Propargylamines are an important class of organic compounds that have been widely used as building blocks for the synthesis of various kinds of chemically and biologically relevant compounds. Over the last few years, there have been a rapid growth in the research dedicated to developing the synthetic protocol for propargylamine derivatives. Among various methods that are reported for the synthesis of propargylamines, the three‐component coupling of aldehyde, amine and alkyne (commonly termed as A3 coupling reactions) secured a special place because of its convenient/atom economical approach and thus broadly used by researchers. Our aim in this review is to highlight the most recent advancement on A3 coupling reactions for the synthesis of various propargylamine derivatives as well as on the developments of subsequent transformation of these compounds to useful heterocyclic compounds and the related products.

Herein, we describe the preparation of sulfonimidoyl azides, and demonstrate their utility in the construction of N‐acyl sulfonimidamides and N‐sulfonimidoyl amidines. N‐Acyl sulfonimidamides were synthesized in good to very good yields via “on water” copper‐catalyzed three‐component coupling between sulfonimidoyl azide, alkynes and water. The use of amines as nucleophiles yielded a wide range of N‐sulfonimidoyl amidines. Both reactions were completed in very short time at room temperature under mild conditions, thus establishing the potential of sulfonimidoyl azides, the aza‐analogues of sulfonyl azides, as an excellent precursor to derive functionalized sulfonimidamides in one step.magnified image

A visible‐light (456 nm) promoted dual catalytic (cobalt‐/photoredox) method for the direct synthesis of sulfonimidoyl guanidine via three‐component reaction of aryl amine, isonitrile and sulfonimidoyl azide (as nitrene source) is developed. The protocol is fast, mild and provides products with a wide range of substrates in 56–86% yields. Additionally, the replacement of aryl amine with alcohol and thiol as nucleophile leads to the formation of sulfonimidoyl isourea and sulfonimidoyl isothiourea respectively, which are not yet reported in the literature.