Bicyclic 5-6 Systems with One Ring Junction Nitrogen Atom: One Extra Heteroatom 1:0

Howard, Arthur S.

doi:10.1016/b978-008096518-5.00177-5

Cited by 11 publications

(5 citation statements)

References 266 publications

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“…This activation can be achieved by transformation into another functional group which is a better building block for the formation of a heterocyclic ring. Such versatile and useful building blocks in heterocyclic chemistry are α-halo ketones and aldehydes since they enable the formation of various heterocyclic systems such as thiazoles [9], indolizines [10], imidazo[1,2-x]azines [11,12], and 1,2,4-triazolo [4,3-x]azines [13,14]. Transformations of (S)-aspartic acid (1) into (S)-3-formylalanine-and (S)-5-bromo-4-oxonorvaline derivatives have been described previously [15][16][17][18][19].…”

Section: May-jun 2002 437mentioning

confidence: 99%

“…N-Acyl-3-(imidazo [1,2-x]azinyl-2)-alanine esters 10a-h were prepared in one step from N-acyl-5-bromo-4-oxonorvaline esters 5 and aminoazines 9a-h. This transformation, which proceeds by initial quarternization followed by condenzation into imidazo-[1,2-x]azinil-2)alanine derivative 10 [11], proved to be useful for the preparation 3-(imidazo[1,2-a]pyridinyl-2)-(10a-e), 3-(imidazo [1,2-b]pyridazinyl-2)-(10f, g), and 3-(imidazo [1,2-a]pyrimidinyl-2)alanine derivatives (10h). Similarly, treatment of 5 with thiobenzamide 11a and thiourea 11b gave the corresponding N-acyl-3-(2-substituted thiazolyl-4)alanine esters 12a, b in 63-81% yields [20,21].…”

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confidence: 99%

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Synthesis of heteroaryl substituted α‐amino acid derivatives, polyols, and related compounds

Svete

2002

Journal of Heterocyclic Chem

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Section: May-jun 2002 437mentioning

confidence: 99%

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confidence: 99%

Synthesis of heteroaryl substituted α‐amino acid derivatives, polyols, and related compounds

Svete

2002

Journal of Heterocyclic Chem

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“…The synthesis of pyrazolo [1,5-a]pyrimidine derivatives have gained significant interest due to their various biological [7][8][9][10][11] and pharmacological activities. Recently, pyrazolo [1,5a]pyrimidines as translocator protein 18 kDa (TSPO) ligands [12] have been studied.…”

Section: Introductionmentioning

confidence: 99%

A three step one-pot regioselective synthesis of highly substituted pyrazolo[1,5-a]pyrimidines assisted by KHSO4 in aqueous media under ultrasound irradiation

2020

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A simple and efficient synthesis of substituted pyrazolo[1,5-a]pyrimidine derivatives has been developed by the use of ultrasound. 5-Methyl-4-phenyl-1H-pyrazol-3-amine required for the synthesis of pyrazolo[1,5-a]pyrimidine derivatives has been easily obtained by the reaction of 3-(dimethylamino)-2-phenylacrylonitrile (formed from readily available 2-phenylacetonitrile) with hydrazine hydrate in refluxing ethanol. The 5-aminopyrazole was then reacted with various formylated active proton compounds in presence of KHSO4 in aqueous medium under ultrasound irradiation to give the desired products. The chemical structures of the newly synthesized compounds were confirmed by IR, 1H NMR, 13C NMR and Mass spectral data. X-ray crystallographic study of a selected compound 6-(4-chlorophenyl)-2-methyl-3-phenylpyrazolo[1,5-a]pyrimidin-7-amine (7c) was performed to ascertain the regioselectivity of the reaction. Crystal data for compound 7c: Triclinic, space group P-1 (no. 2), a = 8.0198(3) Å, b = 14.0341(6) Å, c = 14.2099(6) Å, α = 87.672(2)°, β = 83.902(2)°, γ = 89.120(2)°, V = 1588.87(11) Å3, Z = 4, T = 293(2) K, μ(MoKα) = 0.248 mm-1, Dcalc = 1.400 g/cm3, 12918 reflections measured (4.012° ≤ 2Θ ≤ 49°), 5152 unique (Rint = 0.0411, Rsigma = 0.0429) which were used in all calculations. The final R1 was 0.0486 (I > 2σ(I)) and wR2 was 0.1320 (all data).

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“…In addition, Townsend and Wise reported a book chapter describing the chemistry of oxazolo[5,4‐ b ]pyridine analogues, and this chapter was updated by Buckley in 2008. Furthermore, Howard has published a book chapter describing the chemistry of 5+6 bicyclic heterocycles with a nitrogen atom at the ring junction and described oxazolo[3,2‐ a ]pyridines as an example of this class of compounds.…”

Section: Introduction and Scopementioning

confidence: 99%

Reactivity and stereoselectivity of oxazolopyridines with a ring‐junction nitrogen atom

Monier

Abdel-Latif

El‐Mekabaty

et al. 2019

Journal of Heterocyclic Chem

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The present study demonstrates a synopsis of the scientific researches reported on the different reactions of oxazolo[3,2‐a]pyridines, besides the preparation of significant fused heterocycles up till now. The different main sections that described the reactivity of the inspected analogues include stereoselective alkylation, reactions involved oxazolidine ring, synthesis of polycyclic systems, indole alkaloids, and alkyl amines. The stereochemical selectivity of oxazolopiperidone lactams is studied, in which the configuration of the stereocenter C8a and substituents at the C8 and C8a effect on the stereoselectivity. On the other hand, the synthetic consequence of the alkylation products provides diverse routes for the synthesis of substituted enantiopure piperidines that are used for the synthesis of natural products, for example, (−)‐rhazinilam, (+)‐eburnamonine, (+)‐aspidospermidine, indole alkaloids such as dihydrocleavamine, nor‐20‐epiuleine, (+)‐dasycarpidone, (+)‐uleine, indoloquinolizidine, (+)‐dihydrocorynantheine, (−)‐dihydrocorynantheol, and indolizines, eg, octahydroindolizines, monomorine I, (−)‐S‐coniceine, and (−)‐R‐coniceine.

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Bicyclic 5-6 Systems with One Ring Junction Nitrogen Atom: One Extra Heteroatom 1:0

Cited by 11 publications

References 266 publications

Synthesis of heteroaryl substituted α‐amino acid derivatives, polyols, and related compounds

Synthesis of heteroaryl substituted α‐amino acid derivatives, polyols, and related compounds

A three step one-pot regioselective synthesis of highly substituted pyrazolo[1,5-a]pyrimidines assisted by KHSO4 in aqueous media under ultrasound irradiation

Reactivity and stereoselectivity of oxazolopyridines with a ring‐junction nitrogen atom

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