Polyfunctionalization of vicinal carbon centers and synthesis of unsymmetric 1,2,3,4-tetracarbonyl compounds

Abstract

The synthesis and characterization of organic compounds with unusual atom or functional group connectivity is one of the main driving forces in the discovery of new synthetic methods that has raised the interest of chemists for many years. Polycarbonyl compounds are such compounds wherein multiple carbonyl groups are directly juxtaposed and influence each other’s chemical reactivity. While 1,2-dicarbonyl or 1,2,3-tricarbonyl compounds are well-known in organic chemistry, the 1,2,3,4-tetracarbonyl motif remains barely explored. Herein, we report on the synthesis of such 1,2,3,4-tetracarbonyl compounds employing a synthetic strategy that involves C-nitrosation of enoldiazoacetates, while the diazo functional group remains untouched. This strategy not only leverages the synthesis of 1,2,3,4-tetracarbonyl compounds to an unprecedented level, it also accomplishes the synthesis of 1,2,3,4-tetracarbonyl compounds, wherein each carbonyl group is orthogonally masked. Combined experimental and theoretical studies provide an understanding of the reaction mechanism and rationalize the formation of such 1,2,3,4-tetracarbonyl compounds.

A Carbene Relay Strategy for Cascade Insertion Reactions

“…The high electrophilicity of heteroatom‐substituted metal carbenes was further explored, leading to the discovery of a Ritter‐type double amidation reaction. The Ritter reaction is known for its quick and efficient synthesis of sterically congested amides, which are prevalent in functional molecules [57–60] . Typically, a strong acid is needed to generate a highly reactive carbocation intermediate.…”

“…The Ritter reaction is known for its quick and efficient synthesis of sterically congested amides, which are prevalent in functional molecules. [57][58][59][60] Typically, a strong acid is needed to generate a highly reactive carbocation intermediate. It was hypothesized that a weak nucleophile, such as a nitrile, could add to the transient S + -substituted metal carbene.…”