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An approach to chiral η4-butadiene-Fe(CO)3 complexes via diastereoselective complexation of nonracemic 2-alkoxy-4-vinyl-2,5-dihydrofuran derivatives
TetrahcdmnLetiefx Vd. 35, NO. 26, pp. 45434546, 1994 ElsevierS&ace Ltd Printedin CheatBritain oo40-4039/94 $7.00+0.00
An Approach to Chiral q4-Butadiene_Fe(CO)3 Complexes via Diastereuse&tive Complexation of Nonracemic 2-A~ko~4viny~-~~ihydrofu~n
De~va~v~
Hans-GMther Schmalz*, Erik He&r, Jan W. Bats, and Gerd Diirner
Due to their interesting chemical and stereochemical prop&es, chixal q4- 1,3-butadiene-Fc(C!O)3 complexes of both cyclic’ and acyclic2 diem ligands offer as synthetic building blocks new strategiesfor the total synthesis of biologically active compounds3. If in the course of a synthesis, new, pcramncntchirality oonras~gcnetlttedd~undcatheinnuenceOf
~C~~~~.~~~
competitivenessof such synthesesdepends to a 1~
extenton the ~sibility
6f the startingcomplexes in
opticallyactivefomL The
techniques reportedin the litezaturefor the lmparation of nonracemicf14-Ft
3
Scheme 1 4543
en&4
4544
As chiral ligands, we decided to investigate 2-alltoxy-4~vinyl-2,5_dihydrofuran
derivatives of type 1.
These compounds possess a removable chirality center (acetal carbon) close to the diene unit. Furthermore, tbe orientation of the alkoxy (OR’) substituent is conformationally
restricted due to the presenfze of the five-
membered ring. Thus, ccxuplexation should more or less seketively 3, which @fter separation) should be, for instance, hy~~lc
finnish the U
products 2 or
to the optically active ahiehyde complexes of
type 4 (or 4~zf-4, respectively). The synthesis of the chiral diene ligand& was carried out accotding to Scheme 2. First, the epoxide 6 was prepared from (c)-L-arabinose employing
(5) in 78% overall yield using modified literature procedures7.
the method of Magnusson8,6
was transfotmed
By
to the aldehyde 7, which was then converted to
the dienes 8a and Sb. respectively, under standard Wittig conditions.
H
-s!25
H
5
6
7
&I (R=H)
86%
8b (R = CQEt)
99%
!&eme 2: a) BZIOH. HC& 0 OC-+ tt., 12 h; b) 2f-dimetboxypropane. p-TsOH, reflux. 2 h; c) p-TsCl, pyridim, r.t., 2 d; d) 1 N HCI, THF. ct. -+ SOOc, 12 h: e) NaOMe, MeOH, 0 Qc -a r.t., 12 h; r) 4.1 eq. LiBr. 4.1 eq. TMU. toluene,reflux, slowadditionof 6.90 min; g) Ph,P=CH,. THF. -90 *C + 0 “c, 3 h: h) Ph.+SHCO&
Complexation exe- and en&-
of these ligands (8) with Fe2(CO)9 (2.0 eq., 4 - 5 h reflux) furnished a mixture of the
diastereomers
9 and 10 in varying ratios dependent
on the solvent used (Table 1)9. The
highest yields and selectivities wete obtained in ether. The prevailing f-on e&-isomers
10 undertheseconditions can presumably
might lx formed as an intermedkte
Thus, an endo_172-complex of type 11
which in tom could dire&y pass into the obsetved major product 10.
8a(R-H) 8b (R = CO&f)
Table 1: Complexation
of the (stericaUy less favor&)
be rationalized in terms of a primary coordination
of the Fe(CO)x species to the oxygen of the benzyloxy Su~ti~entlO.
