Calcium carbide as a cost-effective starting material for symmetrical diarylethynes via Pd-catalyzed coupling reaction

Synthesis and photophysical properties of novel multisubstituted benzene and naphthalene derivatives with high 2D-π-conjugation

“…1. 1,2-Bis(2,2 0 -bithiophene-5-yl)acetylene (bbta) was obtained using [PdCl 2 (PPh 3 ) 2 ] as a catalyst precursor, copper(I) iodide as co-catalyst and triethylamine as base (for 5-iodo-2,2 0 -bithiophene synthesis see [31]). In contrast to the methods described in the literature [32][33][34] in which THF, DMF or acetonitrile were used as the solvent we chose acetone. Using of acetone increase the solubility of acetylene in the reaction medium (which mean higher concentration of this substrate) and, in turn, shortening reaction time.…”

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

“…Although calcium carbide is assumed to be the reactive species, most of the published methods use a certain amount of water, for the main purpose to help to dissolve calcium carbide by breaking up its polymeric structure . However, water reacts quickly with calcium carbide to form acetylene, so that not the solution of calcium carbide but the production of acetylene is important . Interestingly, calcium carbide or rather its protonated product acetylene, can be used as either dipolarophile, electrophile or nucleophile, underlining its diversity as reagent in organic synthesis.…”

“…The presence of small amounts of N ‐vinylpyrrole led to further investigation of vinylation reactions on indoles and phenols, alcohols, sugars, epoxides and thiols . As a nucleophile, calcium carbide can be involved in Sonogashira cross‐coupling reactions to form either internal alkynes through double cross‐coupling or intermediate terminal alkynes, although it is hard to control single coupling . Moreover, calcium carbide can react with various carbonyl moieties, such as aldehydes/ketones or imines generating acetylenic alcohols, propargyl amines, enaminones or (iso)quinolines by making use of its nucleophilic properties .…”

Using Calcium Carbide as an Acetylene Source for Cascade Synthesis of Pyrrolo[2,3‐b]quinoxalines via Copper‐Free Sonogashira Coupling Reaction

“…This strategy was successfully applied for the synthesis of enaminones and propargylic amines through the three‐component coupling reaction of CaC 2 , aryl aldehydes, and amines as well as a convenient method for the preparation of propargyl alcohols by reacting CaC 2 with aldehydes and ketones in the presence of 50 mol‐% of cesium carbonate in aqueous DMSO at 60 °C . Novel protocols have already been developed for the synthesis of various functional molecules such as propargylamines, diarylethynes, triazoles, and enaminones from calcium carbide. The use of ethynylmagnesium bromide has also been reported recently as a commercial acetylene surrogate in the Kumada–Negishi ‐type coupling reactions .…”