Rule of five cyclizations in 5-hexenyl radicals and photocycloadditions of 1,5-hexadienes: effect of 4-oxa substitution
作者:Albert R. Matlin、Karen Feit Brinton、Belinda Tsao Nivaggioli
DOI:10.1002/poc.1120
日期:2007.2
The effect of 4-oxa substitution on the regiochemistry and rate of 5-hexenyl radical cyclizations was investigated, as a potential model for [2 + 2] photocycloadditions of 2-acyl-4-oxa-1,5-hexadienes. Increasing the electron density in the alkene decreases the rate of cyclization in the 4-oxa-hexenyl radicals, relative to the all carbon analogs, but has little effect on the regioselectivity of the
研究了4-氧杂取代对区域化学反应和5-己烯基自由基环化速率的影响,以此作为2-酰基-4-氧杂-1,5-己二烯[2 + 2]光环加成反应的潜在模型。相对于所有碳类似物,增加烯烃中的电子密度会降低4-氧杂己烯基中环化的速率,但对环化的区域选择性影响很小。自由基模型不能重现1,6的高度封闭,这是在4-oxa-1,5-己二烯1a的[2 + 2]光环加成反应中观察到的。但是,自由基模型的确加强了这样的解释,即远离反应中心进行取代所产生的基态构象效应对环化反应具有重要的速率影响。版权所有©2007 John Wiley&Sons,Ltd.