Synthesis of non-natural cyclic amino acids from available unsaturated tertiary amines

Abstract

New approach is developed to the synthesis of cyclic amino acids derivatives. Unsaturated tertiary amines react with ethyl diazoacetate under the catalysis by copper catalyst Cu(F3acac)2 leading to the formation of products of [2,3]-sigmatropic rearrangement which via the metathesis of double bonds undergo a ring closure. The subsequent hydrogenation of compounds obtained furnished esters of 6- and 7-membered cyclic α-amino acids. Besides the racemic also optically active compounds were obtained, in particular, esters of (R)- and (S)-pipecolic acid.