Domino Cyclization of 2-Isothiocyanatobenzonitrile with Carboxylic Hydrazides − One-Pot Synthesis of 1,2,4-Triazolo[1,5-c]quinazoline-5(6H)-thiones

Abstract

One-pot reactions between carboxylic hydrazides and 2-isothiocyanatobenzonitrile afforded pharmacologically relevant 1,2,4-triazolo[1,5-c]quinazoline-5(6H)-thiones in good yields. These compounds were transformed into the corresponding

Reactions of Substituted Carbohydrazides with Electron-poor Olefins

“…When carbohydrazides 1a -e were treated with two molar equivalents of tetracyanoethylene (2) served which quickly gives way to brown. After concentration of the mixture to dryness and subjecting the residue to vacuum sublimation to remove any unreacted 2, chromatographic separation of the residue in each case gave three zones, containing diacylhydrazines 4a -e (12 -17 %), 5-amino-1-substituted-1H-pyrazole-3,3,4(2H)-tricarbonitriles 5a -e (54 -59 %) and 1,1,2,2-tetracyanoethane (TCNE-H 2 ) (6, 9 -14 %).…”

“…One-pot reactions between carboxylic hydrazides and 2-isothiocyanatobenzonitrile afford pharmacologically relevant 1,2,4-triazolo [1,5-c]quinazoline-5-thiones [2]. Hydrazide compounds can also be converted to triazole-3-thiols [3], 1,3,4-oxadiazole [4], 1,3,4-oxadiazine [4], pyrazolotriazolopyrimidine [5,6] and pyrazolotriazoloquinoline derivatives [7].…”

“…The reaction of methylhydrazine with tetracyanoethylene (2) has been studied in several laboratories [21 -23]. A mixture of 1-N-and 2-N-methyl 0932-0776 / 08 / 0800-0998 $ 06.00 c 2008 Verlag der Zeitschrift für Naturforschung, Tübingen · http://znaturforsch.com Scheme 1.…”

Chemistry and heterocyclization of carbohydrazides

“…One‐pot reaction between carbohydrazides 1 and 5‐chloro‐2‐isothiocyanatobenzonitrile 133 afforded 1,2,4‐triazolo[1,5‐ c ]quinazoline‐5(6 H )‐thiones 136 , in good yields [95]. …”

Stereoselective synthesis of 4H-3,1-benzothiazines via tandem nucleophilic addition/epoxy ring-opening cyclization reactions of 2-(3-phenyloxiranyl)phenyl isothiocyanates

“…The residue was purified by column chromatography on silica gel (dichloromethane/hexane = 1/4) to yield cis-1 (86 mg, 36% in two steps) and trans-1 (40 mg, 17% in two steps). C,70.87;H,4.67;N. 17.71.…”