Highly enantioselective synthesis of pipecolic acid derivatives via an asymmetric aza-Diels–Alder reaction
作者:Patrick D. Bailey、Derek J. Londesbrough、Timothy C. Hancox、John D. Heffernan、Andrew B. Holmes
DOI:10.1039/c39940002543
日期:——
Very high asymmetric induction is observed in the aza-DielsâAlder reaction between dienes and the imine (R)-PhMeCHâNCHCO2PhMen*(where PhMen*= 8-phenylmenthyl), which bears matched auxiliaries on nitrogen and on the ester; reactions in trifluoroethanol, in the presence of trifluoroacetic acid (1 equiv.), give substituted pipecolic acid derivatives in ca 50% isolated yield, with only a single regio- and diastereo-isomer of the cycloadduct detectable in all cases (d.e.>95%).
在二烯和亚胺 (R)-PhMeCH-NCHCO2PhMen*(其中 PhMen*= 8-苯基薄荷基)之间的氮杂-狄尔斯-阿尔德反应中观察到非常高的不对称诱导,亚胺在氮和酯上带有匹配的助剂;在三氟乙酸(1 当量)存在下,在三氟乙醇中进行反应,得到取代的哌可酸衍生物,分离产率约为 50%,在所有情况下仅可检测到环加合物的单一区域异构体和非对映异构体(d.e>95%) )。