Catalyst‐Dependent Chemoselective Formal Insertion of Diazo Compounds into C−C or C−H Bonds of 1,3‐Dicarbonyl Compounds

Abstract

A catalyst-dependent chemoselective one-carbon insertion of diazo compounds into the C-C or C-H bonds of 1,3-dicarbonyl species is reported. In the presence of silver(I) triflate, diazo insertion into the C(=O)-C bond of the 1,3-dicarbonyl substrate leads to a 1,4-dicarbonyl product containing an all-carbon α-quaternary center. This reaction constitutes the first example of an insertion of diazo-derived carbenoids into acyclic C-C bonds. When instead scandium(III) triflate was applied as the catalyst, the reaction pathway switched to formal C-H insertion, affording 2-alkylated 1,3-dicarbonyl products. Different reaction pathways are proposed to account for this powerful catalyst-dependent chemoselectivity.

Gold‐Catalyzed Formal C−C Bond Insertion Reaction of 2‐Aryl‐2‐diazoesters with 1,3‐Diketones

“…The aryl ester moiety of the diazoesters plays a key role in the unusual chemoselectivity, and the addition of a Brønsted acid to the reaction mixture improves the yield of the C−C bond insertion product. While we were preparing this manuscript, Bi and co‐workers reported an elegant AgOTf‐catalyzed C−C bond insertion reaction of 2‐aryl‐2‐diazoacetates with aryl 1,3‐diketones 2 (where R 1 or R 2 is an aryl group). Compared with this silver‐catalyzed system, our gold‐catalyzed system exhibits higher activity (reaction time: 1 h for gold versus 6 h for silver; catalyst loading: as low as 0.5 mol % for gold versus 10 mol % for silver) and can be extended to alkyl 1,3‐diketones (where R 1 , R 2 , or both are alkyl).…”

“…More importantly, we found that even aliphatic 1,3‐diketones underwent C−C bond insertion reactions with good yields ( 3 aq – 3 as , 70–79 % yield). It is worth noting that the AgOTf‐catalyzed reaction of methyl 2‐diazo‐2‐phenylacetate with a typical aliphatic 1,3‐diketone ( 2 q ) under the optimal conditions described by Bi and co‐workers gave a poor yield (18 %) of the C−C insertion product. The structure of 3 ab was confirmed by means of single‐crystal X‐ray analysis…”

Synthetic Exploration of α‐Diazo γ‐Butyrolactams

“…α‐Diazo monocarbonyl compounds have attracted considerable attention due to their high reactivity and wealth of possible synthetic transformations . Today, however, certain such compounds remain poorly explored.…”

Cu/PCy3‐Catalyzed Formal Carbene Insertion into Electron‐Deficient C−H Bonds

“…The intermolecular carbene insertion into the electron‐deficient C−H bonds is more challenging, and the chemoselectivity of reaction using copper or dirhodium catalysts is poor . Quite recently, several gold catalysts, copper catalysts, scandium catalysts, diene‐Rh(I) catalysts were developed for the intermolecular carbene insertion into the C−H bonds of 1,3‐diketones, cyclic lactones and β‐ketoesters. The known catalysts for carbene insertion into electron‐deficient C−H bonds are highly substrate dependent.…”