Synthesis of hydrohalocyclobutenes through dechlorination of hydrohalocyclobutanes in amide solvents

In this study, we synthesized hydrohalocyclobutenes through the dechlorination of hydrohalocyclobutanes in N,N -dimethylformamide and N,N -dimethylacetamide. The structure of the reaction site −CClR 1 −CClR 2 – (R 1 = H, F; R 2 = H, F, Cl) of the reactants was critical for the efficient reductive dechlorination from the 1- and 2- positions. The reaction proceeded efficiently at the –CFCl–CFCl–, –CFCl−CCl 2 –, and −CHCl−CHCl– groups. Conversely, the –CFCl−CHCl– group could hardly afford the dechlorinated product. Based on these results, we propose a rational reaction mechanism. • Amide solvent is rarely reported as a dechlorination reagent. • No metal catalyst was applied so that this approach was facile and mild. • Dechlorination proceeded efficiently at the –CFCl–CFCl–, –CFCl−CCl 2 –, and −CHCl−CHCl– groups located in the molecular structure of reactants. • The –CFCl−CHCl– group located in the molecular structure of reactants could hardly afford the dechlorinated product. • A series of hydrohalocyclobutenes were prepared with high selectivity. In this study, we synthesized hydrohalocyclobutenes through the dechlorination of hydrohalocyclobutanes in N,N -dimethylformamide and N,N -dimethylacetamide. The structure of the reaction site −CClR 1 −CClR 2 – (R 1 = H, F; R 2 = H, F, Cl) of the reactants was critical for the efficient reductive dechlorination from the 1- and 2- positions. The reaction proceeded efficiently at the –CFCl–CFCl–, –CFCl−CCl 2 –, and −CHCl−CHCl– groups. Conversely, the –CFCl−CHCl– group could hardly afford the dechlorinated product. Based on these results, we propose a rational reaction mechanism.