Copper-catalyzed formylation of alkenyl C–H bonds using BrCHCl₂ as a stoichiometric formylating reagent

Abstract

The first example of copper-catalyzed formylation of alkenyl C–H bonds with BrCHCl2 as a stoichiometric formylating reagent for the facile synthesis of α,β-unsaturated aldehydes has been developed.

Recent Developments in the Polychloroalkylation by Use of Simple Alkyl Chlorides

“…The three‐component difunctionalization of olefins is a powerful tool for the synthesis of complex molecules, and could rapidly assembled new functional groups and frameworks from readily available starting materials [25] . Intermolecular polychlorination of alkene is a powerful strategy for the synthesis of complex polychlorinated hydrocarbons, while building C−C bonds and other new chemical bonds, such as C−N, C−O, etc [26–31] . Recent studies have shown that polychlorination of olefins is often achieved by carbon‐halogen bond cleavage and carbon‐hydrogen bond cleavage, and could be effectively used to increase molecular complexity.…”

“…1,2‐oxyalkylation, then dehydration one‐pot method to synthesize α , β ‐unsaturated aldehydes in the presence of 1‐propanephosphonic acid cyclic anhydride (T3P) in EtOAc at 100 °C (Scheme 31). [30] Estrone derivative can also be converted into corresponding aldehyde.…”

“…Alkyl chloride units, especially polychlorinated hydrocarbons, are a very important class of functional groups, which are widely found in bioactive molecules such as pharmaceuticals and pesticides [1] . Simultaneously, polychlorinated hydrocarbons units also can further transformed into a variety of new compounds, including aldehyde, [2a–d] ester, [2e–h] ketone, [2i–n] carboxylic acid, [2o–r] alkene, [2s–t] carbene, [2u–x] etc [2y–z] . Therefore, the formation of polychlorinated alkane units have been well established over the past few decades.…”

“…Recently, with the development of radical chemistry, simple alkyl chlorides (such as dichloromethane, chloroform etc.) have been used as effective precursors to introduce the polychlorinated groups through the coupling with alkanes, [4–7] addition of olefins [9–26] and cyclizations [27–36] . Among them, due to the high reactivity of polychlorinated radical intermediates, the radical‐mediated polychloroalkylation groups have been considered to be an indispensable tool for the synthesis of complex polychlorinated compounds.…”

Copper-Catalyzed Dichloromethylazidation of Alkenes Using BrCCl2H as a Stoichiometric Dichloromethylating Reagent

“…To address the issue of environment-unfriendliness due to the requirement of CHCl 3 or CH 2 Cl 2 used as the solvent, we have recently developed a copper-catalyzed formylation of alkenyl C–H bonds, using BrCCl 2 H as a stoichiometric formylating reagent . Mechanistic studies revealed that an in-situ-generated dichloromethyl radical ( · CCl 2 H) was captured by styrene and quenched by H 2 O, followed by dehydration to afford the final product (eq 3 in Scheme ).…”