PURPOSE: To prepare a benzoquinone derivative useful as a medicine, e.g. a remedy for heart failure, vitamin K1, vitamin K2, etc., easily, in high yield without using a fatally poisonous substance, by reacting a paraquinone derivative with an allyl tin derivative in the presence of a Lewis acid catalyst.

CONSTITUTION: A compound I (X is two groups of methoxy, methyl or II) is condensed with a compound III (R is alkyl or phenyl; Y is IV or V; n is integer of 1W9) in the presence of a Lewis acid (pref. boron trifluoride etherate) to give the compound VI. The reaction is carried out in a solvent, e.g. halogenated hydrocarbons, ethers, etc. The reaction is initiated at a low temperature (≤0°C) and the temperature is slowly raised to complete the reaction. The compound III is a new material and prepared by reacting a trialkyl tin halide with an alkali metal and reacting the product with an allyl halide derivative.