Functionalization of Diazo Groups by the Nucleophilic Addition of Two Molecules of a Dimethylsulfonium Ylide to α-Diazo-β-ketoesters/ketones: Synthesis of Highly Functionalized Hydrazones

Abstract

The intrinsic electrophilic feature for the terminal nitrogen of α-diazo-β-ketoesters/ketones has been elucidated by the intermolecular nucleophilic addition of two molecules of a dimethylsulfonium ylide. This methodology allows for access to highly functionalized hydrazones with a broad scope and good functional group tolerance. The reaction operates under simple and mild conditions without using a catalyst.

Metal-Free Chemoselective Reaction of Sulfoxonium Ylides and Thiosulfonates: Diverse Synthesis of 1,4-Diketones, Aryl Sulfursulfoxonium Ylides, and β-Keto Thiosulfones Derivatives

“…In recent years, the use of sulfoxonium ylides as the C1 or C2 synthons under the catalysis of transition metals (such as rhodium, ruthenium, cobalt, palladium, iridium, and other metals) has successfully achieved the activation of sp 2 C–H bonds of aryl groups and the synthesis of various heterocyclic compounds such as furan, indole, quinoline, pyrrole, and pyrimidine . In 2019, Xu’s group reported the reaction of sulfoxonium ylides with diazo compounds to prepare highly functionalized hydrazone compounds (Figure , eq 1) . We made a preliminary attempt to react thiosulfonates with sulfoxonium ylides.…”

“…Based on the above experimental results and previous reports, , we propose a plausible mechanism in Scheme . First, homolysis of 2a gives sulfone radical I and a phenylthio radical.…”

Base Promoted Three-Component Annulation of 4-Diazoisochroman-3-imines with Dimethylsulfonium Ylides: Synthesis of Highly Functionalized Isochromeno[4,3-c]pyridazines

“…17 Recently, Xu's group reported a direct functionalization of the terminal nitrogen atom of α-diazo-β-ketoesters/ketones by utilizing dimethylsulfonium ylides as nucleophiles under catalyst-free conditions (Scheme 1A). 18 This functionalization proceeds via the formation of zwitterionic intermediates, which are quite stable as compared to their azo-counterparts. 19 We have been working on the chemistry of three different classes of stable cyclic diazo compounds, e.g., 3-diazoindolin-2imines, 20a,b 4-diazoisochroman-3-imines, 20c and 4-diazoisoquinolin-3-ones, 20d developed in our group.…”

Gold-Catalyzed Synthesis of Diaza-hexatrienes Via Diazo Attack at Vinylgold Carbenes: An Easy Access to 1H-Pyrazolo[4,3-b]pyridine-5-ones

“…Scheme shows the stepwise functionalization of our resulting 2,3-diaza-1,3,5-hexatriene products; these acyclic heterotrienes are not well-explored with their chemical functionalizations, but their preparations have been reported . For one representative 4f , its ester can be hydrolyzed to form acid 9 with p -toluenesulfonic acid (PTSA) in wet toluene.…”