Preparation of Camphor-Derived Oxazaborolidines and the Application to Reduction of Ketones

• Main Authors: Chien-Hung Shen, 沈建宏
• Other Authors: Chi-Tung Hsu
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/42641357241703575760

碩士 === 朝陽科技大學 === 應用化學系碩士班 === 97 === In order to obtain an excellent and cheaper chiral ligand for borane reduction, we have synthesized some new oxazaborolidines, starting from camphor, which is an inexpensive and readily available natural product. At first, the camphor-derived formyl [2.2.1]bicyclic carbinol was prepared. Then, the reaction of the bicyclic carbinol with some primary amines provided regio-specific [3.2.1]bicyclic amino ketones. Treatment of bicyclic amino ketones with sodium borohydride produced stereospecific [3.2.1]bicyclic amino alcohol. The separate reactions of boroxine and borane with [3.2.1]bicyclic amino alcohol, then, afforded new oxazaborolidines, which were immediately used as chiral auxiliaries for the asymmetric reduction of some prochiral ketones to give stereospecific secondary alcohols. The secondary alcohols were obtained in 85 ~ 97 % yield with >99 % ee under the best reduction conditions.