The possibility of using 2-chloroacetylphenothiazine (1) for the synthesis of thiazole moieties has been studied. In addition, we have investigated the convertion of 1 to methyl phenothiazine-2-glyoxylate (5) and phenothiazine-2-glyoxaldehyde (7) by the action of SeO2/CH3OH and dimethylsulphoxide respectively.