Complementary routes to both enantiomers of pipecolic acid and 4,5-dihydroxypipecolic acid derivatives

Complementary new routes to both enantiomers of N-protected pipecolic acid and the corresponding 4,5-dihydroxylated derivatives are developed, which involve stereo-divergent allylation of a chiral N-allylimine and ring-closing metathesis as key steps.