A Facile Synthesis of 5,6-Dihydro-4H-pyrrolo[3,4-d]thiazole and Other Pyrrolidine-Fused Aromatic Ring Systems via One-Step Cyclization from Diols

Yoshikawa, Kunihiko; Nagata, Tsutomu; Yoshino, Teruo; Haginoya, Noriyasu; Muto, Ryo; Mochizuki, Akiyoshi; Ohta, Toshiharu

doi:10.3987/com-12-12481

Cited by 4 publications

(1 citation statement)

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“…Derivatives of 2‐pyrazolin‐5‐one are found to show remarkable anti‐tubercular , antimicrobial , and anti‐inflammatory activities. On the other hand, the chemistry of thiazoles has received considerable attention in recent years owing to their synthetic and biological importance. Among the analogs, pyrazoline compound; A and thiazole derivative especially BILS 179BS; B were reported to exhibit a high antiviral activity against hepatitis A virus and hepatitis B virus HSV, respectively.…”

Section: Introductionmentioning

confidence: 99%

2‐Pyrazolin‐5‐One‐Based Heterocycles: Synthesis and Characterization

Abeed

2014

Journal of Heterocyclic Chem

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A novel series of pyrazoline and thiazole derivatives incorporating 2-pyrazolin-5-one moiety were synthesized starting from α,β-unsaturated ketones under the effect of hydrazine derivatives and thiosemicarbazide. The obtained pyrazolines 4a,b were treated with different reagents to afford N-substituted pyrazolines 5a,b-8a,b. N-Thiocarbamoyl pyrazolines 12a,b were cyclized using phenacyl bromide, 2,3-dichloroquinoxaline, and monochloroacetic acid afforded the novel pyrazolinyl thiazoles 13a,b-16a-f. The newly synthesized compounds were characterized by analytical and spectral data.J. Heterocyclic Chem., 00, 00 (2014).© 2014 HeteroCorporation pyrazolines 3a,b were formed. The presence of N-acetyl group was established using IR and 1 H-NMR spectra. While condensing 1a,b with hydrazine hydrate in ethanol, 3-(3methyl-5-oxo-1-phenyl-2-pyrazolin-4-yl)-5-aryl-2-pyrazolines 4a,b were obtained. The reaction includes formation of hydrazones intermediate and then addition of NH 2 of hydrazones to the double bond. Upon acetylation of the pyrazolines 4a,b by acetic acid, N-acetyl pyrazolines 3a,b were obtained. Moreover, the aforementioned pyrazoline derivatives 4a,b were converted into the corresponding substituted N-pyrazolines 5a,b-8a,b through their reaction with various reagents such as chloroacetyl chloride, phenyl isothiocyanate, benzenesulfonyl chloride, and benzoyl chloride, respectively.The structures of products 5a,b-8a,b were evidenced by their spectra (IR, 1 H-NMR, 13 C-NMR, and MS) and elemental analyses (see Experimental section and Table 1).N-phenyl pyrazolines 9a,b were obtained upon condensing with phenyl hydrazine in hot ethanol. The presence of N-phenyl group in 9a or 9b was elucidated from spectral data and EIMS, which is in agreement with their molecular weights. The isooxazoline derivatives 10a,b were obtained through condensation of 1a,b with hydroxyl amine in hot ethanol containing anhydrous sodium acetate. The spectroscopic data and elemental analysis were constituent with the structures of compounds 10a,b.On the other hand, binucleophile compound like ophenylenediamine was condensed with 1a,b in ethanol Scheme 1. Reagents: (i) NH 2 NH 2 .H 2 O/HCOOH; (ii) NH 2 NH 2 .H 2 O/AcOH; (iii) NH 2 NH 2 .H 2 O/EtOH; (iv) AcOH; (v) ClCH 2 COCl/toluene; (vi) PhNCS/ EtOH; (vii) PhSO 2 Cl/pyridine; (viii) PhCOCl/pyridine; (ix) PhNHNH 2 /EtOH; (x) NH 2 OH.HCl/EtOH, AcONa; (xi) o-phenylenediamine/EtOH.Scheme 2. Reagents: (i) NH 2 CSNHNH 2 /EtOH, NaOH; (ii) PhCOCH 2 Br/EtOH; (iii) 2,3-dichloroquinoxaline/EtOH; (iv) ClCH 2 COOH/AcOH, AcONa;(v) ArCHO/AcOH, AcONa; (vi) ClCH 2 COOH, ArCHO/AcOH, AcONa.Month 2014 2-Pyrazolin-5-One-

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Section: Introductionmentioning

confidence: 99%

2‐Pyrazolin‐5‐One‐Based Heterocycles: Synthesis and Characterization

Abeed

2014

Journal of Heterocyclic Chem

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Nonclassical Mechanism in the Cyclodehydration of Diols Catalyzed by a Bifunctional Iridium Complex

Miera

Bermejo‐López

Martínez‐Castro

et al. 2019

Chemistry A European J

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1,4‐ and 1,5‐diols undergo cyclodehydration upon treatment with cationic N‐heterocyclic carbene (NHC)–IrIII complexes to give tetrahydrofurans and tetrahydropyrans, respectively. The mechanism was investigated, and a metal‐hydride‐driven pathway was proposed for all substrates, except for very electron‐rich ones. This contrasts with the well‐established classical pathways that involve nucleophilic substitution.

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