Regioselective Synthesis of 1-Bromo-1,4-dienes by Free-Radical-Mediated Bromoallylation of Activated Acetylenes
作者:Takashi Kippo、Takahide Fukuyama、Ilhyong Ryu
DOI:10.1021/ol1016096
日期:2010.9.17
The free-radical-mediated bromoallylation of acetylenes proceeded efficiently in the presence of V-65 (2,2-azobis(2,4-dimethylvaleronitrile)) as the radical initiator. The regioselective reaction, which yields 1-bromo-2-substituted 1,4-dienes, is complementary to the Pd-catalyzed bromoallylation reaction previously reported by Kaneda. The products of the free-radical-mediated bromoallylation of acetylenes could be converted into a variety of substituted dienes by subsequent Pd-catalyzed reactions.
Radical bromoallylation of alkynes leading to 1-bromo-1,4-dienes
The full scope (30 examples) of the radical bromoallylation of alkynes using allyl bromides was studied. In this reaction, bromineradical adds to alkynes to form vinyl radicals, which then undergo an SH2′ reaction with allyl bromides to produce good yields of 1-bromo-1,4-dienes with the liberation of a bromineradical, which creates a radical chain. The sp2-carbon–bromine bond of the product dienes
研究了使用烯丙基溴对炔烃进行自由基溴代烯丙基化的全部范围(30个实例)。在该反应中,溴自由基加成炔基,形成乙烯基自由基,然后与烯丙基溴进行S H 2'反应,生成良好的1-溴-1,4-二烯收率,并释放出溴自由基。根链。产物二烯的sp 2-碳-溴键通过交叉偶联和羰基化反应进一步官能化。