Enantioselective Synthesis of Bicyclo[4.4.1]undecane-2,7-dione via Samarium(II)-Mediated Fragmentation of a Cyclopropane Precursor
作者:Hans-Günther Schmalz、Sherif El Sheikh、Nina Kausch、J. Lex、J.-M. Neudörfl
DOI:10.1055/s-2006-941599
日期:2006.6
An efficient six-step synthesis of bicyclo[4.4.1]undecane-2,7-dione was elaborated. Key steps include an enantioselective oxazaborolidine-catalyzed borane reduction (CBS reduction) of 2,3,4,6,7,8-hexahydronaphthalene-1,5-dione to the corresponding diol, and a subsequent (syn-diastereoselective) cyclopropanation. Oxidation then gives tricyclo[4.4.1.0 1,6 ]undecane-2,7-dione (>99% ee) which on treatment
详细阐述了双环[4.4.1]十一烷-2,7-二酮的高效六步合成。关键步骤包括对映选择性 oxazaborolidine 催化的 2,3,4,6,7,8-六氢萘-1,5-二酮到相应二醇的硼烷还原(CBS 还原),以及随后的(syn-非对映选择性)环丙烷化。然后氧化得到三环[4.4.1.0 1,6 ]十一烷-2,7-二酮(>99% ee),用两当量的碘化钐(II)处理后,中心环丙烷键断裂,得到目标化合物立体化学信息的任何丢失。