Redox-Neutral and Atom-Economic Route to β-Carbolines via Gold-Catalyzed [4 + 2] Cycloaddition of Indolylynamides and Cyanamides

Abstract

Gold­(I)-catalyzed [4 + 2] cycloaddition of indolylynamides and cyanamides (aminonitriles) is an efficient redox-neutral and atom-economic route to diversely substituted 1,3-diamino-β-carbolines. The protocol operates under mild conditions (Ph3PAuNTf2 5 mol %, DCE, 60 °C) with a good tolerance to functional groups (23 examples and yields up to 98%). The obtained β-carboline systems represent a versatile synthetic platform with modifiable substituents for successive functionalizations. Control experiments indicate the crucial role of both the nature of reactants and the identity of employed catalysts in the developed cycloaddition.

Modular approach to non-aromatic and aromatic pyrroles through gold-catalyzed [3 + 2] cycloaddition of 2H-azirines and ynamides

“…In turn, ynamides are customizable, highly reactive alkynes, i.e. C-C diatomic synthons, and some impressive examples of their synthetic applications have been reported in the chemical literature [44][45][46][47][48][49][50][51][52][53][54] (including our recent works in this direction [55][56][57][58][59] ). If the retrosynthetic approach is applied, it would be expected that the integration of 2H-azirines and ynamides could lead to pyrrole products formed via the formal [3 + 2] cycloaddition.…”

Cycloaddition of 4-Acyl-1H-pyrrole-2,3-diones Fused at [e]-Side and Cyanamides: Divergent Approach to 4H-1,3-Oxazines

“…Since acyl(imidoyl)ketenes C were reported not to react with common nitriles (benzonitrile, acetonitrile) [19,24,25], we decided to develop our DOS approach to 4H-1,3-oxazines utilizing so-called push-pull nitrile system, viz. cyanamides (aminonitriles) 2, which are known to have higher reactivity in [4 + 2] cycloaddition reactions [26][27][28][29][30][31].…”

Insights into gold-catalyzed formation of aza-heterocycles using benzofuroxans as nitrene transfer reagents: mechanism and origins of chemoselectivity

“…Which one is a key step of the catalytic reaction? What is the solvent effect in the light of previous reports 15,16 ? Intrigued by α-imino gold carbenes and chemoselectivities, we here performed a systematic theoretical study to provide a better understanding of the intrinsic mechanism for prototypical reactions in this field.…”