Synthesis, characterization and antimycobacterial studies of ethyl 6-(4-chlorobenzoyl)-1,1-dioxo-3,5-diaryl-1,4-thiazinane-2-carboxylates using the green catalyst L-Proline

The four component reaction of ethyl 2-[(2-oxo-2-arylethyl)sulfonyl]acetate, aromatic aldehyde and primary amine/ammonia in a 1:2:1 molar ratio in the presence of L-proline (30 mol %) in ethanol at room temperature for 2-4 hours afforded the [1,4]-thiazine in good yields (75-90 %) . Two [1,4]-thiazines described in the present work, have been previously reported by Reddy et al. albeit in lower yields (72 and 69% respectively) from the reaction of ethyl[(2-oxo-2-arylethyl)sulfonyl]acetate with aromatic aldehyde and ammonium acetate in ethanol, than that obtained in the present study employing (L)-proline (90 and 88% respectively).