1 2 3 4
THF, 50 “c. 4 h;
18a (R = H) lob (R = CGEt)
of dienes &t/b with Fe#O)9
:
diene
solvent
yield (%)
8a 8s 8a 8b
Et20 n-heptane toluene Et20
77 85 75 90
9: 1osj 32 : 68 59: 41 43 : 57 25 : 75
separated products b, vieids (%) 9a: 24 9a: 48 ____ 9b: 20
lOa: 52 1Oa: 35 ___I lob: 59
a) ratiode&minediium theIH NMR spectra of thepurifieddiawreomermixtwq b) is&ted afterflashcbromatogmphy.
4545
Jll 2s 20 13
10 S
10 s 0 -5
0
-ia -1S -%I -23 -3a
-s -10
1: CD gpccti in h&OH : left 9s (-),
Figure
1Oa (----);
zighe 9b (-).
and
F&WC?
2:
and 1Db {----}
Structure
of
Sb
in the solid
siaIe’2
The mixtures of diastereomeric complexes (94lOa and 9bfiOb. nspcctivciy)
wue found to be easily
(Fipre
1) displayed a pseudo-
separable by flash chromatography. cnantiomorphic
The CD spectra of the pure complexes
behaviour for each pair of diastereomers. The telativc configuration of the ester comp~cxes
9b and 10b was (primarily) assigned by correlating the Cotton effects at about 400 nm with the data of and later confirmed by a sina;le crystal X-ray analysis of 9b (Figure 2)12. The configuration of 9a and IOa could then be assigned by comparison of thcii lH NMR spectra (270 MHz, CDCl$ with those of
Ortell.
9b and lab. In particular, the signal of the acetal hydrogen exhibited a characteristic pattern: In the case of the exe-isomers
9a aud 9b this signal appeared as a pseudo-singlet
at ca. 5.2 ppm, while for the cndo-
isomers IOa and lob it showed up as a doublet (3 = 2-3 Hz-) at about 5.5 ppm in both cases. In conclusion, we have elaborated a new entry to chii
butadiene-Fe(CO)3 complexes of type 2 and 3
of known absolute and relative cottfigutation in enantiomerically en&complexes transformations,
pure fm.
These canpuunds (espmidly the
3) are now accessible in sufficient quantities to allow ftmhcr investigations. e.g. the preparation of complexes
4 and ent-4, respectively.
Some synthetic
by aeetal hydrolysis,
ate
described in the accompanying paw@. Acknowledgement. Fends der Chemischen
This work was supported by the Deutsche
Forsehungsgemeinschaft
and the
Industrie. We also thank Prof_ Dr. G. Quinkert, Frankfint, for generous support.
~~~N~S
1.
a) Collman, J.P.; Hegedus, L.S.; Norton, J-R.; Finke, R-G. PrJncJpJes ad AppJkztions of Orgawtransitiort Metal Chcmisny, University Science Books, Mill Valley, 1987. p. 848, b) Pearson, A.J.; in Comprehensive OrgunometalJic Chetisrry; Wilkinson, G.; Stone. F.G.A.; Abel, E.W.; Eds.; Pergamon: Oxford, 1982, Vol. 8. Chap. 58, p. 939: c) Birch, A.J. et al.; Tetrahedron 1981,37 (Suppl. l), 289; d) Knalker, H.-J.; Sydett 1992,371.
4546
2.
3.
4.
5.
6. 7. 8. 9.
10.
11. 12.
13.
