Rhodium-catalyzed enantioselective conjugate addition of organoboronic acids to alpha,beta-unsaturated sulfones.
[reaction: see text] A general method for the enantioselective catalytic conjugate addition to acyclic alpha,beta-unsaturated sulfones is described. Using metal-chelating alpha,beta-unsaturated pyridyl sulfones as substrates, the rhodium-catalyzed chiraphos-mediated addition of organoboric acids takes place in excellent yield and high enantioselectivity. The subsequent elimination of the pyridylsulfonyl group by Julia-Kociensky olefination provides a novel approach to the enantioselective synthesis of allylic substituted alkenes.
Departamento de Química Orgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco 28049 Madrid, Spain.
Pablo
P
Mauleón
Juan C
JC
Carretero