Synthesis of five-membered lactams by α-carbamoyl radical cyclisations
Synthesis of five-membered lactams by α-carbamoyl radical cyclisations
复制标题
α-氨基甲酰自由基环化合成五元内酰胺
DOI：
10.1039/p19890000879
复制
发表时间：
1989
期刊：
影响因子：
--
通讯作者：
M. Ikeda
中科院分区：
文献类型：
--
作者：
Tatsunori Sato;Y. Wada;M. Nishimoto;H. Ishibashi*;M. Ikeda
由三丁基锡自由基介导的碳-氯或碳-硫键断裂产生的N-烯丙基-α-氨基甲酰基的自由基环化已经得到了一些详细的研究。在α位被甲硫基（苯硫基）、氯、甲基、苯基、甲氧基或乙酰氧基取代的基团以5-exo-trig方式顺利环化，得到以反式异构体为主的五元内酰胺。相反，N-或α-未取代的、或α-磺酰基取代的基团主要或排他地产生还原产物。 N-β-甲基烯丙基系统的环化再次进行区域选择性，得到五元内酰胺。
Free-radical cyclisation of N-allyl-α-carbamoyl radicals generated by tributyltin radical-mediated cleavage of carbon–chlorine or carbon–sulphur bonds has been studied in some detail. The radicals substituted at the α position by methylthio (phenylthio), chloro, methyl, phenyl, methoxy, or acetoxy groups underwent smooth cyclisation in a 5-exo-trig manner to give five-membered lactams in which the trans-isomer predominated. In contrast, the N- or α-unsubstituted, or α-sulphonyl-substituted, radicals gave predominantly or exclusively the reduction products. Cyclisation of the N-β-methylallyl system proceeded again regioselectively to give the five-membered lactam.