Synthesis and structures of some new thiazolidin-4-ones and thiazolin-4-ones of anticipated biological activity

The condensation of omega-(4-formylphenoxy) acetophenone (3a) and its 4-bromo derivative (3b) with 2-thioxo-1,3-thiazolidin-4-one (4a) and 1,3-thiazolidin-2,4-dione (4b) in refluxing acetic acid in the presence of sodium acetate gave new E-5-arylmethylene-2-thioxo-1,3-thiazolidin-4-one (5a and 5b) and E-1,3-thiazolidin-2,4-dione (5c and 5d) derivatives in good yields, respectively. However, treatment of E-(5a and 5b) with piperidine ( or morpholine) in refluxing ethanol afforded new E-5-arylmethylene-2-piperidinyl (or morpholinyl)-1,3-thiazolin-4-3one derivatives (6a-d). The structures of all new compounds were established from microanalytical and spectral data.