Stereochemistry, tautomerism, and reactions of acridinyl thiosemicarbazides in the synthesis of 1,3-thiazolidines

Autor: Lucia Sucha, Pavol Kristian, Juraj Bernát, Kalevi Pihlaja, Mária Vilková, Ján Imrich, Eva Balentova, Karel D. Klika, Nada Prónayová
Rok vydání: 2006
Předmět:
Zdroj: Journal of Heterocyclic Chemistry. 43:645-656
ISSN: 1943-5193
0022-152X
Popis: Acridin-9-yl hydrazine upon treatment with various isothiocyanates (RNCS, R = methyl, allyl, phenyl, p-methoxy phenyl, and p-nitro phenyl) yielded the corresponding thiosemicarbazides with acridine substituted on the carbazide-type side. The alkyl-substituted compounds were present in solution as equilibria consisting of the major H-10, H-12 tautomer (either E or Z or both about the C13-N14 bond) and the minor H-10, SH tautomer (either E or Z or both). The major species for the aromatic-substituted compounds was the H-10, H-12 E tautomer, with the evident minor species being the H-10, H-12 Z tautomer. The thiosemicarbazides were each quantitatively converted into the analogous semicarbazides upon treatment with mesitylnitrile oxide wherein all structures were present in solution as the H-10 tautomers with Z conformation about the C13-N14 bond. Methylation of the compounds with methyl iodide yielded S-methylated compounds wherein the Z configuration dominated in each case over the E configuration along the N12-C13 double bond. Treatment of the thiosemicarbazides with methyl bromoacetate resulted in the formation of 1′,3′-thiazolidin-4′-ones wherein the Z configuration predominated in each case over the E configuration along the N12C13 double bond. With bromoacetonitrile as the bifunctional electrophile, the initial 1′,3′-thiazolidin-4′-imines that formed spontaneously underwent Dimroth-type rearrangement to the regiosiomeric 1′,3′-thiazolidin-4′-imines.
Databáze: OpenAIRE
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