ChemInform Abstract: Stereoselectivity in Reactions of 1,2-Dioxy-Substituted Radicals under Chelation Control: An Unexpected Result.

✍ Scribed by M. GERSTER; K. SCHENK; P. RENAUD

• Publisher: John Wiley and Sons
• Year: 2010
• Weight: 32 KB
• Volume: 28
• Category: Article
• ISSN: 0931-7597
• DOI: 10.1002/chin.199706031

✦ Synopsis

1997 stereochemistry stereochemistry (general, optical resolution) O 0030 06 -031 Stereoselectivity in Reactions of 1,2-Dioxy-Substituted Radicals under Chelation Control: An Unexpected Result.

-It is shown that the strong pyramidalization of the radical intermediates is the reason why anti Cram chelation products are obtained in the reduction of 1,2-dialkyl-1,2dioxy-substituted radicals. The conversion of (VII) in the hydrostannylation is not stereoselective in the absence of an additive, however, under conditions B) by treatment with AlMe3 the reaction is highly stereoselective with unexpected preferential formation of the "like" isomer. Other additives are less efficient. In conclusion, it is demonstrated that substitution at the Cl position of 1,2-dioxysubstituted radicals is of critical importance for the sense of stereoselectivity during chelation-controlled reactions.

-(GERSTER, M.; SCHENK, K.;