a) Grt?e. R. Synthesis 1989, 341, and references cited therein; b) Franck-Neumann, M.; in Organomerallics in Or#znic Synthesiq de Meijere, A.; tom Die&, H.; Eds.; Springer-Verlag, Berlin, 19%7,p. 247, and references cited the&n. For recent work see: a) Gigou, A.; Beaucourt, J.-P., Lellouche, J.-P.; G&e, R. Tetrahedron Len. 1991,32, 635; b) Fran&-Neumann, M., Colson, P.-J. Synlerr 1991. 891; c) Nunn. IC.; Morset, P.; Gr6e. R. ; Saalfia& R. W. J. Org. Chem. 1992.57, 3359; d) Tao, C.; Donaldson. W. A.; J. Org. Chem. 1993.58, 2134. a) Muaco, A.; Palumbo, R.; Paiatv, G. Incrg. Chim. Acta 1971.5. 157; b) Pinsani, P.: Lellouche, J.-P.; Beaucourt,J.-P.; GrCe, R. Tezruhedron Serf. 1990.31, 1137; c) Franck-Neumann, M.; Martina, D.; Heitz, M.P. J. Orgatwmet. Chem. 1986,301,61; d) Alcock, N.W.; Crout, D.H.G.; Henderson, CM.; Thomas, SE.; J. Chem. Sot., Chem. Commun. 1988,746, e) Howell, J.A.S.; Palin, M.G.; Jaouen, G.; Top, S.; El Hafa, H.; Cense, J.M.; Tetrahedron: Asymmetry 1993.4, L.err. 1241; f) Uemura, M.; Nishimura, H.; Yamada, S.; Nakamura, K.; Hayashi, Y.; Tenaltedron 1993,34, 6581. The dins enantiodective complexation of prochiral diene ligands was investigated but only low yields and selectivities were obtained : Birch, A.J.; Raverty, W-D.; Stephenson, G.R. Organometullics 1984.3, 1075. All new compounds were fully characterized by the usual spectroscopic methods and gave correct elemental analyses. a) Garegg. P. J. Acfu. Chem. Scwrd. 1960.14, 12; b) Pettersson, L.; Frejd, T.; Magnusson, G. J. Org. Chem. 1984.49, 4540. a) Sundin. A.; Ftejd, T.; Magnusson, G. J. Org. Chem. 1986.51, 3927; b) Magnusson, G. Chem. Ser. 1987,27, 571. Selected data for compounds 9a, 9b. lOa, and lob: 9a : Fp. 72-73 OC; [a] ho = + 286.0° (c = 0.9 in CHCl;): 9b : Fp. 82-85 ‘c; [a] p= + 276.4’ (c = ‘0.5 in MeGH); 1Oa : Fp. 69-70 Oc; [a] go= - 136.S” (c = 0.9 in Cl%&); lob : Fp. 69-70“C; [a] go=- 187.8’ (c = 1.0 in MeGH). A related syrrdirecting effect of oxy-substitnents adjacent to a %-system is observed for the Cr(CG3)complexation of I-tetralol-derivatives: a) Davies, S.G.; Goodfellow, CL. J. Organomer. Chem. 1988,340, 195; b) Schmalz, H.-G.; Millies, B.; Bats, J.W.; Dtirner. G. Angew. Chem. 1992, 104.640;Angew. Gem., ht. Ed. En@. 1992.3Z. 631; and references cited therein. Djedaini, F.; Gr&, D.; Martelli, J.; G&e, R.; Leroy, L.; Bolard, J.; Toupet, L. Tetrahedron Lert. 1989.30, 3781. X-ray crystal structure analysis of 98: Enraf-Nonius CAD4 diffractometer, Cttka radiation, quadrant: 2 < 28 < 60 O,octant: 60 c 28 < 120 “; empirical absorption conection based on yr-scans; structure de-on with direct methods (SHELXS 86); the positions of the non-H atoms were determined by difference syntheses, and the hydrogen atoms in calculated positions were not refined. C#-IlgFe(+, orthorhombic, space group P2lP2lP2l (no. 19), a = 8.030(3) A, b = 8.063(3) A, c = 59.314(11) A, V = 3840(4) A3. Z = 8 (two independent molecules), pcalc = 1.433 glcm3; 3476 independent reflections, of which 3208 with I > 0 were used, R = 0.107, Ro, = 0.067. The residual density was less than 0.68 JAM. The enantiomorphic structure gave R = 0.148 and R, = 0.126 and could thus be excluded. Further details of the crystal structure investigation may be obtained from the Fachinfotmationszentrum Rarlsruhe, Gesellschaft ftir wissenschaftlich-technische Information mbH, D-76344 Eggenstein-Lcopoldshafen, Germany on quoting the depnsitory number CSD-55g95. He&r, E.; Schmalz, H.-G.; Diimer, G. Tetrahedron Z&r., 1994,35(following paper in this issue).
