Malonate radical cyclisations of methylenecyclopropane derivatives
摘要:
Cyclisations of various methylenecyclopropyl substituted malonate radicals have been studied. Radicals derived from malonates 4 and 9 underwent exclusive 5-exo cyclisation onto the methylenecyclopropane alkene, followed by opening of the resulting cyclopropylmethyl radical, to give methylenecyclohexane products. Radicals derived from malonates 5 and 10 largely gave bicyclo[1.5.0]octane products, in good yields, as a result of 7-endo cyclisation. Cyclisation of the radical derived from malonate 11 gave a bicyclo[1.5.0]nonane derivative in 31% yield, as a result of an 8-endo cyclisation.
由醇6a-c和12a,b分别分两步制备在三元环或亚甲基环丙烷或双环亚丙基部分的双键上具有炔基取代基的三甲基甲硅烷基保护的炔烃9a-c和14a,b通过转化为碘化物并与(三甲基甲硅烷基)乙炔化锂(8)偶联,总产率为38-73%。通过锂化,然后与(5-碘戊-1-炔基)三甲基硅烷(11)偶合,直接从双环亚丙基(3)以49%的收率合成双环亚丙基衍生物9d。通过用甲醇中的K 2 CO 3处理使烯炔9b-d被蛋白去甲硅烷基化,分别以53、74和94%的产率得到相应的未保护的烯炔10b-d。通过维蒂希烯化反应由羰基衍生物15a-c合成具有与炔基部分相邻的羰基的烯炔17a-c,然后分别以8、47、18和12%的总收率偶联8。亚甲基环丙烷衍生物在环(9a,b和10a)以及双键(14a,b及其原位制备的丙二甲硅烷基化的类似物)上具有取代基的Pauson-Khand反应通过搅拌相应的烯炔与[ Co2(CO)8]在
Lewis acid mediated cyclisation of methylenecyclopropyl ketones and aldehydes
作者:Guillaume L.N. Peron、John Kitteringham、Jeremy D. Kilburn
DOI:10.1016/s0040-4039(99)00320-2
日期:1999.4
The Lewis acid mediated cyclisation of various methylenecyclopropyl ketones, ketals and aldehydes has been investigated as a new route to six- and seven-membered rings. Cyclisation of aldehyde 6, ketal 9 and ketone 11 with TiCl4 gave cyclohexene products, and cyclisation of ketal 10 gave a dichlorocycloheptene, all via nucleophilic addition of the methylenecyclopropyl π bond to the activated carbonyl