A new method was developed to synthesize polyfunctionalized dihydrofuran and tetrahydrofuran derivatives from the three-component [2 + 2 + 1] cycloaddition of the diazoesters with aryl/alkenyl aldehydes and alkyne/olefin dipolarophiles by using a Ag(I) N-heterocyclic carbene complex as the catalyst. A carbonyl ylide intermediate was generated, which undertook an endo-type 1,3-dipolar cycloaddition to provide the desired dihydro-/tetrahydrofurans in high regio- and diastereoselectivities by using α-aryl or α-alkenyl diazoesters.