2-(phenylethynyl)-3-phenyl-1,4-dimethylnaphthalene and the method of its preparation

Abstract

The subject of the application is 2-(phenylethynyl)-3-phenyl-1,4-dimethylnaphthalene and a method for its preparation consisting in introducing ethyl 2-methylacetoacetate into a reactor, and per 1 mmol of this compound the following are added: from 1 to 5 mmol of 1,4-diphenyl-1,3-butadiyne, from 25 to 250 mg of molecular sieves, from 0.01 to 0.1 mmol of catalyst, i.e. bromo-tri(carbonyl)-(tetrahydrofuran)rhenium(I) dimer, and from 1 to 20 ml of low-boiling alkylbenzene, after which the resulting reaction mixture is stirred and simultaneously heated at a temperature of 120°C to 220°C for a time of 1 to 120 hours, then the post-reaction mixture is cooled to ambient temperature, after which - also per 1 mmol of ethyl 2-methylacetoacetate - from 1 to 5 mmol of cesium fluoride, from 1 to 20 ml of acetonitrile and from 0.5 to 2 mmol of benzine precursor, i.e. 2-(1-trimethylsilyl)phenyl trifluoromethanesulfonate, and the whole is stirred at a temperature of 10°C to 50°C for 1 to 120 hours,then, in the next stage, volatile fractions are evaporated from the reaction mixture using a vacuum rotary evaporator, and the crude product is isolated from the solid residue by column chromatography on silica gel using a low-boiling saturated hydrocarbon - low-boiling chlorinated hydrocarbon system as the eluent, mixed in a volume ratio of 20:1 to 1:25, and then, preferably, the crude product is purified by carrying out another column chromatography process on silica gel using a low-boiling saturated hydrocarbon - low-boiling aromatic hydrocarbon system as the eluent, mixed in a volume ratio of 20:1 to 1:25. Finally, 2-(phenylethynyl)-3-phenyl-1,4-dimethylnaphthalene is obtained with a yield of up to 80% and a purity of not less than 98%. The product can be used for further expansion of the pi-electron system and can also be modified, e.g. by oxidation of methyl groups.