Copper-Catalyzed Coupling of Oxime Acetates with Isothiocyanates: A Strategy for 2-Aminothiazoles

Abstract

A new strategy for 2-aminothiazoles is developed via the copper-catalyzed coupling of oxime acetates with isothiocyanates. Various 4-substituted and 4,5-disubstituted 2-aminothiazoles were formed smoothly under mild reaction conditions. This process involved copper-catalyzed N-O bond cleavage, activation of vinyl sp(2) C-H bonds, and C-S/C-N bond formations. It is noteworthy that the oxime acetates were used not only as a substrate but also as a single oxidant.

Transition Metal‐Catalyzed Reactions Involving Oximes

“…In 2016, Jiang et al. developed a Cu(I)‐catalyzed oxidative coupling of oxime acetates with isothiocyanates without an external oxidant (Scheme ) . The 2‐aminothiazoles were formed smoothly through N–O bond cleavage, activation of vinyl C sp 2 –H bonds, and C–S/C–N bond formations.…”

Reactivity and Synthetic Applications of α‐Functionalized Oxime Acetates: Divergent Access to Fulleropyrrolidines and Mono‐ and Disubstituted 1‐Fulleropyrrolines via Copper‐Catalyzed Redox‐Neutral N‐Heteroannulation with [60]Fullerene

“…Based on the experimental results and literature precedents, a reasonable mechanism for the formation of products 2 , 4 and 6 was proposed as shown in Scheme . The iminium radical intermediate A is first generated via a single electron transfer (SET) process in the presence of Cu(I) or Cu(II),,,,, and then it quickly isomerizes to delocalized α‐carbon radical species B ,,,, . B then undergoes rapid homolysis of the C–C bond to generate the highly active radical species C (X=N), which could attack C 60 to form fullerenyl radical D .…”

Synthesis of new thiazole and thiazolyl derivatives of medicinal significant-a short review

“…23 In addition, a copper-catalyzed reaction of oxime acetates with isothiocyanates gives various 4-substituted and 4,5-disubstituted 2-aminothiazoles under mild reaction conditions via copper-catalyzed N-O bond splitting, activation of vinyl sp2 C-H bonds, and C-S/C-N bond formations. 24 Copper also, facilitated [3+1+1]-type condensation of oximes, anhydrides and potassiumthiocyanate (KSCN) to give thiazoles in very good yields under very mild reaction conditions. 25,26 The uses of DABCO (1,4-diazabicyclo[2.2.2]octane) as an organocatalyst for synthesis of new thiazole derivatives in short reaction times and good to high yields was also reported.…”