In an attempt to develop new thiazinanones, 2-oxoacenaphthylen-1(2H)-ylidene)hydrazineylidene)-5,6-diphenyl-1,3-thiazinan-4-ones were synthesized via the reaction of oxoacenaphthylen-hydrazinecarbothioamide derivatives with 2,3-diphenylcycloprop-2-enone in ethanol and catalyzed by triethyl amine. The structure of the obtained thiazinanones was elucidated by spectral data (IR, MS, 1H and 13C NMR spectra) in addition to elemental analysis. The mechanism describes the reaction pathway was also discussed. [ABSTRACT FROM AUTHOR]