Piperazine-2-thione

Catalytic reduction of 2-hydroxyiminopiperazine over Raney nickel afforded 2-iminopiperazine (90) (1614). This was converted by methanolic hydroxylamine at room temperature to 2-hydroxyiminopiperazine, and by hydrogen sulfide to piperazine-2-thione (1614). Reduction of 4-benzoylpiperazin-2-one with sodium borohydride in pyridine formed 1-benzylpiperazine and 4-benzylpiperazin-2-one, but reduction with sodium borohydride in triethylamine gave only some 1-benzoyl-piperazine (1617). Piperazin-2-one with amyl nitrite in butanol produced 4-nitroso-piperazin-2-one (1614), and 3-(l, l-ethylenedioxy)ethyl-l,4-dimethylpiperazin-2-one (87) with ethanolic hydrogen chloride gave 3-acetyl-1,4-dimethylpiperazin-2-one (91) (1594). 

Iminopiperazine when treated with hydrogen sulfide gives piperazine-2-thione (1614), and A -(aminoacyl)aminoacetonitrile with ammonium hydrogen sulfide gave 5-thiopiperazin-2-one (1619). Piperazine-2,5-dithione may be prepared from aminoacetonitrile and hydrogen sulfide in ammoniacal solution (1642). 

The identification of the HIV-1-specific non-nucleoside reverse transcriptase inhibitors (NNRTIs) as a separate class of HIV inhibitors was heralded by the discovery of the tetrahydroimidazo[4,5,1 -// .][ 1,4]benzo-diazepin-2(l //)-onc and -thione (TIBO) derivatives (Fig. 7) [58,59] and 1 -(2-hydroxyethoxymethyl)-6-(phenylthio)thymine (HEPT) derivatives (Fig. 8) [60,61]. The first TIBO derivatives (R82150, R82913) were the first NNRTIs [58] postulated to act as inhibitors of HIV-1 RT [59], For the HEPT derivatives it became evident that they also interact specifically with HIV-1 RT after a number of derivatives (i.e., E-EPU, E-EBU, and E-EBU-dM) had been synthesized that were more active than HEPT itself [62,63]. Following HEPT and TIBO, several other compounds, i.e., nevirapine, pyridinone, and bis(heteroaryl)piperazine (BHAP), were... 

Chloro-47/-pyrido[l,2-a]pyrimidine-4-thione was obtained by the treatment of the 4-oxo derivative with Lawesson s reagent in boiling anhydrous toluene, and then the 2-chloro atom was changed for a piperazino group with piperazine in boiling EtOH (00BMC751). Treatment of 7-chloro-3-propyl-2-propoxy-4/f-pyrido[ 1,2-a]pyrimidin-4-one with... 

Ci,H6N202, Hexahydro-3,6-pyridazine-dione, 41B, 270 Ci,H6N2S, 2H-Pyridaz-3-thione, 31B, 117 C4H8N2O, Perhydropyrimidin-2-one, 46B, 1153 CftH8N202f 2,6-Bishydroxyiminopiperazine, 46B, 221 Ci,HioN2f Piperazine (gas-ed), 28, 666 37B, 687... 

Thiazolo[5,4-6]pyridines [CsNS-CsN].—Condensation of 3-amino-2-chloropyri-dine with carbon disulphide in DMF yields thiazolo[5,4-h]pyridine-2-thione (97), which exists predominantly as this tautomer in neutral media. 2-Chloro-3-isocyanatopyridine reacts with various iV-substituted piperazines to give the... 

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