Asymmetric Synthesis of (S)-Homoproline and (S)-Homopipecolic Acid¹

Abstract

As for (S)—homoproline (3) there is a marked discrepancy between the directions of the optical rotation reported by two groups of chemists3,4. Here we wish to communicate novel asymmetric syntheses of (S)—homoproline (3) and (S)—homopipecolic acid (4) carried out in connection with our asymmetric cyclization studies². We also examined catalytic potentialities of these unnatural β-amino acids in asymmetric aldol cyclization.