Diastereoselective synthesis of chiral α-aminoorganotributyltins via ring-opening of 2-tributylstannyloxazolidines
作者:Vincent Coeffard、Jean-Christophe Cintrat、Erwan Le Grognec、Isabelle Beaudet、Jean-Paul Quintard
DOI:10.1016/j.jorganchem.2005.11.070
日期:2006.4
Reactions of 2-tributylstannyloxazolidines 2a-d (cis or trans), derived from (R)-phenylglycinol protected as N-carbamate, with lithium diorganocuprates in presence of boron trifluoride in diethyl ether provide the corresponding functionalized tributylstannyl-alpha-aminoalcohols 3-10 with diastereoselectivities close to 85:15 in favour of the (S,R)-isomer. The stereochemical trend is preserved using allyltributyltin as nucleophile and TiCl2(Oi-Pr)(2) as Lewis acid in dichloromethane. The assignments of the (S,R) or (RR) configurations in 3-10 were achieved on the basis of physicochemical data combined with a radiocrystallographic structure. Stereochemical preferences were rationalized by consideration of the interactions occurring in the iminium intermediates. (c) 2005 Elsevier B.V. All rights reserved.