Divergent Reactions between Alkynes and Dibenzenesulfonimide: Selective Synthesis of Ynamides and Enamides under Metal‐Free Conditions

Abstract

Divergent reactions between alkynes and dibenzenesulfonimide that can generate ynamides and enamides selectively are reported. Oxidative C(sp)À H bond amidation of various arylacetylenes occurred in the presence of a hypervalent iodine reagent to form the corresponding ynamides.Without any catalyst or oxidant, direct hydroamidation occurred to produce regioselective Markovnikov's enamides. Both reactions proceeded under facile, neutral, and metalfree conditions and possessed the merit of stable performance and easy operation.

Cross‐Dehydrogenative Alkynylation: A Powerful Tool for the Synthesis of Internal Alkynes

“…Two years later, Arvidsson and co‐workers also described a similar reaction . For the special dibenzenesulfonimide, the CDC reaction with terminal aromatic alkynes could be realized under the metal‐free reaction conditions using PhI(OAc) 2 as an oxidant …”

Updates on hypervalent-iodine reagents: metal-free functionalisation of alkenes, alkynes and heterocycles

“…The regioselective Markovnikov enamides were synthesized without catalysts and oxidants. 80 In 2019, the Majee group disclosed an efficient approach for the synthesis of α-sulfonylamino ketones (46) from terminal alkynes (45) and sulfonamides using PIDA. The methodology features commercially available reactants, ease of product isolation/purification, and metal-free and environmentally benign reaction conditions (Scheme 27).…”

Hypervalent Iodine Reagent‐Mediated Selective Vinyl C−H Amidation of 4‐Alkoxystyrenes with Diarylsulfonimides for Preparation of Enamides

“…Significant achievements have also been made in selective C−H bond functionalization promoted by hypervalent iodine reagents . Recently we have found divergent reactivities between alkynes and dibenzenesulfonimide with or without hypervalent iodine reagents (Scheme d) . Ynamides were formed through alkynyl C−H amidation in the presence of a hypervalent iodine reagent.…”

“…[8] Recently we have found divergent reactivities between alkynes and dibenzenesulfonimide with or without hypervalent iodine reagents (Scheme 1d). [9] Ynamides were formed through alkynyl CÀ H amidation in the presence of a hypervalent iodine reagent. Hydroamidation occurred without any oxidant to produce the corresponding enamides whose regioselectivity followed the Markovnikov's rule.…”