Structure elucidation and DFT-study on substrate-selective formation of chalcones containing ferrocene and phenothiazine units. Study on ferrocenes, Part 17

By means of base-catalysed condensation of 1-acyl-/1,1′-diacylferrocenes (acylformyl or acetyl) with 3-formyl- and 3,7-diacetylphenothiazines a series of novel mono- and bis-chalcones were prepared. The enhanced reactivity of the enolate anions of the mono-chalcone intermediates relative to that of the enolates of the corresponding diacetyl-substituted precursor was interpreted by the electron-releasing effect of the ferrocenyl- or phenothiazinyl group present in the β position of the enone subunit. The structures of the novel products were evidenced by IR, 1H and 13C NMR spectroscopy including 2D-COSY, 2D-HSQC and 2D-HMBC measurements.