The Use of Calcium Carbide as Acetylene Source in a Three‐Component Coupling with ω‐Chlorinated Ketones and Primary Amines

Abstract

Calcium carbide was used in a Cu -catalysed three-component coupling with ω-chlorinated ketones and primary amines to generate terminal 2-alkynyl-N-heterocycles. The formation of an imine and the subsequent intramolecular substitution results in an active electrophilic iminium species, which can be alkynylated by in situ formed copper acetylide. A number of aliphatic primary (functionalised) amines and aliphatic or aromatic alkynes together with different alkyl- or aryl-substituted γ- or δ-chloroketones could be used. Simple acid-base workup instead of column chromatography can be applied to obtain the resulting 2-alkynylpyrrolidines and 2-alkynylpiperidines.

Calcium‐Based Sustainable Chemical Technologies for Total Carbon Recycling

“…The workup is simplified to solvent evaporation. The same reactor was used in the synthesis of 2‐alkynyl‐ N ‐heterocycles under copper(I)‐catalyzed conditions . This elegant approach, based on alkynylation of active electrophilic iminium species by in situ‐formed copper acetylide, opened a convenient pathway to valuable series of aryl‐substituted chloroketones.…”

“…Interestingly, carbide in this procedure plays a dual role: a source of acetylene and a drying agent. Under the reaction conditions, not only the copper salts but also silver and gold salts can catalyze this transformation . Model deuterium incorporation, which was performed according to the developed methodology, produced a series of novel 4,5‐dideuteropyrazoles with excellent deuterium enrichment.…”

“…The same reactor was used in the synthesis of 2-alkynyl-N-heterocycles under cop-per(I)-catalyzed conditions. [72] This elegant approach, based on alkynylation of active electrophilici minium species by in situformed coppera cetylide, opened ac onvenient pathway to valuable series of aryl-substituted chloroketones. Interestingly, carbidei nt his procedure plays ad ual role:as ource of acetylene andadrying agent.U nder the reaction conditions, not only the copper salts but also silver andg olds alts can catalyze this transformation.…”

“…Interestingly, carbidei nt his procedure plays ad ual role:as ource of acetylene andadrying agent.U nder the reaction conditions, not only the copper salts but also silver andg olds alts can catalyze this transformation. [72] Model deuteriumi ncorporation, which was performed according to the developed methodology,p roduced as eries of novel 4,5-dideuteropyrazoles with excellent deuterium enrichment.T his appears to be a1 ,3-dipolar cycloaddition, which proceedsv ia ac oncerted transition state, and appropriate theoretical calculations confirm good functional group tolerance for the key cycloaddition step. Pyrazoles can also be synthesized from calcium carbide and tosylhydrazones.…”

Understanding the solubilization of Ca acetylide with a new computational model for ionic pairs

“…Many metal acetylides are known, including acetylides of practically all classes of metals, [1][2][3][4][5][6][7][8][9][10] and bi-metallic acetylides. [11][12][13] Among metal acetylides, widely produced CaC 2 now appears to be the most versatile choice for the synthesis of organic substances, including those biologically active, [14][15][16][17][18][19][20][21][22][23][24] as well as that of monomers. [25][26][27] Moreover, CaC 2 is envisioned to become the feedstock for the sustainable, carbon-neutral chemical industry.…”