Iodine‐Mediated Coupling of Cyclic Amines with Sulfonyl Hydrazides: an Efficient Synthesis of Vinyl Sulfone Derivatives

Abstract

An efficient iodine-mediated coupling of cyclic amines with sulfonyl hydrazides is reported. This transformation opens a new route to the synthesis of vinyl sulfones derivatives, which is a common structural motif in natural products and pharmaceuticals. Tentative mechanistic studies suggest that this reaction is likely to involve a radical process.

Transition‐Metal‐Free Methods for the Remote C−H Bond Functionalization of Cyclic Amines

“…Gu, Xia and co‐workers later reported another β ‐sulfonylation reaction between tertiary cyclic amines and sulfonyl hydrazides, using I 2 and t ‐butyl hydrogen peroxide (TBHP) as the oxidants (Scheme 11). [31] A control experiment with radical scavenger TEMPO under otherwise identical conditions gives dramatically diminished yield of the desired product. The authors hence proposed a radical‐based mechanism where TBHP is reduced to hydroxide and t ‐butoxy radical by iodide.…”

Advances in Vinyl Sulfone Catalyzed Synthesis: Methods, Mechanisms and Perspectives

“…Recently, Rong and co‐workers reported that molecular iodine can replace transition metals to mediate the coupling reaction for the synthesis of vinyl sulfones (Scheme 9). [59] The first use of sulfonyl hydrazide for the sulfonylation reaction of cyclic amines was proposed. Using 1,4‐dioxane as a solvent, together with TBHP and NaHCO 3 , the chemically stable sulfonyl hydrazide generated in situ was coupled with cyclic amines under mild conditions for the efficient synthesis of vinyl sulfones in 95 % yield, catalyzed by iodine.…”

“…Molecular iodine mediated synthesis of vinyl sulfone from sulfonyl hydrazide and cyclic amine. [59] thermally decomposed into sulfonyl radicals. Finally, two different pathways are used to combine with alkynes and molecular iodine to form (E)-β-iodovinyl sulfones.…”

Visible-light-induced dehydrogenative sulfonylation of tertiary amines under transition-metal- and photocatalyst-free conditions

“…9 Very recently, Xia et al developed a coupling of cyclic amines with sulfonyl hydrazides under similar reaction conditions. 10 In the works carried out by Willis and Talbot et al , N -iodosuccinimide (NIS) was employed as the oxidant in this transformation. 11 Fan's group used the in situ generated SO 2 combined with dicumyl peroxide to achieve a FeCl 3 -catalyzed cascade reaction for the synthesis of β-methylsulfonylated N-heterocycles.…”