abstract |
Squarylium compounds of the formula: wherein Q1 and Q2 are each independently a pyrylium, thiopyrylium, selenopyrylium, benzpyrylium, benzthiopyrylium or benzselenopyrylium nucleus, and R1 and R2 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 Q2CH2R2 in the presence of a base. |