Chemoselective alkynylation of N-sulfonylamides versus amides and carbamates – Synthesis of tetrahydropyrazines

Abstract

The chemoselective alkynylation of N-sulfonylamides versus amides and carbamates using TMS-EBX as an alkynylating agent leads to the formation of non-symmetrical tetrahydropyrazines from orthogonally protected diamines.

Unconventional Reactivity of Ethynylbenziodoxolone Reagents and Thiols: Scope and Mechanism

“…Ethynylbenziodoxol(on)es (EBXs) [9] have demonstrated their utility as electrophilica lkynylation reagents that readilye ngage ar ange of carbon, [10] sulfur, [11] nitrogen, [12] and phosphorus [13] nucleophiles. Other reactions involving EBX reagents have also been pursued,i ncluding the Pd II -catalyzed transformation of alkynyl benziodoxoles with N-aryl imines and carboxylic acids [14] and copper-catalyzed oxyalkynylation of diazo compounds.…”

Direct Decarboxylative Alkynylation of α,α‐Difluoroarylacetic Acids under Transition Metal‐Free Conditions

“…[9] On the other hand, the reagent ethynylbenziodoxolone (EBX), which is preparedf rom commerciallya vailable 2-iodobenzoic acid andc orresponding alkynylsilane, [10] is as afe and air-stable alkyne source that has found wide applications in decarboxylation,C À H bond activation andm any other types of reactions in recent years. [11][12][13][14] Inspired by these reports,w ee nvisioned as imple and facile construction of the difluoropropargyl moiety under transitionm etal-free conditions by using the above-mentioned a,adifluoroarylacetic acids and ethynylbenziodoxolone (EBX) reagents as difluoromethyl and alkyne source, respectively,w hich would establish an ew synthetic strategyf or difluoropropargyl derivatives (Scheme 1b).…”

Transition‐Metal‐Free Tunable Chemoselective N Functionalization of Indoles with Ynamides

“…To the best of our knowledge, such an intermolecular addition of a nitrogen nucleophile to an ynamide is unprecedented and only two intramolecular examples, first by Urabe and co-workers [10] (in which case a copper assisted process is proposed) and more recently by Aubineau and Cossy, [11] have been reported. A handful of reports describe the addition of indoles and related heterocycles to non- [a] Yields are those of isolated products, unless indicated otherwise.…”