Water mediated deprotective intramolecular hydroamination of N-propargylaminopyridines: synthesis of imidazo[1,2-a]pyridines

Synthesis of Chiral Propargylamines, Chiral 1,2-Dihydronaphtho[2,1-b]furans and Naphtho[2,1-b]furans with C-Alkynyl N,N'-di-(tert-butoxycarbonyl)-aminals and β-Naphthols

Chiral phosphoric acid-catalyzed couplings of C-alkynyl N,N'-di-(tert-butoxycarbonyl)-aminals with β-naphthols led to chiral propargylamines in moderate to high yields with high to excellent enantioselectivity, in which the reactions underwent sequential chiral phosphoric acid-catalyzed in situ formation of N-(tert-butoxycarbonyl)-imines (N-Boc-imines) from the aminals, and 1,2-addition of β-naphthols to the N-Boc-imines. Chiral 1,2-dihydronaphtho[2,1-b]furans and naphtho[2,1-b]furans were prepared with satisfactory results when 10 mol% AgOAc and 20 mol% 2,6-lutidine or 1.2 equiv. of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) were added to the resulting chiral propargylamines solution, respectively.

Metal-free multicomponent approach for the synthesis of propargylamine: a review

Propargylamines are important classes of alkyne coupled amine compounds used in heterocyclic chemistry and pharmaceuticals chemistry and have a large impact as a pharmacophore used in medicinal chemistry. One of the straightforward approaches for the synthesis of this class of compound is A3 coupling, a three-component coupling reaction among aldehyde, alkyne (terminal acetylene) and amine. However, there are many methods other than conventional three component alkyne–aldehyde–amine (A3) coupling which have also been reported for the synthesis of propargylamine. Most of these methods are based on the metal catalyzed activation of terminal alkyne. From the perspective of green and sustainable chemistry, the scientific community should necessarily focus on metal-free techniques which can access a variety of propargylamines. There are only a few reports found in the literature where propargylamines were successfully synthesized under metal-free conditions. This present review article neatly and precisely encompasses the comprehensive study of metal-free protocols in propargylamine synthesis putting forth their mechanisms and other aspects.

Metal-free propargylamines synthesis via multicomponent reactions.

Synthesis and Reactivity of Propargylamines in Organic Chemistry

Propargylamines are a versatile class of compounds which find broad application in many fields of chemistry. This review aims to describe the different strategies developed so far for the synthesis of propargylamines and their derivatives as well as to highlight their reactivity and use as building blocks in the synthesis of chemically relevant organic compounds. In the first part of the review, the different synthetic approaches to synthesize propargylamines, such as A³ couplings and C-H functionalization of alkynes, have been described and organized on the basis of the catalysts employed in the syntheses. Both racemic and enantioselective approaches have been reported. In the second part, an overview of the transformations of propargylamines into heterocyclic compounds such as pyrroles, pyridines, thiazoles, and oxazoles, as well as other relevant organic derivatives, is presented.

New protocols to access imidazoles and their ring fused analogues: synthesis from N-propargylamines

Imidazole and its derivatives are privileged N-heterocyclic structures present in various natural products and synthetic pharmaceuticals.

Visible-light-promoted selective C–H amination of heteroarenes with heteroaromatic amines under metal-free conditions

The regioselective C–H amination of quinoline amides (C5) and imidazopyridines (C3) under transition-metal-free conditions at room temperature with a high degree of functional group tolerance is reported.

Lewis Acid-Catalyzed Denitrogenative Transannulation of Pyridotriazoles with Nitriles: Synthesis of Imidazopyridines

The synthesis of imidazo[1,5-a]pyridines through denitrogenative transannulation of pyridotriazoles with nitriles using BF₃·Et₂O as catalyst has been described. The combination of solvents (dichlorobenzene-dichloroethane) plays a crucial role in achieving quantitative yields of desired products under metal-free conditions.

Copper-catalyzed aerobic oxidative amination of C(sp3)–H bonds: synthesis of imidazo[1,5-a]pyridines

Copper-catalyzed synthesis of imidazo[1,5-a]pyridine-1-carboxylates through oxidative amination of C(sp³)–H bonds under mild aerobic conditions with broad substrate scope has been achieved.

Substrate selective synthesis of pyrazolo[1,5-a]pyridines through [3 + 2] cycloaddition of N-aminopyridines and β-nitro styrenes

Synthesis of 2 or 3-(hetero)aryl pyrazolo[1,5-a]pyridines through [3 + 2] cycloaddition ofN-aminopyridine with β-nitrostyrenes followed byin situdenitration under metal-free and mild conditions are described.

Copper-mediated synthesis of pyrazolo[1,5-a]pyridines through oxidative linkage of C–C/N–N bonds

Copper-mediated synthesis of pyrazolo[1,5-a]pyridine-3-carboxylates through oxidative linkage of C–C and N–N bonds under mild reaction conditions with broad substrate scope is described.