Zirconium-Mediated Synthesis of Arsaalkene Compounds from Arsines and Isocyanides

An atom-economical synthesis of arsaalkenes via a net coupling of aryl arsines with aryl or alkyl isocyanides at zirconium is presented. Reaction of zirconium arsenido complexes (N3N)­ZrAsHAr [N3N = N­(CH2CH2NSiMe3)33–; Ar = Ph, (2) Mes (3)] with aryl and alkyl isocyanides yields arsaalkene products of the general form (N3N)­Zr­[NRC­(H)As­(Ar)]. Two examples (5: R = Mes, Ar = Ph; 6: R = CH2Ph, Ar = Mes) were structurally characterized. Observation of intermediates in the reaction and structural characterization of the previously reported 1,1-insertion product benzylisocyanide with (N3N)­ZrAsPh2 (8), (N3N)­Zr­[η2-C­(PPh2)=NCH2Ph] (9), support the mechanistic hypothesis that these reactions occur via 1,1-insertion followed by rearrangement.