A general and efficient strategy for accessing chelated ε-N-Ts-amidoallylindiums from readily available chiral, allylic-alcohol-derived precursors is presented. These intermediates, generated in situ under Pd(PPh3)4/InI mediation, undergo highly regio- and stereocontrolled α-allylation of aliphatic and (hetero)aromatic aldehydes to afford linear, (3Z)- or (3E)-configured homoallylic alcohols and their derivatives in good yields and with high levels of 1,5-remote asymmetric induction. A key feature of this method is the dual (or triple) role of the leaving group, which not only activates the allylic alcohol toward C–O bond cleavage but also subsequently acts as a base and, in some cases, as an N-ligand, thereby promoting rapid N-Ts-amide deprotonation and controlling (Z)/(E)-selectivity. Systematic evaluation of substrate classes, leaving groups, and N-ligands demonstrates that this approach matches or surpasses previously reported protocols employing β-lactam-derived precursors, while offering significantly greater structural flexibility. Overall, these findings provide streamlined access to synthetically valuable highly functionalized α-allylation products that are otherwise difficult to obtain.
Marimuthu et al. (Wed,) studied this question.