Synthesis of squarylium compounds

摘要

Squarylium compounds of the formula: wherein Q<1> and Q<2> are each independently a pyrylium, thiopyrylium, selenopyrylium, benzpyrylium, benzthiopyrylium or benzselenopyrylium nucleus, and R<1> and R<2> are each independently an aliphatic or cycloaliphatic group, can be prepared by reacting a squaric acid derivative of the formula: with a compound of the formula Q<2>CH2R<2> in the presence of a base. The derivatives of Formula II may be prepared by condensing a 2,3,4,4-tetrahalocyclobut-2-en-1-one with a compound of the formula Q<1>CH2R<1> in the presence of a base to produce a compound of the formula: wherein Q<1> and R<1> are as defined above, and X represents chlorine or bromine, and hydrolyzing the compound of Formula III. Alternatively, the derivatives of Formula II may be prepared by reacting a diester, monoacid chloride monoester or diacid chloride of squaric acid with a compound of the formula Q<1>CH2R<1> in the presence of a base, followed by hydrolysis of the resultant monoacid chloride or monoester derivative of the compound of Formula II to the parent compound.