Acetylene and its Derivatives in Reactions with Nucleophiles: Recent Advances and Current Trends
Abstract:Acetylene is a multi-thousand ton chemical feedstock now mainly produced by pyrolysis of hydrocarbons. In a view of the rapid depletion of hydrocarbon resources, acetylene and its derivatives, which can alternatively be manufactured from coal and other carbon-containing materials, including wastes, are expected to acquire increasingly more important role as universal chemical intermediates and building blocks. The high and flexible reactivity of these compounds makes the syntheses with their participation easier and less energyconsuming than those with alkenes.
Nucleophilic attack at the acetylenic moiety leads to diverse vinyl compounds, acetylenic alcohols, allenes, 1,3- dienes and heterocycles.
In the review, the recent advances both in modernization of classic reactions of acetylene and its derivatives with nucleophiles (superbase-catalyzed vinylation of alcohols, polyols, thiols, ethynylation of carbonyl compounds, prototropic rearrangements) are analyzed from modern positions. The new reactions: direct vinylation of sulfide, selenide and telluride ions, elemental sulfur, selenium, tellurium, phosphorus, oximes and amidoximes, synthesis of pyrroles from ketoximes, direct synthesis of 2-vinyloxy-1,3-alkadienes by superbase-catalyzed hydrative trimerization of acetylene are also considered within the same framework.
A special emphasis is made on the activation of acetylenes and nucleophiles in superbase media such as MOH / DMSO, MOH / NMP (M = Na, K, Rb, Cs) and the like.
Quantum chemical calculations of the complexing of acetylene with MOH and its role in the nucleophilic reactions of acetylene and its derivatives are revisited.
Most recent syntheses of functionalized pyrroles, thiophenes, dihydropyridines, quinolines and other fundamental heterocycles by the reaction of carbanions of propargyl and allene derivatives with isothiocyanates are also briefly reviewed.