With the relay process of Ag(I)/Au(I)
catalysts, a one-pot synthesis
of skeletally rearranged (1-hydroxymethylidene)indene derivatives
from 2-alkynylbenzaldehydes and α-diazo esters is described.
This cascade sequence involves Au(I)-catalyzed 5-endo-dig attack of highly enolizable aldehydes at the tethered alkynes, leading
to carbocyclizations with a formal 1,3-hydroxymethylidene transfer.
On the basis of density functional theory calculations, the mechanism
likely involves formation of cyclopropylgold carbenes, followed by
an appealing 1,2-cyclopropane migration.