Straightforward entry to the pipecolic acid nucleus. Enantioselective synthesis of baikiain

New enantioselective syntheses of N-protected baikiain and pipecolic acid have been developed. The starting material is 2,3-epoxy-5-hexen-1-ol (4) readily available in high ee by Sharpless epoxidation. The regio- and stereoselective epoxide ring-opening by allylamine afforded a doubly unsaturated amine that was converted into a carbamate (Boc) and submitted to ring-closing metathesis. The resulting cyclic amino diol 6 is a key intermediate that was converted into N-Boc-baikiain and several pipecolic acid derivatives.