Divergent Roles of Urea and Phosphoric Acid Derived Catalysts in Reactions of Diazo Compounds

Abstract

Hydrogen-bond-donor catalysts enable a variety of formal insertion reactions of diazo compounds. The role of the catalyst in the reaction system may vary depending on several factors, including the nucleophilicity of the diazo compound and the acidity of the insertion partner. Ureas and phosphoric acid derivatives can offer complementary reactivity patterns when selected as catalysts for selected O-H and S-H insertion reactions of aryl-and diazo-substituted esters.

Catalyst‐ and Light‐free S−H Insertion between Phosphorodithioic Acids and Diazo Compounds: Rapid Access to Dialkylphosphorodithioates

“…The deuterium‐labeling experiment clearly showed the transfer of protons from phosphorodithioic acid to diazo substrate (Scheme 5b). On the basis of these experimental results and previous literatures, [4b,c] a plausible mechanism of this catalyst‐ and light‐free S−H insertion of phosphorodithioic acids with diazo‐compounds is proposed (Scheme 5c). Initially, the diazo compound 1 a undergoes protonation with phosphorodithioic acid 2 a to generate a diazonium cation intermediate, which is subsequently trapped by (EtO) 2 P(S)S − nucleophile to afford the target product 3 aa .…”

“…Based on these dual functional properties, phosphorodithioic acids have been used in the direct conversion with several electrophiles, such as olefin, [9] chalcone, [10] epoxide, [11] vinyl cyclopropane [12] and vinyl oxetane [13] . Inspired by these applications and by the Brønsted acid promoted S−H insertion reactions, [4b,c] we envisaged a catalyst‐ and light‐free S−H insertion of phosphorodithioic acids with diazo compounds (Scheme 1c), which may provide a cost‐effective strategy for the construction of C−S bonds and allow access to those marketed phosphorodithioate pesticides or candidate agrochemicals (Scheme 1d) [14] and other interesting molecules with ease. To the best of our knowledge, such direct assembly of phosphorodithioic acids with diazo compounds has not been disclosed yet.…”

A New Approach to the S–H Insertion Reaction of α-Keto Esters and Thiols

“…4 To date, various strategies have emerged to realize this reaction. For example, transition-metal catalysis, 5 organocatalysis, 6 heterogeneous catalysis, 7 biocatalysis, 8 and photocatalysis 9 have proven useful in the context of this reaction (Scheme 1). Although they represent significant achievements, these procedures typically not only require elaborately selected catalysts but also diazo compounds.…”