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DOI: 10.1055/s-2003-39300
The Head-to-Head Reductive Coupling of Homoallylic Alcohols Promoted by Titanium(II)-Olefin Complexes
Publication History
Publication Date:
20 May 2003 (online)
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Abstract
Reaction of homoallylic alcohols 1a-e with i-PrMgBr in the presence of Ti(i-PrO)4 leads to the unbranched saturated diols 2a-e as the main products in moderate to good yields. The head-to-head regioselectivity in reductive coupling of 4-penten-1-ol and 5-hexen-2-ol was also observed. Coupling of 2-methyl-5-hexen-2-ol, as well as unsaturated alcohols in which vinyl and hydroxyl groups are more distant from one another, proceeded with head-to-tail or tail-to-tail regioselectivity. It is supposed, that the unusual head-to-head regioselectivity in reductive coupling of homoallylic alcohols 1a-e is due to the formation of the key titanacyclopentane intermediates F and G having two fused oxatitanacyclopentane rings.
Key words
titanium alkoxides - Grignard reagents - homoallylic alcohols - reductive coupling
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1a
Kulinkovich OG.Sviridov SV.Vasilevskii DA.Pritytskaya TS. Zh. Org. Khim. 1989, 25: 2244 -
1b
Kulinkovich OG.Sviridov SV.Vasilevskii DA. Synthesis 1991, 234 -
2a
Kulinkovich OG.Savchenko AI.Sviridov SV.Vasilevskii DA. Mendeleev Commun. 1993, 230 -
2b
Epstein OL.Savchenko AI.Kulinkovich OG. Tetrahedron Lett. 1999, 40: 5935 -
3a
Kulinkovich OG.Sviridov SV.Vasilevskii DA.Savchenko AI. Zh. Org. Khim. 1991, 27: 294 -
3b
Kulinkovich OG.Sviridov SV.Vasilevskii DA.Savchenko AI. Zh. Org. Khim. 1991, 27: 1428 -
4a
Kasatkin A.Sato F. Tetrahedron Lett. 1995, 36: 6079 -
4b
Lee J.Kim H.Cha JK. J. Am. Chem. Soc. 1996, 119: 4198 -
4c
Lee J.Kim YG.Bae JG.Cha JK. J. Org. Chem. 1996, 61: 4878 -
4d
Lee J.Kang CH.Kim H.Cha JK. J. Am. Chem. Soc. 1996, 119: 291 -
5a
Kulinkovich OG.de Meijere A. Chem. Rev. 2000, 100: 2789 -
5b
Sato F.Urabe H.Okamoto S. Chem. Rev. 2000, 100: 2835 - 6
Epstein OL.Kulinkovich OG. Tetrahedron Lett. 2001, 42: 3757 -
8a
Gibson DH.De Puy CH. Chem. Rev. 1974, 74: 605 -
8b
Kulinkovich, O. G. Chem. Rev. 2003, 103, in press.
-
9a
Savchenko AI.Kulinkovich OG. Russ. J. Org. Chem. (Engl. Transl.) 1997, 33: 846 -
9b
Chevtchouk TA.Kulinkovich OG. Russ. J. Org. Chem. (Engl. Transl.) 2000, 36: 1124 -
10a
Kulinkovich OG.Savchenko AI.Shevchuk TA. Russ. J. Org. Chem. (Engl. Transl.) 1999, 35: 225 -
10b
Chevtchouk TA.Isakov VE.Kulinkovich OG. Tetrahedron 1999, 55: 13205 - 11
Quan LG.Kim S.-H.Lee JC.Cha JK. Angew. Chem. Int. Ed. 2002, 41: 2160 - 12 The Fe- catalyzed ‘head-to-head’ coupling
of alkenes has been disclosed recently:
Small BL.Marcucci AJ. Organometallics 2001, 20: 5738 ; and references therein - 14
Kulinkovich OG.Epstein OL.Isakov VE.Khmel’nitskaya EA. Synlett 2001, 49 - 17
Epstein OL.Savchenko AI.Kulinkovich OG. Russ. Chem. Bull. 2000, 278 - 18
Kulinkovich OG. Pure Appl. Chem. 2000, 72: 1715 - 19
Wright WG.Warren FL. J. Chem. Soc., C 1967, 284
References
In some cases, diisopropoxytitanacyclopropane is more smoothly involved in olefin-exchange reactions than 2-substituted titanacyclopropane reagents (see ref. [6] ).
