Iodine‐Triggered Aerobic Oxysulfonylation of Styrenes

Abstract

An iodine-triggered dioxygen activation in oxysulfonylation reactions of unactivated olefins using sulfonyl hydrazides and iodine as catalyst is reported here.I no ne pot,n earq uantitative syntheses of b-hydroxysulfones were achieved at 70 8 8C, within 7h,i na cetonitrile and under aerobic conditions.A plausible mechanism is established by radical trapping and 18 Ol abellinge xperiments for the operation-ally simple,e fficienta nd economically viable transformation. Thed irect activation of aerial oxygen under metal-free and mild conditions is proposed for the oxysulfonylation of olefins.

N‐Iodosuccinimide as Bifunctional Reagent in (E)‐Selective C(sp2)−H Sulfonylation of Styrenes

“…Among these, sulfonyl hydrazide is preferably employed as an excellent synthon due to its high stability, economically viable and easy handling. We have also shown earlier that generation of sulfonyl radicals can be done easily from sulfonyl hydrazide using iodine‐pyridine combination and synthesis of β ‐hydroxysulfones were achieved via aerial dioxygen activation reaction (Scheme a) . However, in this work we are taking similar, but more convenient approach towards synthesis of ( E )‐vinyl sulfones by utilizing the bifunctionality of NIS (Scheme a).…”

“…Furthermore, neither p ‐methyl‐benzenesulfonyliodide 4 a (Scheme b) nor sulfonothioate derivative 5 a (Scheme c) could lead to any sulfonylation product with styrene. Similarly, direct synthesis of vinyl sulfone from the β ‐hydroxysulfone 6 a using NIS and base K 2 CO 3 was also unsuccessful (Scheme d). Therefore, it is rationalized that none of the above mentioned reagents 4 a , 5 a or 6 a could be an intermediate.…”

“…Based on control experiments and literature reports,, a plausible mechanism of the ( E )‐selective sulfonylation of styrene is shown in Scheme . First, NIS underwent homolytic cleavage and abstracted N−H hydrogen sequentially from sulfonyl hydrazide to generate sulfonyl radical IV via I , II and III .…”

“… Sulfone synthesis using sulfonyl hydrazides. a) Iodine‐pyridine catalyzed oxysulfonylation reaction . b) Guoqi Zhang's work using metal co‐catalyst .…”

Copper-catalyzed hydroxyarylsulfonylation of 2-methylpropene using aryldiazonium salts and sulfur dioxide

“…Дещо інший підхід запропоновано у праці [4]. Автори використовують гідразиди арилсульфокислот в реакції з арилалкенами.…”