Grignard Reagent-Mediated Regioselective 1,8-Addition of α-(2-Thienylidene)-β-ketosulfones

Grignard reagent-mediated and solventcontrolled regioselective 1,8-addition of alpha-(2-thienylidene)-beta-ketosulfones provides diversified substituted 2-thienylmethyl beta-ketosulfones in moderate yields in a diethyl ether-dioxane cosolvent and dioxane (v/v= 4/1) under ice-bath conditions. The 1,4-addition of alpha-heterocyclic beta-ketosulfones was also studied. The structure of the key product was confirmed via X-ray analysis. The uses of various reaction solvents and organomagnesium bromides were investigated for transition metal-free C H functionalization. Related plausible mechanisms are proposed and discussed. The DFT calculations are utilized to rationalize the regioselectivity of the 1,8-addition reaction.

Automated summary

In this study, a diverse range of substituted 2-thienylmethyl beta-ketosulfones were synthesized through a Grignard reagent-mediated and solvent-controlled 1,8-addition reaction. The reaction was conducted in a diethyl ether-dioxane cosolvent and dioxane (v/v=4/1) under ice-bath conditions, resulting in moderate yields. Additionally, the 1,4-addition reaction of alpha-heterocyclic beta-ketosulfones was also investigated, and the structure of the key product was confirmed using X-ray analysis. DFT calculations were employed to rationalize the regioselectivity of the 1,8-addition reaction.