Homochiral ketals in organic synthesis. Diastereoselective cyclopropanation of α,β-unsaturated ketals derived from 1,4-D1-O-benzyl-l-threitol
作者:Eugene A. Mash、Keith A. Nelson
DOI:10.1016/s0040-4020(01)90002-x
日期:——
2-Cycloalken-1-one 1,4-di --benzyl -L-threitol ketals undergo efficient and diastereoselective cyclopropanation when treated with an excess of the Simmons-Smith reagent. For example, 2-cyclohexen-1-one 1,4-di --benzyl -L-threitol ketal gave in 90-98% yield a 9:1 mixture of diastereomeric cyclopropanes as established by 62.9 MHz 13C NMR spectroscopy and by hydrolysis of the mixture to (1,6)-bicyclo[4
当用过量的Simmons-Smith试剂处理时,2-Cycloalken-1-one 1,4-二--苄基-L-苏糖醇缩酮会发生高效且非对映选择性的环丙烷化。例如,由62.9 MHz 13 C NMR光谱法和水解确定,2-环己烯-1-酮1,4-二-苄基-L-苏糖醇缩酮的收率为90-98%,为非对映体环丙烷的9:1混合物将混合物制成(1,6 )-双环[4.1.0]庚烷-2-酮。给出了十六个其他实例,这些实例证明了2-环烯-1-酮缩酮的制备方法的一般性和可预测性,因为不幸的是,它对α,β-不饱和1,4-二-苄基-L-苏糖醇缺乏非对映选择性乙缩醛。