3-Chloronorbornenone (R)-1a (98% ee) was obtained from trichloronorbornene 5 in two steps by the in situ generation of dichloronorbornadiene 2a with t-BuOK and desymmetrization with (-)-ephedrine, followed by hydrolysis with PPTS. The generality of this desymmetrization with (-)-ephedrine was tested with dibromonorbornadiene 2c and other substituted dichloronorbornadienes.
Dipartimento di Scienze Ambientali and Dipartimento di Chimica, Università Ca' Foscari di Venezia, Dorsoduro 2137, I-30123 Venezia, Italy. gborsato@unive.it