13Typical procedure: To a solution of homoallylic alcohol 1b (0.86 g, 10 mmol) in Et2O (15 mL) Ti(i-PrO)4 (1.5 mL, 5 mmol) and i-PrMgBr (20 mmol of 1.2-1.5 M solution in Et2O) were added consequently dropwise in 30 min at room temperature, and the mixture was stirred for an additional 30 min. After acidic work up (20 mL of 10% aq. H2SO4) and extraction with ethyl acetate, organic layers were washed with saturated NaHCO3 and brine, dried over MgSO4 and evaporated. 2,9-Decanediol 2b (containing near 10% of 4-methyl-2,8-nonanediol 3b by NMR and GC-MS-analysis) (0.61 g, 70%) was isolated by column chromatography on silica gel (eluent: cyclohexane-ethyl acetate). After two crystallisations (petroleum ether-benzene) 0.38 g of crystalline 2,9-decanediol 2b was obtained: mp 32-33 °C. (lit. [19] mp 33 °C); 1H NMR (400 MHz, CDCl3): δ = 1.17 (d, 6 H, J = 6.4 Hz), 1.20-1.48 (m, 12 H), 2.07 (br s, 2 H), 3.68-3.78 (m, 2 H); 13C NMR (100 MHz, CDCl3) δ = 23.33, 25.57, 29.48, 39.18, 67.89; MS (70 eV) 29, 45 (100%), 55, 69, 81, 96, 112, 123, 141, 155; IR (CCl4, cm-1) 3600.
15Selected NMR data of the reductive coupling products: 1-[6-(1-Hydroxycyclopentyl)hexyl]-1-cyclopentanol ( 2d): 13C NMR (100 MHz, CDCl3): δ = 23.79, 24.59, 30.18, 39.64, 41.47, 82.51. (2 E , 12 E )-2,12-Tetradecadiene-4,11-diol ( 2e): 1H NMR (400 MHz, CDCl3): δ = 1.20-1.38 (m, 8 H), 1.38-1.56 (m, 4 H), 1.67 (d, 6 H, J = 6.4 Hz), 1.72 (br s, 2 H), 3.98 (q, 2 H, J = 6.6 Hz), 5.40-5.48 (m, 2 H), 5.56-5.68 (m, 2 H); 13C NMR (100 MHz, CDCl3): δ = 17.56, 25.32, 29.42, 37.20, 73.00, 126.52, 134.38. 2,9-Dimethyl-2,9-decanediol ( 2c): 1H NMR (400 MHz, CDCl3): δ = 1.12-1.20 (m, 12 H), 1.24-1.36 (m, 4 H), 1.36-1.46 (m, 4 H), 1.50 (br s, 2 H); 13C NMR (100 MHz, CDCl3): δ = 24.22, 29.14, 30.09, 43.89, 70.90. 1,10-Decanediol ( 2g): 1H NMR (400 MHz, CDCl3): δ = 1.22-1.44 (m, 12 H), 1.48-1.64 (m, 4 H), 2.05 (br s, 2 H), 3.61 (t, 4 H, J = 6.6 Hz); 13C NMR (100 MHz, CDCl3): δ = 25.66, 29.31, 29.43, 32.67, 62.85. 2,11-Dodecanediol ( 2h): 1H NMR (400 MHz, CDCl3): δ = 1.17 (d, 6 H, J = 6.4 Hz), 1.24-1.50 (m, 16 H), 1.94 (br s, 2 H), 3.71-3.84 (m, 2 H); 13C NMR (100 MHz, CDCl3): δ = 23.34, 25.65, 29.44, 29.53, 39.25, 67.95.
16After acidic hydrolysis of the reaction products, diols 3b and 4,5-dimethyl-2,7-octanediol were obtained in 29% yield as an nearly equimolar mixture (GC-MS).