The Construction of Nitrogen‐Containing Heterocycles from Alkynyl Imines

Abstract

Nitrogen‐containing heterocycles have attracted considerable attention due to their extensive applications in the fields of organic synthesis, pharmaceuticals, agrochemicals, and materials science. This review focuses on the recent advances in the synthesis of nitrogen‐containing heterocycles via the cyclization of alkynyl imines. By using this protocol, a variety of nitrogen‐containing heterocycles, mainly including four‐, five‐, six‐, and seven‐membered nitrogen‐containing heterocycles, aza‐spirocycles, and fused aza‐heterocycles, could be obtained efficiently under mild conditions. Additionally, mechanistic features of these transformations are also discussed.

One-pot Double Annulations to Confer Diastereoselective Spirooxindole-pyrrolothiazoles

“…Next, the stepwise process was also carried out by using the thioproline 3a (1 eq.) with 86% of isolated yield and 1.1:1.0 of 1a:4a through decarboxylative [3+2] cycloaddition (Table 1, entry 6), which afforded compound 5a with 73% isolated yield at 90 o C for 9 h. Notably, we conferred cascade reaction process to synthesize compound 5a with 70% isolated yield as one-step four-component reaction (4-CR) with 2.2:1.1:1.0 of 1a:2:4a at 90 o C for 9 h in EtOH after variations of solvents, reaction time and temperature with one operational step (Table 1, entries [7][8][9][10][11][12]. This 4-CR reaction is the first example of double annulations with sequential N, S-acetalation and [3+2] cycloaddition for diastereoselective spirooxindole-pyrrolothiazoles by the formation of two new rings, 5 bonds, and 5 stereocenters without intermediate purification.…”

“…The nitrogen-containing heterocycles play a dominant role as a structural fragment of therapeutic agents in medicinal chemistry and drug discovery [1][2][3][4][5][6][7][8][9]. The nitrogen-containing 2 heterocyclic moieties are currently discovered in the more than 75% of drugs available in the market approved by the FDA.…”

Synthesis of indolo- and benzothieno[3,2-c]quinolines via POCl3 mediated tandem cyclization of o-alkynylisocyanobenzenes derived from o-alkynyl-N-phenylformamides

“…1 Therefore, efforts towards the development of novel and effective approaches for constructing various nitrogen-containing heterocyclic frameworks continue to be a focus in the synthetic organic community. 2 Among a broad collection of nitrogen-containing heterocycles, those bearing quinoline, fused with indole scaffolds belong to a class with pharmacological and therapeutic importance. In particular, indolo[3,2- c ]quinolines are an important motif found in natural products 3 and synthetic molecules.…”

Copper-Catalyzed Regio- and Stereoselective Sulfonylation of Alkynyl Imines with Sulfonyl Hydrazides: Access to (E)-β-Sulfonyl Enones

“…Considering that sulfonyl hydrazides have emerged as efficient and powerful sulfonyl sources in organic synthesis, a palladium-catalyzed coupling of aryl propiolates and sulfonyl hydrazides for the synthesis of ( E )-β-aryl sulfonyl acrylates has been well established by Jiang’s group (Scheme d) . However, the above excellent examples are achieved by addition reactions; to the best of our knowledge, the coupling reaction of alkynyl imines with sulfonyl hydrazides to access of ( E )-sulfonyl enones via free radical process has been not reported. Herein, we present a copper-catalyzed sulfonylation of alkynyl imines with sulfonyl hydrazides to furnish a series of ( E )-β-sulfonyl enones with excellent regio- and stereoselectivity and yields (Scheme e).…”