(Received in Germany 29 March 1994, accepted 5 May 1994)
An Approach to Chiral q4-Butadiene_Fe(CO)3 Complexes via Diastereuse&tive Complexation of Nonracemic 2-A~ko~4viny~-~~ihydrofu~n
De~va~v~
Hans-GMther Schmalz*, Erik He&r, Jan W. Bats, and Gerd Diirner
Due to their interesting chemical and stereochemical prop&es, chixal q4- 1,3-butadiene-Fc(C!O)3 complexes of both cyclic’ and acyclic2 diem ligands offer as synthetic building blocks new strategiesfor the total synthesis of biologically active compounds3. If in the course of a synthesis, new, pcramncntchirality oonras~gcnetlttedd~undcatheinnuenceOf
~C~~~~.~~~
competitivenessof such synthesesdepends to a 1~
extenton the ~sibility
6f the startingcomplexes in
opticallyactivefomL The
techniques reportedin the litezaturefor the lmparation of nonracemicf14-Ft
3
Scheme 1 4543
en&4
4544
As chiral ligands, we decided to investigate 2-alltoxy-4~vinyl-2,5_dihydrofuran
derivatives of type 1.
These compounds possess a removable chirality center (acetal carbon) close to the diene unit. Furthermore, tbe orientation of the alkoxy (OR’) substituent is conformationally
restricted due to the presenfze of the five-
membered ring. Thus, ccxuplexation should more or less seketively 3, which @fter separation) should be, for instance, hy~~lc
finnish the U
products 2 or
to the optically active ahiehyde complexes of
type 4 (or 4~zf-4, respectively). The synthesis of the chiral diene ligand& was carried out accotding to Scheme 2. First, the epoxide 6 was prepared from (c)-L-arabinose employing
(5) in 78% overall yield using modified literature procedures7.
the method of Magnusson8,6
was transfotmed
By
to the aldehyde 7, which was then converted to
the dienes 8a and Sb. respectively, under standard Wittig conditions.
H
-s!25
H
5
6
7
&I (R=H)
86%
8b (R = CQEt)
99%
!&eme 2: a) BZIOH. HC& 0 OC-+ tt., 12 h; b) 2f-dimetboxypropane. p-TsOH, reflux. 2 h; c) p-TsCl, pyridim, r.t., 2 d; d) 1 N HCI, THF. ct. -+ SOOc, 12 h: e) NaOMe, MeOH, 0 Qc -a r.t., 12 h; r) 4.1 eq. LiBr. 4.1 eq. TMU. toluene,reflux, slowadditionof 6.90 min; g) Ph,P=CH,. THF. -90 *C + 0 “c, 3 h: h) Ph.+SHCO&
Complexation exe- and en&-
of these ligands (8) with Fe2(CO)9 (2.0 eq., 4 - 5 h reflux) furnished a mixture of the
diastereomers
9 and 10 in varying ratios dependent
on the solvent used (Table 1)9. The
highest yields and selectivities wete obtained in ether. The prevailing f-on e&-isomers
10 undertheseconditions can presumably
might lx formed as an intermedkte
Thus, an endo_172-complex of type 11
which in tom could dire&y pass into the obsetved major product 10.
8a(R-H) 8b (R = CO&f)
Table 1: Complexation
of the (stericaUy less favor&)
be rationalized in terms of a primary coordination
of the Fe(CO)x species to the oxygen of the benzyloxy Su~ti~entlO.
1 2 3 4
THF, 50 “c. 4 h;
18a (R = H) lob (R = CGEt)
of dienes &t/b with Fe#O)9
:
diene
solvent
yield (%)
8a 8s 8a 8b
Et20 n-heptane toluene Et20
77 85 75 90
9: 1osj 32 : 68 59: 41 43 : 57 25 : 75
separated products b, vieids (%) 9a: 24 9a: 48 ____ 9b: 20
lOa: 52 1Oa: 35 ___I lob: 59
a) ratiode&minediium theIH NMR spectra of thepurifieddiawreomermixtwq b) is&ted afterflashcbromatogmphy.
