Fig. 4: Hypothetical Models for chiral insertion and regioselective insertion.

a Chiral NHC–Ni(II)H insertion to diene which give major enantiomer 3. b, c Unfavorable steric interactions among NHC and diene which disfavored the insertion. d Steric control regioselective insertion of terminal olefin. e Role of heteroatom in regioselective insertion of homoallylether.