Stereoselective Nickel‐Catalyzed Cycloisomerization of 1,6‐Dienes

Highly stereoselective cycloisomerization of 1,6‐dienes with a catalyst system based on [Ni(allyl)(cod)][BARF] and Wilke’s azaphospholene all‐(R)‐1 is described. Unprecedented high enantiomeric excesses of up to 91% were obtained for the formation of five‐membered cyclic products from symmetrically substituted 1,6‐dienes. High chemo‐ and regioselectivities were achieved also for unsymmetrically 1,6‐dienes substituted in terminal position leading again to five‐membered cyclic products in fair to very good yields. Cycloisomerization products were subjected to sequential hydroboration as well as hydrogenation of the exo‐methylene functional group. Promising diastereoselectivities were achieved and these reaction sequences could be efficiently performed in a one‐pot procedure.