Rhodium(II)-catalyzed multicomponent assembly of α,α,α-trisubstituted esters via formal insertion of O–C(sp3)–C(sp2) into C–C bonds

Abstract The direct cleavage of C(CO)−C single bonds, delivering otherwise inaccessible compounds, is a significant challenge. Although the transition metal-catalyzed insertion of functional groups into C(CO)−C bonds has been studied, strained ketone substrates or chelating assistance were commonly required. In this article, we describe a rhodium(II)-catalyzed three-component reaction of 1,3-diones, diazoesters, and N,N -dimethylformamide (DMF), leading to an unusual formal insertion of O–C(sp 3 )–C(sp 2 ) into unstrained C(CO)−C bonds. This procedure provides a rapid entry to a gamut of otherwise inaccessible α,α,α-trisubstituted esters/amide from relatively simple substrates in a straightforward manner. 55 examples of highly decorated products demonstrate the broad functional group tolerance and substrate scope. The combination of control experiments and isotope-labeling reactions support that O, C(sp 3 ), and C(sp 2 ) units derive from 1,3-diones, diazoesters, and DMF, respectively.