Amplification of anti-diastereoselectivity via Curtin-Hammett effects in ruthenium-catalyzed hydrohydroxyalkylation of 1,1-disubstituted allenes: diastereoselective formation of all-carbon quaternary centers.

ABSTRACT: Under the conditions of ruthenium-catalyzed transfer hydrogenation, 1,1-disubstituted allenes 1a-c and alcohols 2a-g engage in redox-triggered generation of allylruthenium-aldehyde pairs to form products of hydrohydroxyalkylation 3a-g, 4a-g, and 5a-g with complete branched regioselectivity. By exploiting Curtin-Hammett effects, good to excellent levels of anti-diastereoselectivity (4:1 to >20:1) are obtained. Thus, all carbon quaternary centers are formed in a diastereoselective fashion upon carbonyl addition from the alcohol oxidation level in the absence of premetalated nucleophiles or stoichiometric byproducts. Exposure of allene 1b to equimolar quantities of alcohol 2a and aldehyde 6b under standard reaction conditions delivers adducts 4a and 4b in a 1:1 ratio. Similarly, exposure of a

SUBMITTER: Zbieg JR 

PROVIDER: S-EPMC3030639 | biostudies-literature | 2011 Feb

REPOSITORIES: biostudies-literature