Enantioselective reduction of ketophosphonates using chiral acid adducts with sodium borohydride
Authors: Nesterov, V.; Kolodyazhnyi, O.
Source: Russian Journal of General Chemistry, Volume 76, Number 7, July 2006 , pp. 1022-1030(9)
Publisher: MAIK Nauka/Interperiodica
Abstract:A method for asymmetric reduction of α-and -ketophosphonates using a chiral complex prepared from sodium borohydride and D-or L-tartaric acid is developed. Reduction of α-or -ketophosphonates by these reagents led to formation of corresponding (S)-or (R)-hydroxyphosphonates. Reduction of chiral di(1R,2S,5R)-menthylketophosphonates by the chiral complex NaBH4/(R,R)-tartaric acid due to the dual compliant asymmetric induction resulted in increased stereoselectivity of the reaction and led to formation of the hydroxyphosphonates with ee 90% or higher. On the other hand, reduction of di(1R,2S,5R)-methylketophosphonates by the chiral complex NaBH4/(S,S)-tartaric acid proceeded as non-compliant dual asymmetric induction and resulted in decreased reaction stereoselectivity leading to formation of hydroxyphosphonates with ∼45–60% ee. The developed methodology was applied to the synthesis of (R)-phosphocarnitine in multigram amounts.
Document Type: Research Article
Publication date: July 1, 2006