Isocyanide‐Induced Activation of Copper Sulfate: Direct Access to Functionalized Heteroarene Sulfonic Esters

Abstract

A novel and direct approach to alkyl/aryl heteroarene sulfonic esters using copper sulfate as the environmentally benign inorganic sulfonation reagent was first realized with the aid of isocyanide. A variety of heterocycles reacted to afford the corresponding sulfonic esters through C-H functionalization. In this transformation, the otherwise inert copper sulfate was unusually activated by an isocyanide and employed as the source of the sulfonic substituents in an unprecedented fashion. The findings suggest that an appropriate activator may liberate the chemical activities of some relatively inert inorganic salts for organic synthesis.

Atom Efficient Magnesiation of N‐Substituted Alkyl Indoles with a Mixed Sodium‐Magnesium Base

“…N ‐methylindole was purchased from Aldrich and stored over 4 Å molecular sieves. N ‐ethylindole, N ‐isopropylindole, n BuNa, and Mg(CH 2 SiMe 3 ) 2 were prepared according to literature procedures.…”

From Alkenes to Isoxazolines via Copper-Mediated Alkene Cleavage and Dipolar Cycloaddition

“…Almost at the same time, Shi and co-workers developed a ortho C–H chlorination in the presence of CuCl 2 . Isocyanide induced activation of copper sulfate is recently disclosed by our group, affording sulfonic esters through C–H sulfonation . Besides, copper nitrate has been proven to be a common and versatile reagent for the synthesis of nitro compounds, nitrates, and heterocycles …”

“…8 Isocyanide induced activation of copper sulfate is recently disclosed by our group, affording sulfonic esters through C−H sulfonation. 9 Besides, copper nitrate has been proven to be a common and versatile reagent 10 for the synthesis of nitro compounds, 11 nitrates, 12 and heterocycles. 13 Transition-metal-promoted alkene cleavage is a fundamental functional group interconversion in olefin chemistry, and takes a privileged position in the synthesis of a wide variety of natural products, pharmaceuticals, and functional materials.…”

Radical-mediated vicinal addition of alkoxysulfonyl/fluorosulfonyl and trifluoromethyl groups to aryl alkyl alkynes

“… 5 Consequently, these methods are not compatible with sensitive functional groups and often suffer from tedious purification procedures or limited sources of the organosulfur starting materials. Recent methods for introduction of a sulfonate moiety focus on arylsulfonates, 6 while the diversity-oriented synthesis of alkenylsulfonate esters by Wittig reactions is limited by the strongly basic conditions employed. 1 d ,7 Alkenylsulfonyl fluorides are of special interest due to the electrophilic character of both the sulfur center and the β-carbon, representing a unique warhead for covalent binders.…”