Carbanion induced synthesis of annulated unsymmetrical biaryls through ring transformation of 2H-pyran-2-one

Abstract

An innovative and convenient one-pot synthesis of unsymmetrical macrocyclic biaryls (3, 5 and 8), dibenzo[a,c]cycloheptenes (10), 3,4-dihydro-2(1H)-naphthones (15), tetrahydroisoquinolines (18), dihydro-1H-isothiochromenes (20), benzo[c]thiochromenes (22) and 2,3-dihydro-1-benzothiophenes (24) is described. These compounds are obtained through base-catalyzed ring transformation reactions of suitably functionalized 2H-pyran-2-ones (1,6) by a carbanion, generated from cycloalkanone (2,4,7), benzosuberone (9), cyclohexanedione monoketal (12), 4-piperidone (17), tetrahydrothiopyran-4-one (19), thiochroman-4-one (21) or tetrahydrothiophene-3-one (23).