The Preparation of Substituted 5H-Pyrazolo[1,5-c] [1,3]-Benzoxazin-5-ones from the Trianions of Certain Hydroxyphenylcarboethoxyhydrazones

Mazat, C. L.; Beam, Charles F.; Hines, Margaret A.

doi:10.1080/00397919008052291

Cited by 18 publications

(4 citation statements)

References 7 publications

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“…Recently, Langer and coworkers reported an efficient method for the synthesis of pyrazole-3-carboxylates 28a 29 The cyclic products 65 were formed after treatment of the reaction mixture with acid (Scheme 15, Table 9). …”

Section: Scheme 12 Synthesis Of Functionalized Pyrazolesmentioning

confidence: 99%

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Synthesis of Functionalized Heterocycles by Cyclization Reactions of Oxime and Hydrazone 1,4-Dianions

Dang¹,

Dang²,

Langer³

2011

Synlett

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Oxime and hydrazone 1,4-dianions can be generated in situ by deprotonation with 2 equivalents of n-butyllithium (n-BuLi) or lithium diisopropylamide (LDA). In this account, the development and synthetic applications of one-pot cyclizations of oxime and hydrazone dianions with various electrophiles are highlighted. These reactions provide an efficient synthesis of functionalized isoxazoles, pyrazoles and other heterocycles.

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Section: Scheme 12 Synthesis Of Functionalized Pyrazolesmentioning

confidence: 99%

“…Beam et al also developed an interesting method for the synthesis of substituted pyrazolobenzoxazinones 65 by cyclocondensation of hydrazones 53 with lithiated methyl salicylate 64. 29 The cyclic products 65 were formed after treatment of the reaction mixture with acid (Scheme 15, Table 9).…”

Section: Scheme 12 Synthesis Of Functionalized Pyrazolesmentioning

confidence: 99%

Synthesis of Functionalized Heterocycles by Cyclization Reactions of Oxime and Hydrazone 1,4-Dianions

Dang¹,

Dang²,

Langer³

2011

Synlett

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“…These electrophilic reagents presented a challenge because of the potential for diminished electrophilicity and reactivity of the carboxyl carbon, which is in a resonance position relative to the phenoxide ion portion of the electrophilic substrate (17)(18)(19). The condensation-cyclization of these trianion-type intermediates with lithiated methyl thiosalicylate (20) was not attempted at that time, and such an investigation offered the potential for the preparation of thiochromone-2-acetamides (N-aryl-4-oxo-4H-1-benzothiopyran-2-acetamides) that may be difficult to prepare by traditional procedures.…”

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confidence: 99%

Preparation of N-aryl-4-oxo-4H-1-benzothiopyran-2-acetamides from trilithiated acetoacetanilides and lithiated methyl thiosalicylate

Angel¹,

Finefrock²,

French³

et al. 1999

Can. J. Chem.

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Acetoacetanilide and substituted acetoacetanilides were trilithiated in excess lithium diisopropylamide, and the polylithiated intermediates were regioselectively condensed with lithiated methyl thiosalicylate, followed by acid cyclization to afford substituted N-aryl-4-oxo-4H-1-benzothiopyran-2-acetamides (thiochromone-2-acetamides).Résumé : On a effectué une trilithiation de l'acétoacétanilide et d'acétoacétanilides substitués en procédant dans un excès de diisopropylamidure de lithium, et les intermédiaires polylithiés ont subi une condensation régiosélective par réaction avec du thiosalicylate de méthyle lithié, suivie d'une cyclisation acide conduisant à des N-aryl-4-oxo-4H-1-benzothiopyran-2-acétamides (thiochromon-2-acétamides).Mots clés : thiochromones; synthèse, base forte anion multiple; condensation du type de Claisen.

