2‑Vinyl Threoninol Derivatives via Acid-Catalyzed Allylic Substitution of Bisimidates

A diastereoselective
synthesis of 4-vinyl oxazolines syn-2 was developed based on an acid-catalyzed cyclization of bistrichloroacetimidates
(E)-1. The reaction likely involves
an allyl carbenium ion intermediate in which the adjacent stereocenter
directs the stereoselectivity for C–N bond formation. Oxazolines syn-2 were transformed to C-quaternary threoninol,
threoninal, and threonine derivatives which can be further incorporated
into complex natural compounds.