Transfer Hydrocyanation of α‐ and α,β‐Substituted Styrenes Catalyzed by Boron Lewis Acids

A straightforward gram‐scale preparation of cyclohexa‐1,4‐diene‐based hydrogen cyanide (HCN) surrogates is reported. These are bench‐stable but formally release HCN and rearomatize when treated with Lewis acids. For BCl3, the formation the isocyanide adduct [(CN)BCl3]‐ and the corresponding Wheland complex was verified by mass spectrometry. In the presence of 1,1‐di‐ and trisubstituted alkenes, transfer of HCN from the surrogate onto the C‐C double bond occurs, affording highly substituted nitriles with Markovnikov selectivity. The success of the transfer hydrocyanation depends on the Lewis acid employed; catalytic amounts of BCl3 and (C6F5)2BCl are shown to be effective while B(C6F5)3 and BF3∙OEt2 are not.

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