Copper-Catalyzed Twofold Silylmetalation of AlkynesThis work was supported by JSPS KAKENHI Grant Numbers JP15H05641, JP16H04109, JP18H04254, JP18H04409, and JP19H00895. H.Y. thanks The Asahi Glass Foundation for financial support.
Received: 11 May 2019
Accepted after revision: 29 May 2019
25 June 2019 (eFirst)
The first twofold silylmetalation across a C≡C triple bond was achieved. In the presence of a catalytic amount of copper cyanide, diarylacetylenes were converted into 1,2-dimetalated 1,2-disilyl-1,2-diarylethanes on treatment with silylpotassium species generated in situ from disilane and t-BuOK. The dimetalated species were subsequently protonated to yield a series of 1,2-disilyl-1,2-diarylethanes.
References and Notes
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- 10 Even though a free silylpotassium species seems to function in the reaction, the formation of a silicate species generated from disilane and tert-butoxide cannot be excluded.
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- 12 In the presence of smaller amounts of disilane (1.0 equiv) and t-BuOK (1.2 equiv), we obtained recovered alkyne 1a (32%) and disilylated product 3a (19%), as well as the monosilylated alkene (25%), after protic workup. This suggests that a monosilylated copper species is formed just before the the silylpotassium species is consumed. The monosilylated copper species might also add to the alkyne to provide the monosilylated alkene eventually.