ASYMMETRIC REACTIONS USING NONNATURAL CHI RAL AUXILIARIES

In recent years, the development of chiral auxiliaries has been attrac ting much attention. Although many of these are usually derived from n atural chiral compounds, limitations in their structural modification are sometimes an obstacle to achieve an efficient asymmetric process. This problem would be solved by using non-natural chiral compounds due to their two favorable characteristics in contrast to natural product s and their derivatives: 1) Both enantiomers are readily available and can be used in asymmetric reactions. 2) The structure can be freely d esigned. In the preparation of well-designed, non-natural chiral auxil iaries, the optical resolution of their racemic modifications is thoug ht to be one of the most practical methods. In this context, the devel opment of an efficient method for the optical resolution of a racemic modification is considered to be essential. We have been carrying out a study which was coherent with the design, optical resolution, and ap plication of non-natural chiral auxiliaries. In this review we would l ike to describe our recent results concerning the development of new n on-natural chiral auxiliaries as well as their application to asymmetr ic syntheses.