Reaction of 4-arylidene-3-methyl-1-phenyl-5-pyrazolones with amines

Reactions of 2‐amino‐3‐cyano‐4,5,6,7‐tetrahydrobenzo[b]thiophene and 2‐amino‐3‐cyano‐4,7‐diphenyl‐5‐methyl‐4H‐pyrano[2,3‐c] pyrazole with phenylisocyanate, carbon disulfide, and thiourea

“…A base catalyzed pyrano ring opening (route b) gave (D) and the benzylidenepyrazolone (A). (A) undergoes benzylidene elimination [6] to give 8 that was detected by TLC in the reaction mixture. Compound (D) condenses with benzaldehyde to give (E) which either oxidizes to give compound 9 or hydrolyzes followed by oxidation and addition of 2 moles of ethanol to give compound 11.…”

“…Benzylidenepyrazolone (A) undergoes benzylidene elimination [6] to give benzaldehyde and pyrazolinone that attacks another molecule of (A) to give 8. On the other hand, cyanoacetamide (B) adds to carbon disulfide to give the intermediate (C) (not isolated) that either dimerizes to give 6 or attacks another molecule of 2a to afford 7 as outlined (Scheme 3).…”

“…1 H-and 13 C-NMR spectra were measured in DMSO-d 6 or CDCl 3 on a Varian Gemini instrument at 200 and 50 MHz, respectively; in both cases, chemical shifts were given in ppm downfield from internal TMS. Mass spectra were recorded on a Shimadzu GC-MS QP 1000 EX instrument operating at 70 eV.…”

Chemistry of 4,4′‐(arylmethylene)‐bis(3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐ol)s

“…Treatment of substituted arylidene pyrazolone 128 with isobutylamine 129 in benzene afforded the salt 130 which dissolved in NaOH and then neutralized with HCl to give the adducts 131 (Scheme ).…”