Synthesis of 4,6-Dideoxyfuranoses through the Regioselective and Diastereoselective Oxyfunctionalization of a Dimethylphenylsilyl-Substituted Chiral Homoallylic Alcohol

• Published in: Journal of organic chemistry 2001-11, Vol.66 (22), p.7365-7371
• Main Authors: Adam, Waldemar, Saha-Möller, Chantu R, Schmid, Katharina S
• Format: Article
• Language: English
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo010549w

The 4,6-dideoxyfuranoses 10a and 10b have been synthesized by starting from the readily available E-5-dimethylphenylsilyl-2-hexene-4-ol (1) and employing successively three versatile oxyfunctionalization methods, namely photooxygenation, metal-catalyzed epoxidation, and oxidative desilylation. Photooxygenation of the hydroxy vinylsilane 1 and subsequent triphenylphosphine reduction of the hydroperoxides 3 afford the like-4a and unlike-4b diols, which have been converted separately to the tetrahydrofurans (2S*,3R*,5R*)-7a and (2S*,3R*,5S*)-7b by a combination of diastereoselective epoxidation and regioselective intramolecular epoxide-ring opening. In the epoxidation reaction, catalyzed by Ti(OiPr)4 or VO(acac)2, only one diastereomer (dr >95:5) of the epoxide 5 is obtained. Further intramolecular opening of the epoxide ring in erythro-5 occurs regioselectively at the C-α position and diastereoselectively under inversion of the configuration of the silyl-substituted stereogenic center to generate only one diastereomer of the tetrasubstituted tetrahydrofurans 7. Oxidative desilylation of the latter gave the hitherto unknown 4,6-dideoxyfuranoses 10a and 10b. The use of the optically active E-5-dimethylphenylsilyl-2-hexene-4-ol (1) as starting material, which is readily available through lipase-catalyzed kinetic resolution, leads to the d- and l-4,6-dideoxysorbofuranoses 10a and d- and l-4,6-dideoxyfructofuranoses 10b in up to 98% enantiomeric excess.