A mild and environmentally friendly construction of thieno-fused lactam scaffolds has been successfully developed through NHC-catalyzed 3 + 3 annulation of bromoenals and thiophen-3-amines. A diverse range of thieno3,2-bpyridinones were efficiently synthesized in moderate-to-excellent yields with good-to-excellent enantioselectivities. Notably, protecting-group-free thiophen-3-amines were compatible with this strategy in the presence of the green solvent 2-MeTHF.
Shi et al. (Fri,) studied this question.