Catalyst dependent mechanistic paths in the reactions of ethyl diazoacetate with β-keto esters

Photocatalytic Reaction of Diazo Compounds with Aldehydes

“…Such cyclopropanes bearing both electron‐donating and electron‐withdrawing groups were found to be easily cleaved 45–49. We have prepared a cyclopropylamine derivative using a reported methodology and subjected it to the developed reaction conditions (Scheme ) 24a…”

“…In this regard, it has been already reported that the reaction of a diazo compound with a carbonyl starting material, depending on the conditions used, follows different pathways 24a–c. In the presence of light diazo compounds furnish carbenes in a singlet ground state via direct photolysis while less reactive triplet carbenes are formed in the presence of triplet‐sensitizers.…”

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

“…Based on the above investigations and the mechanistic studies in the literatures, we speculated the insertion reaction undergoes through a cyclopropanol intermediate 13 , which is formed by a copper‐carbene insertion into the enol of the carbonyl substrates. The intermediate 13 is a typical donor‐accepter cyclopropane and easily proceeded ring‐opening/protonation reactions (Scheme ).…”

“…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.…”

Spirocyclic Amide Acetal Synthesis by [CpRu]‐Catalyzed Condensations of α‐Diazo‐β‐Ketoesters with γ‐Lactams

“…With aldehydes and ketones, but also esters and amides, carbonyl ylides are formed, usually under light irradiation or metal‐catalyzed conditions ( Scheme 1, A ) [8,10–25] . These reactive intermediates condense to form epoxides ( A , path a ), act as 1,3‐dipoles in intra‐ and intermolecular cycloadditions ( A , path b ) or form enol ethers ( A , path c ) [26–30] . Using α‐diazo‐β‐ketoesters as reagents, carbonyl ylides evolve toward the formation of dioxolene adducts instead that are formed by intramolecular condensation ( A , path d ) [31–38] .…”