Synthesis of Various Schiff Bases Containing Isoxazole Ring and Their Applications with Thioglycollic Acid and Diverse Phosphorus Reagents

Abstract

A series of Schiff bases bearing isoxazole and pyrazole rings were synthesized. Application of thioglycollic acid on two selective synthesized Schiff bases afforded the corresponding thiazolidin‐4‐one derivatives. On the other hand, following the multicomponents one‐pot Kabachnik– Fields reaction, the Schiff base generated in situ from 4‐chlorobenzaldehyde and 5‐methyl isoxazol‐3‐amine was trapped by phosphorus reagents to produce the corresponding amino phosphonates in moderate yields. However, the latter products could also be obtained in better yields (≥78%) by directly applying the dialkylphosphites to a selective synthesized Schiff base. Similarly, a series of α‐aminophosphonates could be obtained from 5‐chloro‐3‐methyl‐1H‐pyrazol‐4‐carbaldehyde, 5‐methylisoxazol‐3‐amine, and phosphorus reagents. Moreover, applying hexaalkyl triamido phosphites to the N‐(4‐chlorobenzylidene)‐5‐methylisoxazol‐3‐amine in ethanol afforded methylphosphonic diamide derivatives, whereas N‐((5‐chloro‐3‐methyl‐1H‐pyrazol‐4‐yl)methylene)‐5‐methylisoxazol‐3‐amine underwent dechlorination through reaction with hexaalkyl triamido phosphites to give the respective amine derivatives.

6. Synthesis of α-aminophosphonates by the Kabachnik–Fields reaction and by the Pudovik reaction

“…The synthesis of α-aminophosphonates with an isoxazole ring was accomplished using trialkyl phosphites in the presence of iron(III) chloride in THF ( Figure 6.10) [43].…”

Programmed self-assembly of enzyme activity-inhibited nanomedicine for augmenting chemodynamic tumor nanotherapy

“…TGA is widely utilized as a drug intermediate and detection reagent, but is seldom used for cancer therapy via inhibition of the protein activity. 33,34 Self-assembled materials are ubiquitously found in the natural world and are famous in materials research fields, whether the primary building block arises from molecules or nanoparticles. The vast majority of self-sorting processes are driven by diverse interaction forces (i.e., hydrogen bond, hydrophilic-hydrophobic interactions and DNA base pairing), [35][36][37] which manipulate basic units organized from the molecular level up to the nano-or mesoscopic regions.…”

“…TGA is widely utilized as a drug intermediate and detection reagent, but is seldom used for cancer therapy via inhibition of the protein activity. 33,34…”

Microwave-assisted synthesis of α-aminophosphine oxides by the Kabachnik-Fields reaction applying amides as the starting materials

“…[4][5][6][7] Numerous methods were described for the synthesis of a-aminophosphonates, however, the major part of the protocols reported applied a catalyst. [8][9][10][11][12][13][14][15][16] The senior author of this article, together with a coworker, was who proposed that using the microwave (MW)assisted solvent-free protocol, there is no need for any catalyst. [17] Hence, cost and environmental burdens may be saved.…”