4545
Jll 2s 20 13
10 S
10 s 0 -5
0
-ia -1S -%I -23 -3a
-s -10
1: CD gpccti in h&OH : left 9s (-),
Figure
1Oa (----);
zighe 9b (-).
and
F&WC?
2:
and 1Db {----}
Structure
of
Sb
in the solid
siaIe’2
The mixtures of diastereomeric complexes (94lOa and 9bfiOb. nspcctivciy)
wue found to be easily
(Fipre
1) displayed a pseudo-
separable by flash chromatography. cnantiomorphic
The CD spectra of the pure complexes
behaviour for each pair of diastereomers. The telativc configuration of the ester comp~cxes
9b and 10b was (primarily) assigned by correlating the Cotton effects at about 400 nm with the data of and later confirmed by a sina;le crystal X-ray analysis of 9b (Figure 2)12. The configuration of 9a and IOa could then be assigned by comparison of thcii lH NMR spectra (270 MHz, CDCl$ with those of
Ortell.
9b and lab. In particular, the signal of the acetal hydrogen exhibited a characteristic pattern: In the case of the exe-isomers
9a aud 9b this signal appeared as a pseudo-singlet
at ca. 5.2 ppm, while for the cndo-
isomers IOa and lob it showed up as a doublet (3 = 2-3 Hz-) at about 5.5 ppm in both cases. In conclusion, we have elaborated a new entry to chii
butadiene-Fe(CO)3 complexes of type 2 and 3
of known absolute and relative cottfigutation in enantiomerically en&complexes transformations,
pure fm.
These canpuunds (espmidly the
3) are now accessible in sufficient quantities to allow ftmhcr investigations. e.g. the preparation of complexes
4 and ent-4, respectively.
Some synthetic
by aeetal hydrolysis,
ate
described in the accompanying paw@. Acknowledgement. Fends der Chemischen
This work was supported by the Deutsche
Forsehungsgemeinschaft
and the
Industrie. We also thank Prof_ Dr. G. Quinkert, Frankfint, for generous support.
~~~N~S
1.
a) Collman, J.P.; Hegedus, L.S.; Norton, J-R.; Finke, R-G. PrJncJpJes ad AppJkztions of Orgawtransitiort Metal Chcmisny, University Science Books, Mill Valley, 1987. p. 848, b) Pearson, A.J.; in Comprehensive OrgunometalJic Chetisrry; Wilkinson, G.; Stone. F.G.A.; Abel, E.W.; Eds.; Pergamon: Oxford, 1982, Vol. 8. Chap. 58, p. 939: c) Birch, A.J. et al.; Tetrahedron 1981,37 (Suppl. l), 289; d) Knalker, H.-J.; Sydett 1992,371.
4546
2.
3.
4.
5.
6. 7. 8. 9.
10.
11. 12.
13.
