Radical reactions with double memory of chirality (2MOC) for the enantiospecific synthesis of adjacent stereogenic quaternary centers in solution: cleavage and bonding faster than radical rotation.

ABSTRACT: The solution photochemistry of bis(phenylpyrrolidinonyl)ketones (R,R)-1b and (S,S)-1b exhibited a remarkably high memory of chirality. Stereospecific decarbonylation to products (R,R)-3b and (S,S)-3b, respectively, occurred with an ee of ca. 80%. The reaction is thought to occur along the single state manifold by sequential Norrish type-I alpha-cleavage, decarbonylation, and radical-radical combination in a time scale that is comparable to that required for the radical intermediate to expose its other enantiotopic face by rotation about an axis perpendicular to that of the p orbital (ca. 3-7 ps). The absolute configuration of a key intermediate and that of ketone (R,R)-1b were determined by single-crystal X-ray diffraction and the ee values of the photochemical products with the help of ch

SUBMITTER: Resendiz MJ 

PROVIDER: S-EPMC4078905 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature