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Reactions of an Isolable Dialkylstannylene with Propynoates and Benzyne

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journal contribution
posted on 30.07.2018, 19:48 by Jian Xu, Xu-Qiong Xiao, Chenting Yan, Zhifang Li, Qiong Lu, Qian Yang, Guoqiao Lai, Mitsuo Kira
The reactions of stable monomeric dialkylstannylene 1 with methyl and ethyl propynoates give the corresponding 1:2 adducts, alkenyl­(alkynyl)­stannane 2 and 3 in high yields, while 1 does not react with parent acetylene or common mono- and disubstituted acetylenes such as phenylacetylene, trimethylsilylacetylene, diethyl 2-butynedioate, etc. Notably, 2 and 3 have the Z-configuration of the alkenyl moieties, in contrast to similar adducts obtained by the known reactions of silylenes with terminal acetylenes. It is suggested that the formation of a carbonyl oxygen-coordinate cyclic zwitterion as a key intermediate is essential for the reactions. Stannylene 1 adds to in situ generated benzyne, forming a 1:1 adduct having a unique 3-stanna-1-silaindane ring system.