, SE%).- 13C NMR (63 MHZ, m,):
6 =19.5 (9), 43.5 (t), 127.8 (d), 128.0 (d). 128.1 (d), 128.3 (d), 133.7 (s), 134.2 (d),
142.8 (s), 144.8 (s), 206. 4(s).4c’ : ‘H NMR (250 MHz, CIXl,}: 7.03
6 = 2.10 (s, 3H), 2.77 (t, J = 2.23 Hz, 2H), 6.64 (dt, Jl =
Hz, J2 = 2.06 Hz, lH), 6.89 (dt, J, = 7.14 Hz, J, = 2.15 Hz, IH). 7.09-7.41
(m, 5H).-
13c NMR (63 MHz, CDC13) : 6 = 23.8 (q), 43.3 (t), 127.7 (d), 127.8 (d), 128.3 (d), 129.6 (d), 133.3 (s),
133.4 (d). 140.7 (s), 142.9 (s), 202.3 (s).-
(Received
in Germany
18 August 1991)