Cyanoformate esters add across 1,2-dienes in the presence of a nickel/PMe(2)Ph catalyst to afford beta-cyano-alpha-methylenealkanoates regioselectively, which are kinetically favored and readily isomerize to thermodynamically favored alpha-cyanomethyl-alpha,beta-unsaturated carboxylates at high temperature under the nickel catalysis, possibly through oxidative addition of the C-CN bond. Similar cyanoesterification products are produced from chloroformate esters, trimethylsilyl cyanide, and 1,2-dienes in the presence of a nickel/dppp catalyst. The resulting cyanoesterification products have a structure of allylic cyanide and thus undergo further allyl cyanation reaction across alkynes with the aid of a nickel/P(4-CF(3)-C(6)H(4))(3) catalyst to afford highly substituted acrylonitrile derivatives.
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http://dx.doi.org/10.1021/ja9010282 | DOI Listing |
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