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.

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Synthesis and Reactivity of Propargylamines in Organic Chemistry

Synthesis of 3-pyrrolines, annulated 3-pyrrolines, and pyrroles from alpha-amino allenes.

A series of propargyl amides were prepared and their reactions with the Lewis acidic compound B(C6F5)3 were investigated. These reactions were shown to afford novel heterocycles under mild conditions. The reaction of a variety of N-substituted propargyl amides with B(C6F5)3 led to an intramolecular oxo-boration cyclisation reaction, which afforded the 5-alkylidene-4,5-dihydrooxazolium borate species. Secondary propargyl amides gave oxazoles in B(C6F5)3 mediated (catalytic) cyclisation reactions. In the special case of disubstitution adjacent to the nitrogen atom, 1,1-carboboration is favoured as a result of the increased steric hindrance (1,3-allylic strain) in the 5-alkylidene-4,5-dihydrooxazolium borate species.

Cyclisation versus 1,1-Carboboration: Reactions of B(C6F5)3 with Propargyl Amides

Enantioenriched propargyl mesylates or perfluorobenzoates react with α-(N-carbamoyl)alkylcuprates to afford scalemic α-(N-carbamoyl) allenes which undergo N-Boc deprotection and AgNO3-promoted cyclization to afford N-alkyl-3-pyrrolines. The synthetic sequence proceeds under optimal conditions with no loss of enantiopurity relative to the starting propargyl alcohols prepared by asymmetric addition of terminal alkynes to aldehydes.

Reaction of α-(N-Carbamoyl)alkylcuprates with Enantioenriched Propargyl Electrophiles: Synthesis of Enantioenriched 3-Pyrrolines

Synthesis and biological evaluation of (2,5-dihydro-1H-pyrrol-1-yl)-2H-chromen-2-ones as free radical scavengers

A convenient one-pot synthesis of n-aryl-3-pyrrolines

N -propargylanilines, under one-pot homologation conditions, undergo an in situ cyclisation catalysed by Cu(I) to yield 3-pyrrolines in good yield.

Karamil Jayaprakash

Papers

A convenient one-pot synthesis of n-aryl-3-pyrrolines

A Convenient One-Pot Synthesis of N-Aryl-3-pyrrolines.