Rhodium(II)-catalyzed multicomponent assembly of α,α,α-trisubstituted esters via formal insertion of O-C(sp<sup>3</sup>)-C(sp<sup>2</sup>) into C-C bonds.

Ba, Dan; Wen, Si; Tian, Qingyu; Chen, Yanhui; Lv, Weiwei; Cheng, Guolin · Nat Commun · 2020

basic_science · Level V

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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<sup>3</sup>)-C(sp<sup>2</sup>) 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<sup>3</sup>), and C(sp<sup>2</sup>) units derive from 1,3-diones, diazoesters, and DMF, respectively.