Department of Chemistry, Fudan University, Shanghai 200433, China.
J Org Chem. 2009 Nov 20;74(22):8610-5. doi: 10.1021/jo9017099.
We have developed a strategy for constructing nitrogen heterocycles by photoinduced PhSe group transfer radical cyclization. trans-Alpha,beta-disubstituted gamma-butyrolactams (2-pyrrolidinones) were prepared in good yields (38-73%) with high regioselectivity and stereoselectivity from N-alkenyl alpha-PhSe beta-keto amides. Reaction outcomes were modulated by the steric effect of the substituents on the nitrogen atom of the cyclization precursors and the stereoelectronic effect of the substrates. Diphenyldiselenide, as an additive, was found to promote ring closure. The advantage of this strategy in natural product synthesis is demonstrated by a formal synthesis of (+/-)-isocynometrine.
我们开发了一种通过光诱导 PhSe 基团转移自由基环化来构建氮杂环的策略。通过 N-烯基α-PhSeβ-酮酰胺，高区域选择性和立体选择性地得到了顺式，反式-α，β-二取代γ-丁内酯（2-吡咯烷酮），产率为 38-73%。反应结果受环化前体氮原子上取代基的空间效应和底物的立体电子效应的调节。二苯基二硒醚作为添加剂，被发现促进环闭合。通过（±）-异辛可宁的形式合成，证明了该策略在天然产物合成中的优势。
