Annulation of 2‐Alkynylanilines: The Versatile Chemical Compounds

Abstract

2-Alkynylanilines as versatile building blocks have been widely applied for the construction of nitrogen atomcontaining heterocycles in organic synthesis. The focus of this review is on the application of 2-alkynylaniline and its derivatives in the metal-catalyzed or metal-free synthesis of various heterocycles including indoles, oxindoles, indazoles, benzisoxazoles, quinolines, benzoxazines, benzothiazines, quinazolines, cinnolines, and seven-and eight-membered heterocycles.

Synthesis of Nitrogen-Containing Heterocyclic Scaffolds through Sequential Reactions of Aminoalkynes with Carbonyls

“…Versatile β-aminoalkyne building blocks for the synthesis of nitrogen-containing heterocyclic compounds are represented by 2-alkynylanilines 38 [ 55 , 56 , 57 ]. Their sequential reaction with carbonyl derivatives was directed towards the formation of different scaffolds by changing the reaction conditions.…”

A regiodivergent Truce–Smiles rearrangement: a strategy for the synthesis of arylated indoles promoted by KN(SiMe3)2

“…Both intra and intermolecular cyclizations of 2-alkynylaniline derivatives have become popular strategies for indole synthesis and functionalization. 53,54 The approach typically starts with aminometallation of the CuC bond, usually with the aid of a transition metal catalyst. It can be followed by a 1,3-migration of functional groups from the metalated indole nitrogen, including allyl, 55,56 propargyl, 57 sulfonyl, 58 and α-alkoxyalkyl 59 moieties (Scheme 1a).…”

Base-Promoted Tandem Synthesis of 2-Substituted Indoles and N-Fused Polycyclic Indoles

“…Traditional routes include the Fischer indole synthesis, Bartoli indole synthesis, Bischler indole synthesis, , and Fukuyama indole synthesis . Recently, the transition-metal-catalyzed cyclization of 2-alkynylaniline derivatives has become a popular method to access functionalized indoles. − This approach has the additional benefit that it enables functionalization of the C 3 position of the indole via N to C 3 migration. Examples of migrating groups include allyl, , acyl/formyl, , alkenyl, , methyl, propargyl, , and sulfonyl groups .…”