Enantiomerically pure cyclobutanols containing up to four chiral centers were synthesized applying a [2+2] cycloaddition between carbohydrate enol ethers and substituted ketenes. Acid-catalysed cleavage of the anomeric acetal linkage to the carbohydrate auxiliary gave (1R,2R,3S)-3-benzyloxy-2-methylcyclobutanol in high yield and under conservation of all generated chiral centers. The absolute configuration of the synthesized cyclobutanols was determined by single-crystal X-ray analysis.
通过
碳水化合物烯醇醚和取代酮之间的 [2+2] 环加成反应,合成了含有多达四个手性中心的对映体纯
环丁醇。通过酸催化裂解与
碳水化合物助剂的同分异构
乙缩醛连接,得到了(1R,2R,3S)-3-苄氧基-2-甲基
环丁醇,产量很高,而且所有生成的手性中心都保持不变。合成的
环丁醇的绝对构型是通过单晶 X 射线分析确定的。