Convenient Synthesis of Ethenylcyclopropane and Some 2-Cyclopropylcyclopropane Derivatives¹
作者:Armin de Meijere、Valentin Rassadin、Viktor Sokolov、Alexander Khlebnikov、Nikolay Ulin、Sergei Kozhushkov
DOI:10.1055/s-0031-1289600
日期:2012.2
diazoacetate gave ethyl 2-cyclopropylcyclopropanecarboxylate (cis/trans-9, ratio 1:1.4) in 80% yield. The latter was also prepared in 79% overall yield by sequential cyclopropanation of buta-1,3-diene with ethyl diazoacetate [under Rh2(OAc)4 catalysis] and diiodomethane/diethylzinc/trifluoroacetic acid. Curtius degradation of 2-cyclopropylcyclopropanecarboxylic acid (obtained by hydrolysis of the ester) gave
由环丙基甲基酮(1)分为四个简单,易于扩展的步骤(溴化,还原为溴代醇,乙酰化,以及用Zn / Cu还原消除)制得乙烯基环丙烷(5),总产率为56%。1-溴-2-环丙基环丙烷(7)(约1:1种混合物的顺式-和反式- 7)制备5经由二溴化物6,并从7硼酸顺/反式- 8(比例1:1)中的溶液得到96%的产率。铑(II)催化的5的环丙烷化 用重氮基乙酸乙酯,得到2- cyclopropylcyclopropanecarboxylate(顺式/反式- 9在80%的产率:1.4,比1)。后者也可以通过用重氮乙酸乙酯(在Rh 2(OAc)4催化下)和二碘甲烷/二乙基锌/三氟乙酸进行顺丁烯-1,3-二烯的连续环丙烷化制得,总收率为79%。将2-环丙基环丙烷羧酸进行曲度降解(通过酯水解获得),以58%的收率得到2-环丙基环丙胺(顺式和反式异构体的1:1.2混合物)。 溴化-还原-消除-烯烃-环丙烷化-小环