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 asymm etric Michael addition reaction of phenylthioalcohol with liquid epime ric 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 sepa rated by means of preferential cyrstallization, which gave one optical ly pure compound 4b with de> 98%. The absolute configuration of 4b was established by X-ray crystallography. The method provided a new effic ient route for utilizing natural chiral auxiliaries and preparing opti cally pure diastereoisomeric compounds based on liquid epimers.