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“…One of our major strong-base multiple anion synthesis efforts has dealt with the preparation of 1H-pyrazoles and related compounds by the utilization of C(α), N-hydrazone (e.g., phenyl, benzoyl, carboalkoxy, etc.) entry compounds that were polylithiated with excess lithium diisopropylamide [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. The polylithiated intermediates were condensed with a variety of esters and other electrophilic reagents, followed by an acid cyclization of C-acylated intermediates that were not usually isolated.…”

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confidence: 99%

Preparation of substituted 1,2‐Dihydro‐3H‐pyrazol‐3‐ones from polylithiated 2′‐phenylphenylacetohydrazides and aromatic esters

Downs

Pastine

Townsend

et al. 2001

Journal of Heterocyclic Chem

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Several 2'-phenylphenylacetohydrazides were polylithiated with excess lithium diisopropylamide, and the resulting intermediates were condensed with several aromatic esters to afford C-acylated intermediates that were not usually isolated, but acid cyclized directly to 1,4,5-trisubstituted, 1,2-dihydro-3H-pyrazol-3-ones.J. Heterocyclic Chem., 38, 695 (2001).While the preparations, reactions, and uses of 1H-pyrazoles and related heterocyclic compounds are well documented [1], investigations involving other pyrazole compounds such as 1,2-dihydro-3H-pyrazol-3-ones [2,3] have received less investigative attention. For example, a key compound to this report, 1,2-dihydro-1,4,5-triphenyl-3H-pyrazol-3-one 4, has been prepared by: (1) the fusion of 2'-phenylacetohydrazine with ethyl 2-benzoyl-2-phenylacetate [4]; or (2) by the condensation of benzoylphenyl ketene with phenylhydrazine [5]; or (3) by the reaction of diphenylcyclopropenone with excess phenylhydrazine [6]. Several additional and related alkyl, or alkyl-aryl, 1,4,5-trisubstituted, 1,2-dihydro-3H-pyrazol-3-ones have also been prepared and studied, especially with regard to their biological-health applications or use in other syntheses [7][8][9][10][11][12][13][14][15]. There is a preference to listing the structures for these molecules as 1,2-dihydro-3H-pyrazol-3-ones instead of their tautomers, 3-hydroxy-1H-pyrazoles. Both forms have been reported by investigators [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], which may indicate the differences that exist when the supporting structural data was obtained from a solution, a mull, or a crystalline form of a particular compound.Compound 1, 2'-phenylphenylacetohydrazide, a key starting material used during this study, has been used for the preparation of other pyrazole or pyrazole-related heterocyclic compounds such as methods involving variously substituted N-methyl or N-acylphenylacetohydrazides, or a condensation-cyclization of a probable carbanion resulting from deprotonation with calcium hydride followed by the addition of N, N-dimethylformamide [20-25].In recent investigations with other carbohydrazides, we polylithiated o-toluoylcarboalkoxyhydrazides (2'-(2-methylbenzoyl)hydrazinocarboxylic acid esters) with excess lithium diisopropylamide, and condensed-cyclized the polylithiated intermediates with a variety of aromatic esters. This was followed by acid cyclization of the C-acylated intermediates to afford isocarbostyrils (1(2H)-isoquinolinones) [26].One of our major strong-base multiple anion synthesis efforts has dealt with the preparation of 1H-pyrazoles and related compounds by the utilization of C(α), N-hydrazone (e.g., phenyl, benzoyl, carboalkoxy, etc.) entry compounds that were polylithiated with excess lithium diisopropylamide [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. The polylithiated intermediates were condensed with a variety of esters and other electrophilic reagents, followed by an acid cyclization of C-acylated intermediates that were not usually isolated. This...

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The Preparation of Substituted 5H-Pyrazolo[1,5-c] [1,3]-Benzoxazin-5-ones from the Trianions of Certain Hydroxyphenylcarboethoxyhydrazones

Cited by 18 publications

References 7 publications

Synthesis of Functionalized Heterocycles by Cyclization Reactions of Oxime and Hydrazone 1,4-Dianions

Synthesis of Functionalized Heterocycles by Cyclization Reactions of Oxime and Hydrazone 1,4-Dianions

Preparation of N-aryl-4-oxo-4H-1-benzothiopyran-2-acetamides from trilithiated acetoacetanilides and lithiated methyl thiosalicylate

Preparation of substituted 1,2‐Dihydro‐3H‐pyrazol‐3‐ones from polylithiated 2′‐phenylphenylacetohydrazides and aromatic esters

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