Azlactones: Retrospect and Prospect

Mukerjee, A. K.

doi:10.3987/r-1987-04-1077

Cited by 69 publications

(30 citation statements)

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“…Adopting earlier reports [14] for syn thesis of several azlactone derivatives, the latter product was utilized as a pre cursor for preparation of the 2-[p-[4"-substituted 5"-oxo-1", 3"-oxazol-in-2"-yl) phenyl]-5-cyano-4-methyltriazolo [4,5-b] pyrido [1', 2'-a]-benzimidazole derivatives (Va-e) and (VIIa-e).The structure of these products was confirmed by their IR spectra which revealed the absence of any absorption corresponding to the different func tions of hippuric acid moiety, of their precursor IV, and the presence of a new absorption near 1,740-1,735cm -1 which might be attributed to the lactonyl-CO of oxazolone moiety. The presence of only one exchangeable signal near 12.30-11.95ppm in 1 H-NMR spectral patterns of compounds Va-e, attributable to NH proton signal of hydrazone moiety, substantiates the assigned structure for these groups of the prepared dyestuffs.…”

Section: Resultsmentioning

confidence: 92%

Synthetic approaches to some new fluorescent dyestuffs for synthetic polymer fibres

Girges¹,

Hanna²,

Ayyad³

1995

Pigment &Amp; Resin Technology

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Since Victor Meyer's first report on coupling of diazonium salts with activated carbon compounds, a growing interest has appeared in literature for synthesis and use of different isolated and/or fused nitrogen‐containing heterocyclic dyestuffs as fluorescent whitening agents. A technically important class of these products is those embodying pyrido (1,2‐a) benzimidazole residue in their structure. The parent pyrido (1, 2‐a) benzi‐midazole itself has been previously used in the synthesis of a variety of dyes and pigments.

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Section: Resultsmentioning

confidence: 92%

Synthetic approaches to some new fluorescent dyestuffs for synthetic polymer fibres

Girges¹,

Hanna²,

Ayyad³

1995

Pigment &Amp; Resin Technology

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“…Another possibility for the quadratic third-order term in eq. [2] or [3] is that it may represent a r,eaction between 1 and an amine dimer. However, the present results exclude the involvement of such amine dimers in the aminolysis of 1 .…”

Section: Hexane ( a ) And Ethanol (B)mentioning

confidence: 99%

“…[2]. The corresponding values of conreaction kinetics followed the rate equation [3]. stants k2 and k, are given in Table 2.…”

Section: Hexane ( a ) And Ethanol (B)mentioning

confidence: 99%

“…reported more than a century ago (1) and their reactions with various nucleophilic reagents have been extensively studied (2)(3)(4)(5)(6)(7)(8)(9), the kinetics and mechanism of their ring cleavage by nitrogen nucleophiles have received little, if any, attention. Recently, in a study designed to determine the steric effect of remote substituents on peptide bond formation, it was reported that the reaction of (Z)-4-benzylidene-2-phenyl- 5(4H)-oxazolone with benzylamine in acetonitrile followed second-order kinetics (10).…”

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confidence: 99%

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Kinetics and mechanism of aminolysis of (Z)-4-arylidene-2-phenyl-5(4H)oxazolones

AL-KAABI¹,

Shawali²

1992

Can. J. Chem.

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SHARIFA S. ALKAABI and AHMAD S. SHAWALI Can. J. Chem. 70, 2515 (1992). The kinetics of the reactions of a series of (Z)-4-arylidene-2-phenyl-5(4H)oxazolones 1 with n-butylamine and piperidine were studied spectrophotometrically in dioxane, ethanol, and cyclohexane under pseudo-first-order conditions and at different temperatures. The relation k,(obs) = kz[amine] + k3[aminelZ was found applicable for all reactions studied in either dioxane or ethanol. However, in cyclohexane the n-butylaminolysis of 1 followed only third-order kinetics k,(obs) = k 3 [ n -~u~~, l Z .The kinetics of the reaction of 1 with n-butylamine in the presence of catalytic amounts of tri-. The rate constants kZ and k3 correlated well with the Hammett equation and the corresponding activation parameters were determined. The results were interpreted in terms of a mechanism involving solvent-and amine-catalyzed processes. Recently, in a study designed to determine the steric effect of remote substituents on peptide bond formation, it was reported that the reaction of (Z)-4-benzylidene-2-phenyl-5(4H)-oxazolone with benzylamine in acetonitrile followed second-order kinetics (10). This result seems surprising since the reaction of compounds 1, being cyclic esters, with nitrogen nucleophiles in aprotic solvent would be expected to exhibit a kinetic pattern similar to that reported for aminolysis of acyclic esters. Extensive kinetic studies, in our laboratory and others, on the aminolysis of acyclic esters in aprotic solvents established that such reactions are subject to general base catalysis (1 1-23). Thus, under pseudo-firstorder conditions the reactions of esters with primary amine (A) and in the presence of a tertiary amine (B) were found to follow the rate law: k,(obs.In a few cases the kZ term was not observed (16,21,22). Since compounds 1 are versatile intermediates in the syntheses of peptides and didehydroamino acids (24), it was thought important to investigate in some detail the kinetics of their aminolysis to shed light on the mechanism of their ring cleavage by amines in both aprotic and protic solvents. For this purpose we studied the kinetics of the reactions of a series of (Z)-4-arylidene-2-phenyl-5-(4H)-oxazolones lai with 11-butylamine in dioxane, ethanol, and cyclohexane at '~u t h o r to whom correspondence may be addressed. Present address: Department of Chemistry, Faculty of Science, University of Cairo, Giza, Egypt. different temperatures under pseudo-first-order conditions. The other objective of the present study was to determine both solvent and substituent effects on the aminolytic reactivity of 1.Results and discussion (Z)-4-Arylidene-2-phenyl-5(4H)-oxazolones In-i were prepared from hippuric acid and the appropriate substituted benzaldehyde in the presence of acetic anhydride and anhydrous sodium acetate according to the Erlenmeyer method (25). The Z configuration indicated was based on the fact that the latter method of synthesis of 1 was reported to give the thermodynamically more stable Z isomer (6,(26)(27)(28). The...

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“…For this purpose, several combinations of solvents (THF, MeCN, 1,2-dimethoxyethane) and bases (NaH [15] …”

Section: Tbdms = (T-bu)mesimentioning

confidence: 99%

Stereoselective Syntheses of Tetrahydroesterastin‐β ‐Lactam Analogues

Huber

Schneider

1994

Helvetica Chimica Acta

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Azlactones: Retrospect and Prospect

Cited by 69 publications

References 0 publications

Synthetic approaches to some new fluorescent dyestuffs for synthetic polymer fibres

Synthetic approaches to some new fluorescent dyestuffs for synthetic polymer fibres

Kinetics and mechanism of aminolysis of (Z)-4-arylidene-2-phenyl-5(4H)oxazolones

Stereoselective Syntheses of Tetrahydroesterastin‐β ‐Lactam Analogues

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