Synthesis and crystal structure of a novel chiral compound prepared from (-)-borneol as a natural chiral auxiliary

The solid diastereoisomeric mixture 4a+4b was obtained via the asymmetric Michael addition reaction of phenylthioalcohol with liquid epimeric mixture 5\|( )\|bornyloxy\|2(5H)\|furanone 3a+3b, which was prepared by reaction of the natural abundant chiral auxiliary borneol 2 with 5\|hydroxy\|2(5H)\|furanone 1. The two diastereoisomers 4a+4b were separated by means of preferential cyrstallization, which gave one optically pure compound 4b with de>98%. The absolute configuration of 4b was established by X\|ray crystallography. The method provided a new efficient route for utilizing natural chiral auxiliaries and preparing optically pure diastereoisomeric compounds based on liquid epimers.

The solid diastereoisomeric mixture4a+4b was obtained via the asymmetric Michael addition reaction of phenylthioalcohol with liquid epimeric mixture 5-(-)-bornyloxy-2(5H)-furanone3a+3b, which was prepared by reaction of the natural abundant chiral auxiliary borneol 2 with 5-hydroxy-2(5H)-furanone 1. The two diastereoisorners4a +4b were separated by means of preferential cyrstallization, which gave one optically pure compound4b with de > 98 %. The absolute configuration of4b was established by X-ray crystallography. The method provided a new efficient route for utilizing natural chiral auxiliaries and preparing optically pure diastereoisomeric compounds based on liquid epimers.