An efficient method for the diastereoselective synthesis of α-fluoro-β-hydroxy esters based on the radical reduction of α-bromo-α-fluoro-β-hydroxy esters
作者:Kazuhide Mima、Takashi Ishihara、Saki Kuwahata、Tsutomu Konno、Hiroki Yamanaka
DOI:10.1016/s0040-4020(02)00119-9
日期:2002.3
−15°C for 0.5 h and with tributyltin hydride in the presence of a catalytic amount of triethylborane at −15°C for 4 h, the corresponding threo-α-fluoro-β-hydroxyalkanoates were obtained highly diastereoselectively in good yields. On the other hand, the α-bromo-β-hydroxy esters having an aromatic substituent were subjected to the reaction with tris(trimethylsilyl)silane in the presence of a catalytic amount
当使α-溴-α-氟-β-羟基酯与甲苯中的三甲基铝在-15°C下连续反应0.5小时,并在催化量的三乙基硼烷存在下与氢化三丁基锡在-15°C下连续反应4小时。 h,以高产率非对映选择性地获得相应的苏-α-氟-β-羟基链烷酸酯。另一方面,使具有芳香族取代基的α-溴-β-羟基酯在催化量的三乙基硼烷在THF中在-78℃下与三(三甲基甲硅烷基)硅烷反应10小时,从而得到相应的具有高赤型的赤型-α-氟-β-羟基链烷酸酯-选择性具有良好的收率,但是带有脂族取代基的那些几乎以非立体选择性的方式被还原。