Asymmetric Diels–Alder cycloaddition of a di- P-stereogenic dienophile with cyclopentadiene

Abstract

The Diels–Alder cycloaddition of the di- P-stereogenic dienophile ( S P, S P)- 1 leads to novel di- P-stereogenic norbornene derivatives and proceeds with moderate diastereoselectivity in the absence of a catalyst. In the presence of TiCl 4, however, the diastereoselectivity was raised to 9:1. The major diastereoisomer has been characterized crystallographically. The separation of the diastereomeric cycloadducts was possible by fractional crystallization in the presence of (−)- O, O-dibenzoyltartaric acid monohydrate.