DRY MEDIA SYNTHESIS OF 4<i>H</i>-1, 4-BENZOTHIAZINES UNDER MICROWAVE IRRADIATION USING BASIC ALUMINA AS SOLID SUPPORT

Paul, Satya; Gupta, Rajive; Loupy, André; Rani, Babita; Dandia, Anshu

doi:10.1081/scc-100103260

Cited by 14 publications

(3 citation statements)

References 21 publications

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“…The vinylogous amide 4 could be obtained by condensation of but-3-enyl amine with acid 3 by refluxing in benzene for 4 h in a Dean−Stark apparatus. Acid-promoted aminodehydroxylation and the application of microwave irradiation led to more rapid transformations, but the product yields were lower. The necessity of a protecting group for the tether nitrogen atom in 4 was deduced from previous experience with photocycloaddition products of N -unprotected tetronic acid amides, which proved to be unstable and reacted further in a retro-Mannich reaction. , The choice of protecting group was guided by previous experience in our group. , Alkoxycarbonyl protecting groups such as N-tert -butyloxycarbonyl had turned out to be an excellent choice to allow for the otherwise impossible [2+2]-photocycloaddition reaction of enamines (λ = 300−350 nm) …”

Section: Resultsmentioning

confidence: 99%

Preparation and Intramolecular [2+2]-Photocycloaddition of 1,5-Dihydropyrrol-2-ones and 5,6-Dihydro-1H-pyridin-2-ones with C-, N-, and O-linked Alkenyl Side Chains at the 4-Position

2008

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The 1,5-dihydropyrrol-2-ones 2, 6, 9, and 11 were prepared from methyl tetramates (1a-c), N-Boc-protected tetramic acid (3), or N-Boc-protected tetramic acid bromide (7) in short reaction sequences and in very good overall yields. The homologous 5,6-dihydro-1H-pyridin-2-ones 16, 18, 20, 21, 23, and 27 were prepared along analogous routes starting from piperidin-2,4-dione (19) or from its N-tert-butyl derivative 15. Optimized conditions for the [2+2]-photocycloaddition include the use of dichloromethane as the solvent and an irradiation with a mercury low-pressure lamp (lambda = 254 nm). Upon applying these conditions at ambient temperature, the corresponding intramolecular photocycloaddition products 28-37 were obtained in good yields (52-79%) and with perfect diastereoselectivity. The constitution and configuration of the products was elucidated by NMR-spectroscopy. For the O-tethered substrates 2a and 20, a strong decrease of the photocycloaddition rate with temperature was observed. The effect was less pronounced for N- and C-tethered substrates 6, 9, 23, and 27. The use of a chiral complexing agent to achieve enantioselective reactions appears viable. Complexing agent (-)-38, however, is not suited because of its instability at lambda = 254 nm.

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Section: Resultsmentioning

confidence: 99%

Preparation and Intramolecular [2+2]-Photocycloaddition of 1,5-Dihydropyrrol-2-ones and 5,6-Dihydro-1H-pyridin-2-ones with C-, N-, and O-linked Alkenyl Side Chains at the 4-Position

2008

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“…It is also used in medicine as an anabolic agent [7][8]. The active core of cephalosporins, which are among the most extensively used βlactum antibiotics, is the 1,3-thiazine nucleus [9][10]. The potential of thiazine to inhibit the growth of tuberculosis and germs, to deactivate HIV (human immunodeficiency virus) in biological fluid, and to serve as an agonist for cannabinoid receptors is a significant property of the compound [11][12].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Identification of Thiazines-4-on Derived from Sulfamethoxazole, and Testing of Some of Their Antibacterial Properties

Mahdi,

Rasheed

2023

JNMES

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The 2-Amino benzothiazol (A) was prepared by reacting Sulfamethoxazole with potassium thiocyanate in the presence of bromine as a catalyst. The 2-amino benzothiazol (A) was reacted with benzaldehyde derivatives in the presence of glacial acetic acid as a catalyst and ethanol as a solvent to produce the Schiff base derivatives (H1-H3). This method was also used to manufacture the Schiff base derivatives (H4-H6). Preparation of thiazines derived from Schiff base derivatives (H1-H3) with the appropriate solvent. The study evaluated the efficacy of several compounds against four bacterial strains, namely E. coli, Staphylococcus aureus, Streptococcus pyogenes, and Klebsiella pneumonia. The findings indicated that the tested compounds exhibited varying degrees of effectiveness against the bacteria at different concentrations (0.1, 1, and 10 mg/ml), with some demonstrating good to moderate activity. The standard antibiotic, Fluconazole, was also included in the experiment at a concentration of 5 mg/ml for comparison purp.

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“…2,3-Disubstituted-1,4benzothiazines were prepared in high yield (83-96%) by oxidative cyclocondensation of 2-aminobenzenethiols and 1,3-dicarbonyl compounds using a catalytic amount of hydrazine hydrate without solvent in a short reaction time (10 min) [14]. Reactions of 2-aminothiophenols with β-keto esters and β-diketones under microwave irradiation (MWI) using basic alumina as heterogeneous catalyst without solvent afforded 4H-benzo-1,4thiazines in a yield of 69-85% within 6-11 min [15]. Furthermore, baker's yeast as whole-cell biocatalyst catalyzed the reaction of 2-aminothiophenols with 1,3-dicarbonyl compounds in methanol and the corresponding 4H-benzo-1,4-thiazines were prepared in 51-82% yield.…”

Section: Introductionmentioning

confidence: 99%

Derivatives of benzo-1,4-thiazine-3-carboxylic acid and the corresponding amino acid conjugates

Kisszékelyi¹,

Stankovianska²,

Mečiarová³

et al. 2022

Beilstein J. Org. Chem.

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Herein, we present the synthesis and utilization of derivatives of 4H-benzo[b][1,4]thiazine-3-carboxylic acid. These benzothiazine compounds were assembled via the coupling of aminothiols and bromopyruvates. Oxidative dimerization of these starting materials was also observed and the corresponding benzothiazine dimers were isolated. Moreover, the coupling of benzothiazines with amino acids was realized. In doing so, an enantioselective synthesis of the nonproteinogenic amino acid 2-amino-3-propylhexanoic acid was accomplished.

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DRY MEDIA SYNTHESIS OF 4H-1, 4-BENZOTHIAZINES UNDER MICROWAVE IRRADIATION USING BASIC ALUMINA AS SOLID SUPPORT

Cited by 14 publications

References 21 publications

Preparation and Intramolecular [2+2]-Photocycloaddition of 1,5-Dihydropyrrol-2-ones and 5,6-Dihydro-1H-pyridin-2-ones with C-, N-, and O-linked Alkenyl Side Chains at the 4-Position

Preparation and Intramolecular [2+2]-Photocycloaddition of 1,5-Dihydropyrrol-2-ones and 5,6-Dihydro-1H-pyridin-2-ones with C-, N-, and O-linked Alkenyl Side Chains at the 4-Position

Synthesis and Identification of Thiazines-4-on Derived from Sulfamethoxazole, and Testing of Some of Their Antibacterial Properties

Derivatives of benzo-1,4-thiazine-3-carboxylic acid and the corresponding amino acid conjugates

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