Synthesis and Spectral Characterization of Some Novel Phosphonyl‐ and Phosphoryl Pyrazole Compounds

Abstract

1,3-Diphenyl-1H-pyrazole-4-carbal dehyde (1) reacted with aniline, 2-substituted anilines, and P,P-dimethylphosphinic hydrazide in the presence of diethyl phosphite to give acyclic α-aminophosphonate 2, cyclic α-aminophosphonates 4-6, and α-hydrazinophosphonate 7, respectively. Also, treatment of aldehyde 1 with cyanoacetohydrazide, acetophenone, and malononitrile afforded the condensation products 8, 16, and 21, respectively, which in turn, reacted with diethyl phosphite and P,P-dimethylphosphinic hydrazide. The reaction of diethyl phosphite with the hydrazone 8 and chalcone 16 yielded the novel phosphorus heterocycles 13 and 18, respectively, while its reaction with the dicyanoarylidene 21 produced the dicyanopyrazolyl phosphonate 22. On the other hand, treatment of the hydrazone 8 with P,P-dimethylphosphinic hydrazide gave the unexpected P,P-dimethylphosphinic hydrazone 15, which reacted with diethyl phosphite forming α-hydrazinophosphonate 7. Furthermore, the interesting N-phosphoryl pyrazoles 20 and 24 were resulted in good yield via cycloaddition of P,P-dimethylphosphinic hydrazide to the chalcone 16 and dicyanoarylidene 21, respectively. Structures of all newly synthesized compounds were confirmed by considering the data of IR spectroscopy, MS, and

Fifty Years of (Benz)oxaphospholene Chemistry

“…In almost the same way,t hiocarbonyl compounds gave rise to oxaphospholenes in ar eactionw ith trimethylsilyl dimethyl phosphite. [43] As part of as creening on antioxidanta ctivity of S-and Ncontaining spirocycles, one tetracyclic structure 80 containing an oxaphospholene moiety was obtainedi nat hree-step sequence( Scheme 16). Using dioxaphosphorinone 69 as an ucleophile allowed the synthesis of a3 ,5-disubstituted oxaphospholene 70 (Scheme 13).…”

“…[42] Quite recently,a ne xample of an oxaphospholene carrying a 4-pyrazolyl substituent was reported, resulting from the 1,4-addition of diethyl phosphite to enone 73 (Scheme 15). [43] As part of as creening on antioxidanta ctivity of S-and Ncontaining spirocycles, one tetracyclic structure 80 containing an oxaphospholene moiety was obtainedi nat hree-step sequence( Scheme 16). [44] Spirocyclic tricycle 78,w hich was obtained by condensation of indoline-2,3-dione 75 with p-fluoro aniline 76 and 2-mercaptoacetic acid 77,w as transformed into enone 79 via aK noevenagel-type condensation.…”

Recent advances in Michael addition of H-phosphonates

“…Recently, one-pot synthetic approach to the novel phosphorus heterocycles was reported. 74 The reaction of diethylphosphonate with chalcone 23 yielded phospha-Michael adduct 24a which further underwent intramolecular cyclization under the same reaction conditions via tautomeric form 24b. As a result, the oxaphospholylpyrazole 25 was isolated as a sole product.…”

Methods for synthesis of N-heterocyclyl/heteroaryl- α-aminophosphonates and α-(azaheterocyclyl)phosphonates

“…24 In continuation of our work on the preparation of α-aminophosphonates containing heterocyclic systems, [25][26][27][28][29][30] we report in this review article all the available synthetic methods for synthesis of N-heterocyclyl/heteroaryl-α-aminophosphonates (Type A) and α-(azaheterocyclyl)phosphonates (Type B) (Figure 1). …”