A novel synthesis of heterocycles from thiocarbohydrazides

Current methods for the synthesis of 2-substituted azoles

“…246 Mourad et al have investigated the reaction of a variety of 2-amino-1,3-azoles with activated quinones, giving products such as 274 in good yields (Scheme 124). 247,248 Imidazo[1,2-b]thiazolines 249 undergo nucleophilic displacement with allylic and benzylic Grignard reagents (Scheme 125); alkyl Grignard and alkyl or aryl lithium reagents result in nucleophilic attack on sulfur and loss of ethylene to furnish 2-thioalkyl-1H-imidazoles. The authors note the relief of ring strain via loss of ethylene to be a driving force in the latter cases.…”

Indazole derivatives from substituted ylidene-N-phenylhydrazinecarbothioamides and benzo- as well as naphthoquinones

“…[1][2][3][4][5][6] Several oxidizing agents can be used for the cyclization of semi-and thiosemicarbazones and it has been investigated how the oxidant as well as the structure of the open chain molecules can affect regiochemistry and yield of the process. 1,7-9 2,3,5,6-Tetrachloro-1,4-benzoquinone (CHL-p, 10) and 2,3-dichloro-1,4-naphthoquinone (14) undergo nucleophilic substitution of one or two chlorine atoms by thioacetamide, [10][11][12] thiourea, 13,14 substituted thiourea, 15 thiocarbazones, 16 hydrazine-1,2-dicarbothioamides, 17 thiosemicarbazides, 18 and thiosemicarbazones. 4 On the other hand, the synthesis of indazole derivatives from the reaction of diazoalkanes with some benzo-and naphthoquinones has been extensively investigated.…”

Nucleophilic reactions of 1-substituted-2,5-dithiobiureas with chlorinated benzo- and naphthoquinones as well as (1,3-dioxo-2,3-dihydro-1(H)-inden-2-ylidene)propanedinitrile

“…3 Also, the heterocyclization of compounds having an extended urea like chain such as 1,4-and 2,4-disubstituted thiosemicarbazides have been reported. 4,5 2,3,5,6-Tetrachloro-1,4-benzoquinone (2a) and 2,3-dichloro-1,4-naphthoquinone (7) undergo nucleophilic substitution of one or two chlorine atoms by thioacetamide or thiourea, [6][7][8][9] thiocarbohydrazide, 10 thiocarbazones, 10 Nsubstituted thioureas, 11 disubstituted-2,5-dithiobiureas, 12 thiosemicarbazones, 13 and substituted thiosemicarbazides. 14 A large variety of quinones including heterocyclic rings, have been used as synthetic intermediates and in the medicinal, [15][16][17][18] as well as dye chemistry.…”