Thiophenes and phenylacetylenes, decorated with 1-methylindol-2-yl, 1,3,2-benzodiazaborol-2-yl, 1,3,2-diazaborol-2-yl, or 1,3,2-diazaborolidinyl groups at one end and dimesitylborolyl or CN substituents at the opposite end of the molecules, were synthesized. Upon UV irradiation, these push-pull systems in THF solution gave rise to bright-blue emission with Stokes shifts ranging from 4100 to 9300 cm–1 and quantum efficiencies up to 0.99. Thereby intramolecular charge transfer took place from the HOMO of the indolyl or borolyl fluorophores to the LUMO, mainly centered on the electron-withdrawing cyano or dimesitylboranyl group.
A series of novel isatin‐coumarin derivatives tethered through ethylene were designed, synthesized, and evaluated for their in vitro antimycobacterial activities against Mycobacterium tuberculosis (MTB) H37Rv and multidrug‐resistant tuberculosis (MDR‐TB). All hybrids exhibited potential antimycobacterial activities against MTB H37Rv and MDR‐TB with minimum inhibitory concentration (MIC) ranging from 32 to 256?μg/mL. In particular, the hybrid 4h (MIC: 50 and 32?μg/mL) was most active against MTB H 37 Rv and MDR‐TB strains, which was 2 and >4 folds more potent than the first‐line antitubercular agents rifampicin (MIC: 64?μg/mL) and isoniazid (MIC: >128?μg/mL) against MDR‐TB, warrant further optimization.
1,3,4‐Oxadiazine derivatives were prepared via green and more sustainable procedure employing Grinding Chemistry. The green context of the procedure was evaluated by comparing its components with that of the conventional one. The antibacterial and antifungal activities of all the synthesized compounds were evaluated against some bacterial and fungal strains and showed promising results. The structures of the resulted compounds were identified and confirmed by elemental analysis and mass, 1 H‐NMR, and 13 C‐NMR spectroscopies.
Biscoumarin analogs were synthesized by the reaction between two equivalent of 4‐hydroxycoumarin and one equivalent of aryl aldehydes induced by visible light 22?W compact fluorescent lamp (CFL) bulb]. This new method is simple, cost‐effective, and furnished excellent yields with broad substrate generality in short reaction time.
Syntheses of pyridazine and pyrrole analogues of 2‐aminotetralin starting from 3‐cyclohexene‐1‐carboxylic acid are reported. All syntheses involve the following key steps: Curtius rearrangement for amine functionality, inverse electron demand Diels–Alder addition with 1,2,4,5‐tetrazine for pyridazine ring synthesis, and pyridazine‐to‐pyrrole ring contraction for pyrrole ring formation.
A convenient eco‐friendly one‐pot synthesis of 14‐aryl‐14 H ‐dibenzo a, j] xanthenes were developed by the condensation of aromatic aldehydes and β ‐naphthol with BTADCI (Benzyltrimethylammonium dichloroiodate) as catalyst under solvent free conditions and microwave irradiation with much more rate accelerations and afford very good yields. Developed protocols involve mild reaction conditions, simple isolation of derivatives with inexpensive reagents.
Pyrrol‐3‐yl squaraine dyes are prepared by the condensation of 3,4‐dihydroxycyclobut‐3‐ene‐1,2‐dione with two‐molar equivalence of a 2,5‐disubstituted pyrrole possessing a free β‐position, or substituted indoles with a similarly free β‐position. From the first reported syntheses of two indol‐3‐yl squaraines in 1966, numerous pyrrol‐3‐yl squaraines (including indol‐3‐yl squaraines) have been reported in both the scientific and patent literatures. This microreview highlights the synthesis, history, spectroscopy, and applications of pyrrol‐3‐yl squaraines from their first preparation to the present date.
A series of newly synthesized compounds of quinazolinone by various substituents was screened for its pharmacological activities. These included their action as antibacterial agents against pathogenic bacteria ( Staphylococcus aureus , Streptococcus pneumoniae , Escherichia coli , Klebsiella pneumoniae , and Pseudomonas aeruginosa ) and as antifungal agents against Aspergillus niger and pathogenic yeast ( Candida albicans ). The presently investigated compounds were synthesized in higher yields, and the structure features were elucidated on the basis of IR, 1 H‐NMR, and mass and elemental analysis data. These compounds were also evaluated as antioxidant agent. The results revealed that six compounds ( 2a , 11b , 11a , 2b , 13a , and 3c ) exhibited higher antimicrobial activity against the tested pathogenic strains. In addition, it was found that compound 6a exhibited a radical scavenging activity higher than other studied compounds.
The bicyclic pyran thiolone tetrahydro-3αH-1,3]dithiolo4,5-β]pyran-2-thione (3a) engages in a highly unusual fragmentation in the presence of DDQ. The pyran thiolone,3a, was synthesized by chlorination of 3,4-dihydro-2H-pyran (1), followed by condensing with CS2and NaSH. Reaction of3awith DDQ generates the isomerized pyran thiolone tetrahydro-3αH-1,3]dithiolo4,5-β]pyran-2-thione (3b) and 4-benzyl-5-(3-hydroxypropyl)-1,3-dithiole-2-thione (4) via a deep-seated rearrangement. The identity of3bwas confirmed by single crystal X-ray analysis: P21/c, a=5.807(9) ?, b = 12.99(2) ?, c = 11.445(15), β=113.23(6)°. Mechanistic experiments and computational insight is used to explain the likely sequence of events in the highly unusual formation of4. Collectively, these results establish fundamental reactivity patterns for further research in this area.
A series of novel 6-aryl-3-(1,2,3,4-tetrahydroxybutanol-1-yl)-7H-1,2,4-triazolo3,4-b]1,3 ,4]thiadiazines were easily synthesized in high yields by means of the reactions of 4-amino-5-(1,2,3,4-tetrahydroxybutyl)-2,4-dihydro-3H-1,2,4-triazole-3-th ione (1) with substituted omega-bromoacetophenones or omega-chloroacetophenone. Nearly all of the title compounds possess plant growth-promoting activities.
Novel microbiocides 2-(hydroxymethyl)benzod)isothiazol-3(2H)-one (7) and (3-oxobenzod]isothiazol-2(3H)-yl)methyl benzencarboxylates (11a-c) were synthesized in good yields, and their structures were characterized by means of H-1 NMR, MS, and elemental analysis. The new compounds were tested preliminarily in laboratory assays against the aquicolous bacteria including Escherichia coli, Staphyloccus aurueus, Vibrio alginolyticus, Aeromonas hydrophila, and Bacillus subtilis. The results show all the synthesized compounds have good antimicrobial activity. The antimicrobial activity of all the tested compounds against all test bacteria is >96.6% at the concentration of 10(-2) mg mL(-1). These compounds can be further developed for effective microbiocides in the future.
This communication reports on the investigation of a new recyclization conversion of a pyrimidine ring, which can be referred to as C-C recyclization. In this reaction the nucleophile cleaves the pyrimidine ring at the N(3)-C(4) bond, and following rotation around the single C(5)-C(6) bond the new cyclization takes place. This type of recyclization has general applicability, and takes place upon alkali treatment of substituted 4-methyl-5-ethoxycarbonyl- and 4-amino-5-ethoxycarbonyl-pyrimidines (1) which are transformed respectively to 4-hydroxy-5-acetyl- and 4-hydroxy-5-carbamoylpyrimidines (2). The obtained pyrimidyl-ketones can be readily converted to their hydrazones7–12.