Pinane-Type Tridentate Reagents for Enantioselective Reactions: Reduction of Ketones and Addition of Diethylzinc to Aldehydes
作者:Yie-Jia Cherng、Jim-Min Fang、Ta-Jung Lu
DOI:10.1021/jo982403b
日期:1999.4.1
pinane-based diols 5-9 as promoters gave 1-phenylpropanol in favor of the S enantiomer up to 88% ee. Using the pinane-based alcohols 10a-e as promoters, the R enantiomer was obtained as the major product. The addition reactions of diethylzinc to various substituted benzaldehydes, employing the diol ligands 5c and 8e, afforded predominantly the corresponding (S)-alcohols. The chiral modifiers 5-10 were
用(1R,2S,3S,5R)-(+)-10-苯胺基-3-乙氧基-2-羟基pin烷(10b)改性的氢化铝锂还原芳基和烯基甲基酮可在83-96中获得手性仲醇%的化学产率和50-91%的ee,其中R对映异构体占优势。在碘化锂的存在下苯乙酮的还原得到具有较高ee的醇产物。另一方面,使用基于pin烷的二醇5-9作为促进剂,二乙基锌与苯甲醛的加成反应得到1-苯丙醇,有利于S对映异构体,其ee高达88%。使用基于the烷的醇10a-e作为促进剂,获得R对映异构体作为主要产物。使用二醇配体5c和8e,二乙基锌与各种取代的苯甲醛的加成反应主要得到相应的(S)-醇。由(1R)-(-)-肉豆蔻醇制备手性改性剂5-10,并且在不对称反应后易于回收(> 90%)。在这项研究中,LAH还原和Et(2)Zn的添加是制备光学活性仲醇的补充方法。配体10-丁基苯胺基-2,3-二羟基pin烷5c有效地促进了Et(2)Zn的添