Synthesis and antiviral activity of pyrazolo[3,4-d]-1,3,2-diazaphosphorins

The Reaction of Phosphorus Decasulfide with some Hydrazides and their Hydrazones: New Route for Construction of Four‐membered, Five‐membered, and Six‐membered Phosphorus Heterocycles

“…Compounds 2a – c dissolved readily in aqueous NaOH, acidification surprisingly regenerate 2a – c without removing pyridine. The reaction mechanism was suggested to take place with an initial attack of NH 2 group to P 4 S 10 , followed by attack from thiol to the C═O group to remove water molecule (Scheme ). The IR spectra of compounds 2a – c showed the absorption bands of the NH and P═S groups in the respective regions 3336–3128 cm −1 and 760–741 cm −1 , respectively.…”

“…Phosphorus decasulfide P 4 S 10 (also called phosphorus pentasulfide P 2 S 5 ) is a very important starting material for the synthesis of many linear phosphorus and sulfur compounds but has been used less extensively for the preparation of cyclic compounds containing the exocyclic PS 2 group . Limited heterocyclic compounds containing the exocyclic PS 2 group were prepared by reactions of phosphorus decasulfide with amide systems having reactive group at ortho position such as anthranilamide , 2‐amino‐3‐carbamoyl‐4,5,6,7‐tetrahydrobenzo[ b ]thiophene , N , N ‐diphenylurea , 1,2‐trimethylene‐4‐amino‐5‐cyanoimidazole , 3‐methyl‐4‐carbamoyl‐5‐aminopyrazole , and N ‐[cyano(imidazolidin‐2‐ylidene)methyl]carboxamide . Phosphorus heterocycles are of potential interest as anti‐inflammatory, herbicides, insecticides, and fungicides .…”

Synthesis of new heterocyclic system of 4,5,7,8‐tetrahydroimidazo[1,2‐c][1,3]thiazolo [4,5‐e][1,3,2]diazaphosphinine starting from 2‐aroylamino‐3,3‐dichloroacrylonitrile

“…On reacting with hydrogen sulfide in pyridine, nitriles 2a-c were converted almost quantitatively to corresponding thioamides 3, which were then treated with 2 equiv of P 2 S 5 in pyridine by the known procedure [17][18][19][20] to furnish substituted derivatives 4 of 4,5,7,8-tetrahydroimidazo[1,2c] [1,3]thiazolo [4,5-e] [1,3,2]diazaphosphinine, a novel-fused heterocyclic system. As found, compounds 4 are also obtainable directly from 2 by treating with phosphorus pentasulfide.…”

“…2-Aroylamino-3,3-dichloroacrylonitriles that are readily prepared from easily accessible chloral adducts of carboxamides [1][2][3][4] have been extensively utilized in heterocyclic synthesis [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The present study offers their new application as starting materials to obtain a hitherto unknown heterocyclic system, 4,5,7,8-tetrahydroimidazo [1,2c] [1,3]thiazolo [4,5-e] [1,3,2]diazaphosphinine.…”

Approaches towards the synthesis of 5-aminopyrazoles

“…Nilov et al [ 71 ] have reported that the reaction of α-cyano-β-dimethylaminocrotonamide ( 103 ) with hydrazine hydrate yields 5-amino-3-methylpyrazole-4-carboxamide ( 104 ). The reaction proceeds by loss of dimethylamine in first step followed by cyclization via nucleophilic attack on cyano group ( Scheme 29 ).…”