A Systematic Study of the Hydride Reduction of Cyclopropyl Ketones with Structurally Simplified Substrates. Highly Stereoselective Reductions of <i>Trans</i>-Substituted Cyclopropyl Ketones via the Bisected <i>s</i>-<i>Cis</i> Conformation
作者:Yuji Kazuta、Hiroshi Abe、Tamotsu Yamamoto、Akira Matsuda、Satoshi Shuto
DOI:10.1021/jo030019v
日期:2003.5.1
stereoselective hydride reduction of the cis- and trans-substituted cyclopropyl ketones was systematically investigated using a series of structurally simplified substrates, trans-[tert-butyldiphenylsilyloxymethyl]cyclopropyl ketones 1a-e and trans-(benzyloxymethyl)cyclopropyl methyl ketone (2), and the corresponding cis congeners 3a,b,e and 4. The results showed that, not only in the reduction of the cis-substituted
基于环丙基酮的密度泛函理论(DFT)的从头算计算表明(1)等分的s-顺式和s-反式构象异构体是仅有的两个最小能量构象异构体,而s-顺式构象异构体比s稳定。 -反式和(2)酰基部分中的大体积烷基和环丙烷环上的顺式取代基使平分的s-顺式构象异构体更加稳定。基于这些计算和实验结果,很可能底物的一分为二的s-顺式构象异构体越稳定,氢化物还原的立体选择性就越大。因此,立体化学可以通过氢化物从受阻较少的面上对基底的一分为二的s-顺式构象的攻击来解释。立体化学结果的可预测性基于等分的s-顺式过渡态模型,