摘要
We report gold catalyzed [4+3]-annulations between benzopyriliums and 3-alkyl-2-diazo-3-vinyl carbonyls, yielding 7H-benzo[7]annulene products efficiently. Notably, the carbon skeletons of resulting 7H-benzo[7]annulenes are structurally rearranged, accompanied by migrations of their alkyl and ketone motifs. Apart from applicable substrates over a wide scope, these annulatios are applicable to pyriliums and 3-alkyl-2-diazo-3-vinyl esters to increase their reaction significance. We postulate a mechanism involving an initial [4+2]-cycloaddition between benzopyriliums and 3-alkyl-2-diazo-3-vinyl carbonyl species, followed by formation of gold carbenes to induce a ring expansion and group migrations.