A novel approach to generate Au-containing all-carbon 1,3-dipoles is developed via an unprecedented migration-fragmentation of ketals/acetals. These in situ generated dipoles undergo rapid [3+2] cycloaddition under mild conditions with various enones/ enals, electron-rich aromatic aldehydes, and N-benzylindole, leading to flexible formation of highly functionalized dihydrofurans and cyclopentenes.