New Thiazolidinones, Thiazolines and Thiopyrimidines from 3,5-Diphenylcyclohex-2-enone

1-(3,5-Diphenylcyclohex-2-enylidene)hydrazine 3 was prepared and used as a key intermediate for the synthesis of thiazolidin-5-one 6, thiazolidn-4-one 7, thiazolines 8a,b, 9 and thioxodihydropyrimidine 10. Base catalyzed Knoevenagel condensation of compounds 6, 7 and 10 with different aldehydes gave the arylidene derivatives 11a,b, 12a,b and 13a,b re-spectively. Treatment of compounds 6, 7 and 10 with different aromatic diazonium salts gave azodye derivatives 14a,b, 15a,b and 16a,b. The newly synthesized compounds were characterized by IR, 1 H-NMR and mass spectral data.


Results and Discussion
The key intermediate, 3 required for the synthesis of the title compounds was prepared according to the procedure outlined in the Scheme 1. For the synthesis of 3, reaction sequence including the first step decarboxylation of ethyl 2-oxo-4,6-diphenylcyclohex-3-ene carboxylate 1 either by a previously reported procedure [35] with NaOH solution or our new methodology using acetic acid gave3,5-diphenylcyclohex-2-enone 2. This was reacted with hydrazine hydrate to afford 1-(3,5-diphenylcyclohex-2-enylidene) hydrazine 3 in excellent yield. The structures of the synthesized compounds (2 and 3) were confirmed by IR, 1 H-NMR and mass spectral analyses. The IR spectrum of compound 2 no absorption was appeared for the ester group. The mass spectrum of 2 showed the molecular ion peak at m/z= 248 (M + , 100%) which is equivalent to the molecular formula (C 18 H 16 O). The mass spectrum of compound 3 showed the molecular ion peak at m/z = 262 (M + , 100%), corresponding to the molecular formula (C 18  The base promoted nucleophilic addition of 1-(3,5-diphenylcyclohex-2-enylidene)hydrazine 3 to an equimolar amount of phenyl isothiocyanate in dry DMF containing potassium hydroxide afforded the corresponding non isolable potassium N'-3,5-diphenylcyclohex-2-enylidene-Nphenylcarbamoylhydrazonothionate 4. In situ cyclization of intermediate 4 with chloroacetyl chloride afforded the corresponding 2-(3,5-diphenylcyclohex-2-enylidene)hydrazono) 3-phenylthiazolidin-5-one 6. The cyclized product 6 was also obtained upon treatment of thiosemicarbazone 5 with chloroacetyl chloride in dry DMF containing potassium hydroxide. The IR spectrum of compound 6 showed cyclic carbonyl absorption at 1680 cm -1 . The 1 H-NMR spectrum of 6 showed a singlet signal equivalent to two protons at δ 4.10 due to the methylene protons at C-4 of the thiazolidine ring (CO-CH 2 -N).
Structures 7-10 were established on the basis of both spectral data and elemental analyses. For example, The IR spectrum of 7 showed absorption band at 1727 cm -1 attributed to C=O groups. Its 1 H-NMR spectrum displayed a singlet signal equivalent to two protons at δ 3.97 (COCH 2 -S). The mass spectrum measurement gave an evidence for the proposed structure, which showed the molecular ion peak at m/z = 437(M + , 100%), corresponding to the molecular formula (C 27 H 23 N 3 OS). (c.f. experimental). The 1 H-NMR spectrum of 9 revealed singlet signal due to methylene group (-S-CH 2 -C=NH) at 3.96 ppm.
As a continuation of our studies on the synthesis of heterocyclic azo dyes [33,34,38,39], scheme 3 the behaviour of compounds 6, 7 and 10 toward arenediazonium chlorides was studied. Thus, 6, 7 and 10 was reacted with p -chlorobenzendiazonium chloride and p-methoxybenzendiazonium chloride in pyridine to give the corresponding azo -derivatives 14a,b, 15a,b and 16a,b respectively. Confirmation of the structures 14a,b -16a,b was based on analytical and spectral data. 1 H-NMR of 14a,b were characterized by the presence of the singlet signal of methyne (C 4 -H) group at δ = 3.5 ppm.

Conclusions
In conclusion, conducting reactions using thiocarbamoyl derivatives is an effective method for reactions leading to various C-C and C-N bond forming reactions. New thiazolidin-5-ones and 4-ones are of great importance, which were synthesized. The corresponding arylidines and arylazo derivates were also prepared.

Experimental
All melting points were determined on Gallenkamp electric melting point apparatus and were uncorrected. Elemental analyses were carried out at the Microanalytical Unit at Faculty of Science, Mansoura University, Egypt. IR spectra were recorded on a Mattson 5000 Fourier transform infrared (FTIR) spectrometer. The 1 H NMR spectra were measured on a Bruker WP 300 in CDCl 3 and DMSO-d 6 as solvent using tetramethylsilane (TMS) as an internal standard. Mass spectra were recorded on a Finnigan MAT 212 instrument at the Microanalytical Unit at Faculty of Science, Cairo Uni-versity, Egypt. Compound 1 and 2 were prepared according to a previously reported method [35].