Copper-Catalyzed Intermolecular Cyclization between Oximes and Alkenes: A Facile Access to Spiropyrrolines

Abstract

A Cu-catalyzed protocol has been developed for the rapid construction of a wide spectrum of structurally interesting spiropyrroline skeletons. This method utilizes readily accessible ketoximes and alkenes as the starting materials and exhibits broad substrate scope and good functional group compatibility. Furthermore, the reaction can be applied for the late-stage modification of bioactive pregnenolone derivatives. The mechanistic investigation suggests that the reactions proceed through a radical process.

Synthesis of Pyrazolo-Fused 4-Azafluorenones in an Ionic Liquid. Mechanistic Insights by Joint Studies Using DFT Analysis and Mass Spectrometry

“…13 C NMR (100 MHz, CD 3 Cl); 112.2 (C), 118.7 (C), 123.7 (CH), 123.8 (CH), 130.4 (CH), 131.8 (C), 134.1(C), 135.9 (CH), 136.6 (CH), 136.7 (CH), 136.8 (CH), 138.1 (CH), 140.1 (C), 142.5 (C), 142.7 (CH), 188.9 (C), 189.3 (C). These spectroscopic data correspond to the previously reported data [63,64].…”

Redox‐Divergent Synthesis of Fluoroalkylated Pyridines and 2‐Pyridones through Cu‐Catalyzed N−O Cleavage of Oxime Acetates

“…Addition of TEMPO to the coupling of 1 a and 2 a did not inhibit the formation of 3 a (conditions A), thus indicating an ionic pathway. In fact, this conclusion is consistent with the formation of product 3 w (Scheme ), since a radical pathway would lead to ring scission . While formation of CF 2 H‐substituted pyridine 4 a was retarded by the addition of TEMPO (conditions B), the reaction was only slightly affected when 1,1‐diphenylethylene was introduced (Scheme a).…”

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 .…”