Study On The Iodine Catalyzed Sulfonylation Of Quinolines N-Oxides

The aromatic sulfone skeleton is an important scaffolds for the synthesis of natural products and drugs. The conventional methods have typically involved a nucleophilice substitution reaction of halide with thiol, followed by oxidation of the corresponding sulfides. Sulfonylation of the aromatic compound based on the transition-metal-catalyzed C-H bond activation has become a facile and robust tool. However, there are some challenges with these procedures, such as requirement of novel metal, prefunctionalized starting materials and foul-smelling and volatile sulfur sources such as thiols and thiolates. Hence, the exploration of new, green, and practical methods, especially metal-free pathways, to access C-S bond formation using stable and environmentally friendly reagents is still highly desired.We developed an I2-catalysed direct sulfonylation of quinolines N-oxides with sulfonyl hydrazides in the presence of sodium acetate(Scheme 1). This method features with a simple system, high efficiency, environmental friendliness, and metal-free conditions. Aliphatic and aryl sulfonyl hydrazides smoothly undergo sulfonylation with quinolines N-oxides in good yields. A tentative mechanism is proposed on the basis of the previous reports and the controlled experiment results in Scheme 2.