Acyclic Remote 1,5- and 1,4,5-Stereocontrol in the Catalytic Stereoselective Reactions of β‑Lactams with Aldehydes: The Effect of the N‑Methylimidazole Ligand

The application of the N-methylimidazole (N-MI) ligand in the Pd(0)/InI-promoted allylations of aldehydes with β-lactam-derived organoindiums enables the reaction of azetidin-2-ones with diversely substituted allyl moieties, inert under previously reported conditions. As a result, allylations and crotylations of a variety of aromatic and aliphatic aldehydes with previously unavailable chiral ε-amido-allylindiums bearing α-, β-, or γ-substituted allyl fragments were developed. The reactions occur under thermodynamic control with a highly efficient remote 1,5- or 1,4,5-stereocontrol to afford a diversity of (3Z)-2,5-anti-2,6-syn- or (3Z)-2,5-syn-2,6-anti-substituted enediols, aminoalcohols, and homoallylic alcohols in moderate to high yields and with an excellent diastereoselectivity. A detailed study on the effect of the β-lactam and aldehyde structures and chirality on the yield and stereochemistry in the products was carried out.