Enantioselective total syntheses of (+)-decursin and related natural compounds using catalytic asymmetric epoxidation of an enone
作者:Tetsuhiro Nemoto、Takashi Ohshima、Masakatsu Shibasaki
DOI:10.1016/s0040-4020(03)00861-5
日期:2003.8
The enantioselective total syntheses of (+)-decursin (1) and related natural dihydropyranocoumarins (−)-prantschimgin (3), (+)-decursinol (4), and (+)-marmesin (5) were achieved for the first time using catalytic asymmetric epoxidation of an enone as the key step. Catalytic asymmetric epoxidation of the enone was effectively promoted by the novel multifunctional asymmetric catalyst generated from La(O-i-Pr)3
首次实现(+)-地精(1)和相关天然二氢吡喃香豆素(-)-花木素(3),(+)-地精醇(4)和(+)-marmesin(5)的对映选择性合成使用烯酮的催化不对称环氧化作为关键步骤。由La(O- i- Pr)3,BINOL和Ph 3 As generatedO以1:1:1的比例生成的新型多功能不对称催化剂可有效促进烯酮的催化不对称环氧化,以94%的收率得到环氧化物和96%ee,将其重结晶得到光学纯的环氧化物。转换为通用关键中间体(-)-二十二烷醇(7),所有天然的二氢吡喃香豆素都是通过钯催化的分子内C-O偶联反应合成的。基于X射线分析,激光解吸/电离飞行时间质谱,动力学研究和不对称扩增研究,还描述了烯类催化不对称环氧化的可能反应机理。