Au(I) and HOTf-Catalyzed Cascade [5+1]-Annulations between Allenylacetals and Diazo Esters To Form 1,3-and 2,3-Disubstituted Naphthoates, Respectively

Gold-catalyzed [5+1]-annulations between allenylacetals with diazo esters to form 1,3-disubstituted naphthoate derivatives are described. Notably, this reaction chemoselectivity is switched to 2,3-naphthoate products when using the HOTf catalyst. Mechanistic studies of these reactions support an acetal activation, in which oxoniums are formed initially, followed by attack of the allene, generating allyl cations to trap alpha-diazo esters. In gold catalysis, such diazo addition intermediates undergo Roskamp rearrangement, whereas in HOTf catalysis the same intermediates undergo a Conia-ene reaction instead. image