α-Phosphorus(V)-Substituted Ylides

Practical and Highly Selective Sulfur Ylide-Mediated Asymmetric Epoxidations and Aziridinations Using a Cheap and Readily Available Chiral Sulfide: Extensive Studies To Map Out Scope, Limitations, and Rationalization of Diastereo- and Enantioselectivities

“…In the search for a suitable chiral sulfide, we were attracted to the little-known bicyclic compound isothiocineole 2 , as it seemed to fulfill many of the criteria established as desirable. , In terms of enantioselectivity (Scheme ): Its rigid bicyclic structure would dictate the position of the ylide substituent in relation to the sulfide scaffold (lone pair selectivity); Its rigid bicyclic structure would control the conformation of the ylide through nonbonded steric interactions; One of the two gem -dimethyl groups should block one face of the ylide leading to high enantioselectivity. …”

“…The direct asymmetric transformation of carbonyl compounds into epoxides using chiral sulfur ylides offers a complementary and potentially advantageous method over the two-step protocol of Wittig olefination followed by asymmetric epoxidation. − However, despite its appeal and over 30 years of research, the methodology has rarely been used. Herein, we detail results that make the sulfur ylide disconnection a genuine alternative to alkene epoxidation for practical asymmetric epoxidation, which can be incorporated into a synthetic plan with confidence.…”