ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Addition-cyclization reactions of (Z)-2,3-diphenylpropenoyl isothiocyanate with aniline and diphenylamine

M. Dzurilla, P. Kutschy, P. Kristian, and D. Koščik

Department of Organic Chemistry, Faculty of Natural Sciences, P. J. Šafárik University, CS-041 67 Košice

Abstract: The reaction of (Z)-2,3-diphenylpropenoyl isothiocyanate with aniline and diphenylamine has been studied. The stable thiourea, formed in the reaction with aniline, in the presence of Lewis acid (BF₃ • Et₂0) cyclizes to cis 5,6-diphenyl-2-phenylamino-5,6-dihydro-4H-1,3-thiazin-4-one. In alkali medium cis-l,3-thiazine undergoes Dimroth rearrangement under forma­tion of cis-l,5,6-triphenyl-2-thiouracil. N-Phenyl-N'-(2,3-diphenylpropenoyl)thiourea at similar conditions affords a mixture of cis- and trans-2-thiouracils. In the reaction with triethylamine both isomers can be iso­lated. Isomerization of trans-2-thiouracil tc the cis isomer has been studied simultaneously. Diphenylamine with 2,3-diphenylpropenoyl isothiocyanate gives a mixture of cis- and trans-l,3-thiazines. It was impossible to isolate the corresponding thiourea as cis-l,3-thiazine was formed already at low temperature.

Full paper in Portable Document Format: 442a221.pdf

Chemical Papers 44 (2) 221–228 (1990)