Chemoselective Preparation of Alkynes from Vicinal and Geminal Dibromoalkenes
Hyuga Okumura1, Nurcahyo Iman Prakoso1,2, Tatsuya Morozumi3
1Graduate School of Environmental Science, Hokkaido University, N10W5, Sapporo 060-0810, Japan.
Abstract:
The reductive conversion of vicinal and geminal dibromoalkenes into the corresponding alkynes with iPrMgCl-LiCl (Turbo Grignard reagent) is described. This reaction proceeded in the presence of various functional groups such as ethers, esters, or carbamates under mild conditions in high yields. Due to the selective reactivity, the easily prepared vic-dibromoalkene is considered to be a protecting group of alkyne toward an electrophile. Although butyl lithium has been widely used for the conversion of gem-dibromoalkenes into alkynes in the Corey-Fuchs alkyne synthesis, we report here alternative mild and chemoselective reaction conditions for alkyne synthesis.
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