| abstract |
A method of synthesizing a compound having a 1,3-thiazolidin-4-one ring appended at the 2-position by a double bond to the active methylene position of a ketomethylene or malononitrile moiety, which comprises reacting the corresponding ketomethylene compound or malononitrile with an isothiocyanate in the presence of a base, reacting the resulting product with a haloacetic acid or haloacetic ester, followed by eliminating water or alcohol to form the 1,3-thiazolidin-4-one ring. A fragment necessary to complete a merocyanine, oxonol, hemicyanine, benzylidene, cinnamylidene or holopolar cyanine dye can be appended to the 1,3-thiazolidin-4-one ring to obtain the desired dye. |