Production of Formamides from CO and Amines Induced by Porphyrin Rhodium(II) Metalloradical.

It is of fundamental importance to transform carbon monoxide (CO) to petrochemical feedstocks and fine chemicals. Many strategies built on the activation of C≡O bond by π-back bonding from the transition metal center were developed during the past decades. Herein, a new CO activation method, in which the CO was converted to the active acyl-like metalloradical, [(por)Rh(CO)]• (por = porphyrin), was reported. The reactivity of [(por)Rh(CO)]• and other rhodium porphyrin compounds, such as (por)RhCHO and (por)RhC(O)NH nPr, and corresponding mechanism studies were conducted experimentally and computationally and inspired the design of a new conversion system featuring 100% atom economy that promotes carbonylation of amines to formamides using porphyrin rhodium(II) metalloradical. Following this radical based pathway, the carbonylations of a series of primary and secondary aliphatic amines were examined, and turnover numbers up to 224 were obtained.