a) Grt?e. R. Synthesis 1989, 341, and references cited therein; b) Franck-Neumann, M.; in Organomerallics in Or#znic Synthesiq de Meijere, A.; tom Die&, H.; Eds.; Springer-Verlag, Berlin, 19%7,p. 247, and references cited the&n. For recent work see: a) Gigou, A.; Beaucourt, J.-P., Lellouche, J.-P.; G&e, R. Tetrahedron Len. 1991,32, 635; b) Fran&-Neumann, M., Colson, P.-J. Synlerr 1991. 891; c) Nunn. IC.; Morset, P.; Gr6e. R. ; Saalfia& R. W. J. Org. Chem. 1992.57, 3359; d) Tao, C.; Donaldson. W. A.; J. Org. Chem. 1993.58, 2134. a) Muaco, A.; Palumbo, R.; Paiatv, G. Incrg. Chim. Acta 1971.5. 157; b) Pinsani, P.: Lellouche, J.-P.; Beaucourt,J.-P.; GrCe, R. Tezruhedron Serf. 1990.31, 1137; c) Franck-Neumann, M.; Martina, D.; Heitz, M.P. J. Orgatwmet. Chem. 1986,301,61; d) Alcock, N.W.; Crout, D.H.G.; Henderson, CM.; Thomas, SE.; J. Chem. Sot., Chem. Commun. 1988,746, e) Howell, J.A.S.; Palin, M.G.; Jaouen, G.; Top, S.; El Hafa, H.; Cense, J.M.; Tetrahedron: Asymmetry 1993.4, L.err. 1241; f) Uemura, M.; Nishimura, H.; Yamada, S.; Nakamura, K.; Hayashi, Y.; Tenaltedron 1993,34, 6581. The dins enantiodective complexation of prochiral diene ligands was investigated but only low yields and selectivities were obtained : Birch, A.J.; Raverty, W-D.; Stephenson, G.R. Organometullics 1984.3, 1075. All new compounds were fully characterized by the usual spectroscopic methods and gave correct elemental analyses. a) Garegg. P. J. Acfu. Chem. Scwrd. 1960.14, 12; b) Pettersson, L.; Frejd, T.; Magnusson, G. J. Org. Chem. 1984.49, 4540. a) Sundin. A.; Ftejd, T.; Magnusson, G. J. Org. Chem. 1986.51, 3927; b) Magnusson, G. Chem. Ser. 1987,27, 571. Selected data for compounds 9a, 9b. lOa, and lob: 9a : Fp. 72-73 OC; [a] ho = + 286.0° (c = 0.9 in CHCl;): 9b : Fp. 82-85 ‘c; [a] p= + 276.4’ (c = ‘0.5 in MeGH); 1Oa : Fp. 69-70 Oc; [a] go= - 136.S” (c = 0.9 in Cl%&); lob : Fp. 69-70“C; [a] go=- 187.8’ (c = 1.0 in MeGH). A related syrrdirecting effect of oxy-substitnents adjacent to a %-system is observed for the Cr(CG3)complexation of I-tetralol-derivatives: a) Davies, S.G.; Goodfellow, CL. J. Organomer. Chem. 1988,340, 195; b) Schmalz, H.-G.; Millies, B.; Bats, J.W.; Dtirner. G. Angew. Chem. 1992, 104.640;Angew. Gem., ht. Ed. En@. 1992.3Z. 631; and references cited therein. Djedaini, F.; Gr&, D.; Martelli, J.; G&e, R.; Leroy, L.; Bolard, J.; Toupet, L. Tetrahedron Lert. 1989.30, 3781. X-ray crystal structure analysis of 98: Enraf-Nonius CAD4 diffractometer, Cttka radiation, quadrant: 2 < 28 < 60 O,octant: 60 c 28 < 120 “; empirical absorption conection based on yr-scans; structure de-on with direct methods (SHELXS 86); the positions of the non-H atoms were determined by difference syntheses, and the hydrogen atoms in calculated positions were not refined. C#-IlgFe(+, orthorhombic, space group P2lP2lP2l (no. 19), a = 8.030(3) A, b = 8.063(3) A, c = 59.314(11) A, V = 3840(4) A3. Z = 8 (two independent molecules), pcalc = 1.433 glcm3; 3476 independent reflections, of which 3208 with I > 0 were used, R = 0.107, Ro, = 0.067. The residual density was less than 0.68 JAM. The enantiomorphic structure gave R = 0.148 and R, = 0.126 and could thus be excluded. Further details of the crystal structure investigation may be obtained from the Fachinfotmationszentrum Rarlsruhe, Gesellschaft ftir wissenschaftlich-technische Information mbH, D-76344 Eggenstein-Lcopoldshafen, Germany on quoting the depnsitory number CSD-55g95. He&r, E.; Schmalz, H.-G.; Diimer, G. Tetrahedron Z&r., 1994,35(following paper in this issue).
(Received in Germany 29 March 1994, accepted 5 May 1994)