A regioselective method for the preparation of p-tolyl-substituted alkanes based on the reaction of dialkyl-substituted alkynes with 4 equiv. of TaCl₅ or NbCl₅ in the presence of stoichiometric amounts of metallic magnesium in toluene solution. It was found that the reaction of 5-decyne with the TaCl₅-M reagent system (where М = Mg, Zn, Fe, Sm, Al, Mn) in a toluene solution is accompanied by the selective formation of 1-(decan-5-yl)-4-methylbenzene in a high yield (79-90%). The effect of solvents on the selectivity of the conversion of 5-decyne under the action of the TaCl₅-Mg reagent system has been studied.