Copper-mediated oxidative [3 + 2]-annulation of nitroalkenes and pyridinium ylides: general access to functionalized indolizines and efficient synthesis of 1-fluoroindolizines

Abstract

Novel 1-fluoroindolizines were obtained via copper(ii)-mediated oxidative [3 + 2]-annulation of in situ generated pyridinium ylides and fluoronitroalkenes.

[3 + 2]-Annulation of gem-Difluoroalkenes and Pyridinium Ylides: Access to Functionalized 2-Fluoroindolizines

“…Flash column chromatography was performed with silica gel (particle size 0.04−0.05 mm). 1 H NMR 13 C NMR, and 19 F NMR spectroscopic data were recorded using Bruker AMX-400 instrument and calibrated by using the residual solvent peaks as an internal reference (CDCl 3 [ 1 H: 7.26, 13 C: 77.16]; DMSO [ 1 H: 2.5, 13 C: 39.52] and external CCl 3 F, respectively. Coupling constants (J) are given in hertz.…”

Oxidative [3+2] Annulation of Pyridinium Salts with gem‐Difluoroalkenes: Synthesis of 2‐Fluoroindolizines

“…Construction of the heterocycles with fluorine‐containing synthetic blocks provides an alternative strategy of the synthesis of fluorinated heterocycles. For example, Tabolin and co‐workers reported a copper‐mediated oxidative [3+2] annulation of α‐fluoronitroalkenes with pyridinium ylides for the synthesis of 1‐fluoroindolizines (Scheme 1b) [7d] . For the synthesis of 2‐fluoroindolizines, Chen and co‐worker reported a [3+2] cycloaddition of fluoroalkenes with pyridinium ylides for the synthesis of 2‐fluoroindolizines [7b] .…”

Diels–Alder reaction of β-fluoro-β-nitrostyrenes with cyclic dienes

“…This process takes place with simultaneous elimination of bromine, and gives the target structures solely in the Z-isomeric form in high yields (up to 92%). These fluorinecontaining olefins activated by a nitro group proved to be the appealing building blocks for the construction of numerous monofluorinated compounds [51][52][53][54][55][56]. This paper is devoted to a new synthetic approach to novel monofluorinated bicyclic compounds, namely norbornenes and bicyclo[2.2.2]oct-2-enes and their subsequent functionalization.…”