Tertiary‐Amine Controlled (3+3) or (4+2) Annulations of β′‐Acetoxy Allenoates with N‐Sulfonyl Ketimines: An Entry to m‐Teraryl and Fused Dihydropyridines

Abstract

AbstractLewis base dependent (3+3) and (4+2) annulations of β′‐acetoxy allenoates with N‐sulfonyl ketimines offer m‐teraryl and fused dihydropyridines with varying substituents depending on the tertiary amine as well as subtle changes in the reaction conditions. The triazabicyclodecene (TBD)‐catalyzed (3+3) annulation involves 1,2‐elimination followed by 6‐endo‐dig cyclization as key steps in delivering fused 1,4‐hydropyridines. The same reactants under DMAP catalysis offer m‐teraryl via Mannich coupling, rather than 1,2‐elimination followed by C−N bond cleavage/aromatization. Key intermediates have been identified by HRMS studies.