Enantioselective Nickel‐Catalyzed Hydrocyanation of Homostilbenes.

We investigated the previously unknown enantioselective Ni‐catalyzed hydrocyanation of 1,3‐diarylpropenes (homostilbenes). For this purpose, a series of (E)‐homostilbenes were prepared by (microwave‐assisted) Pd‐catalyzed coupling of allylic alcohols with aryl‐boronic acids. Employing our established catalyst system formed from Ni(cod)2 and a TADDOL‐derived chiral phosphine‐phosphite ligand and using TMSCN as an in situ source of HCN, the hydrocyanation of various homostilbenes was studied. The synthetic usefulness of the methodology was demonstrated in a short synthesis of the new (allo‐) colchicine analogue 7‐cyano‐11‐methoxy‐colchinol involving an PIDA‐mediated oxidative cyclization of the corresponding hydrocyanation product to set up the 7‐membered ring. The absolute configuration of 2,4‐diphenylbutyronitrile was assigned by comparison of experimental and calculated ECD spectra. [ABSTRACT FROM AUTHOR]