G. M. Gavrilova

Reactions of 3,6-bis(vinylsulfonyl)-1,2,4,5-tetrafluorobenzene with thiosemicarbazide and thiourea

3,6-Bis(2-thiosemicarbazidoethylsulfonyl)-1,2,4,5-tetrafluorobenzene has been prepared in up to 77% yield by reacting 3,6-bis(vinylsulfonyl)-1,2,4,5-tetrafluorobenzene with thiosemicarbazide (ratio 1:2) in ethanol or in DMF (20°C). Unexpectedly, with a four-fold amount of thiosemicarbazide at 70–80°C (DMF), the reaction afforded a fluorinated nitrogen- and sulfur-containing fused heterocycle, 2-amino-8,9-difluoro-10-(2-thiosemicarbazidoethylsulfonyl)-5,6-dihydrobenzo[h,i]-1,4-thiazino[4,3-d]-1,3,4-thia- diazin-7,7-dioxide (54% yield). The use of tributylamine produced this heterocycle from 3,6-bis(2-thiosemicarbazidoethylsulfonyl)-1,2,4,5-tetrafluorobenzene in 80% yield along with 2-amino-8,9-difluoro-5,6-dihydrobenzo[h,i]-1,4-thiazino[4,3-d]-1,3,4-thiadiazine-7,7-dioxide (18% yield).

Synthesis of polyfunctionally substituted benzothiazines based on vinylthionahlobenzenes and 2-mercaptoethylamine

Regioselective nucleophilic substitution of the fluorine atoms in positions 2 and 5 of the benzene ring takes place in the reaction of 3,6-bis(vinylthio)-1,2,4,5-tetrafluoro- and 3-vinylthio-6-chloro-1,2,4,5-tetrafluorobenzenes with 2-mercaptoethylamine in isopropyl alcohol-water-dimethylformamide mixture at 40–45°C in the presence of KOH. The products of disubstitution obtained are converted into 1,4-benzothiazines on heating to 100°C in dimethylformamide in the presence of K2CO3 as a result of intramolecular substitution.

Unexpected Reaction of Thiosemicarbazide with 3,6-Bis(vinylsulfonyl)-1,2,4,5-tetrafluorobenzene

Compound 2 was obtained as a result of nucleophilic addition of thiosemicarbazide to the activated vinyl group of sulfone 1 and subsequent intramolecular substitutions of the fluorine atoms of the benzene ring in the ortho position with participation of the NH group, and in the meta position with participation of the second nucleophilic center of the thiosemicarbazide, the sulfur atom. We described examples of simultaneous participation of the NH2 group of amines in nucleophilic addition and substitution reactions [1,2]. The reaction proceeds with a four-fold molar excess of thiosemicarbazide in DMF at 70°C. The structure of compound 2 was proven by IR and NMR (H, C, F, and N) spectroscopy. The H, C, F, and N NMR spectra were recorded on a Bruker DPX 400. Operating frequencies: H 400.13 MHz, C 100.61 MHz, F 376.50 MHz, and N 40.54 MHz. The N NMR spectrum, obtained by the DEPT technique with N-H spin-spin coupling constants of 90 Hz, contains only the chemical shifts for the nitrogen atoms directly bonded to protons.

Unexpected Reaction of 3,6-Bis(vinylsulfonyl)-1,2,4,5-tetrafluorobenzene with Thiosemicarbazide

Abstract

Vinylthiylation of Octafluorotoluene and its Derivatives

Abstract