一系列exo -7-烷基双环[3.2.0]庚-2-烯的整体分解速率常数(k d)相对不变。对于烷基取代基乙基,丙基,丁基,异丙基和叔丁基,[1,3]σ重排的速率常数与断裂速率常数的比率k 13 / k f明显低于k 13 / k f = 150,对于exo -7-甲基双环[3.2.0]庚-2-烯。无论烷基的大小和质量如何,[1,3]碳迁移的立体选择性在表面转化率80%至89%时都相当稳定(si),这与角动量守恒相符,但与轨道对称性守恒相符。总体结果与Carpenter和合作者普遍支持[1,3]σ重排的“动态匹配”现象相对应。
一系列exo -7-烷基双环[3.2.0]庚-2-烯的整体分解速率常数(k d)相对不变。对于烷基取代基乙基,丙基,丁基,异丙基和叔丁基,[1,3]σ重排的速率常数与断裂速率常数的比率k 13 / k f明显低于k 13 / k f = 150,对于exo -7-甲基双环[3.2.0]庚-2-烯。无论烷基的大小和质量如何,[1,3]碳迁移的立体选择性在表面转化率80%至89%时都相当稳定(si),这与角动量守恒相符,但与轨道对称性守恒相符。总体结果与Carpenter和合作者普遍支持[1,3]σ重排的“动态匹配”现象相对应。
Free-radical ring expansion of fused cyclobutanones: stereospecific construction of 5,7-, 6,7-, 7,7-, 8,7-, and 5,8-cis-fused bicyclic systems
作者:Paul Dowd、Wei Zhang
DOI:10.1021/jo00052a034
日期:1992.12
A new method of appending seven- and eight-membered rings to cycloalkenes is described. Treatment of selected alkene precursors with an omega-bromoalkyl ketene or a keteniminium salt leads to haloalkyl cyclobutanone formation. Tri-n-butyltin hydride promoted ring expansion then yields the annulated product. Since the initial cyclobutanone is cis fused, the final product is also produced stereospecifically with a cis ring fusion.