N,N’-dimethyl formamide (DMF) mediated Vilsmeier–Haack adducts with 1,3,5-triazine compounds as efficient catalysts for the transesterification of β-ketoesters

Abstract

N, N’-dimethyl formamide (DMF) mediated Vilsmeier–Haack (VH) adducts with 1,3,5-triazine compunds such as trichloroisocyanuric acid (TCCA) and trichlorotriazine (TCTA) were prepared by replacing classical oxy chlorides POCl₃, and SOCl₂, which were explored as efficient catalysts for the transesterification of β-ketoesters. The prepared (TCCA/DMF) and (TCTA/DMF) adducts improved greenery of the classical Vilsmeier–Haack reagents (POCl₃/DMF), and (SOCl₂/DMF), and demonstrated their better efficient catalytic ativity. Reaction times were in the range: 3.5 to 6.5?hr (SOCl₂/DMF); 2.8–5.2?hr (POCl₃/DMF); 2.5–5.2?hr (TCCA/DMF) and 2.5–5.0?hr (TCTA/DMF) catalytic systems. Ultrasonically (US) assisted protocols with these reagents further reduced the reaction times (two to three times), while microwave assisted (MW) protocols with these reagents were much more effective. The reactions could be completed in only few seconds (less than a minute) in MWassisted protocols as compared to US assited reactions, followed by good product yields.     

Asymmetric Synthesis of Unnatural Amino Acids and Tamsulosin Chiral Intermediate

An efficient and enantioselective hydrogenation of N-acetylamino phenyl acrylic acids was successfully developed by using ruthenium catalyst. This methodology is important in the field of pharmaceuticals and provides a new process for the preparation of unnatural amino acids and tamsulosin chiral intermediate.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.]     

Determination of salutary parameters to facilitate bio-energy production from three uncommon biomasses using thermogravimetric analysis

Fuels derived from biomass are renewable as well as environment friendly. In this study, three biomasses viz. husk of areca nut (Areca catheu), trunks of moj (Albizzia lucida), and bon bogori (Ziziphus rugosus) available in North-East region of India were tested as potential biofuel sources. The accentuation of this study was to determine the kinetic parameters using thermogravimetric (TG) technique under air and nitrogen atmosphere. The experiments were carried out within temperature range 300–973 K under air and nitrogen atmosphere at four different heating rates viz. 5, 10, 15, and 20 K min^?1, respectively. The mass losses at different lumps in the TG graphs were estimated. The first-order kinetic parameters such as activation energy and pre-exponential factor were calculated for different reaction zones for all the three biomass samples. Effects of atmosphere on combustion characteristics (e.g., peak temperature, ignition temperature, and reactivity index) of biomasses were also determined in this study. Areca nut husk has highest ignition temperature (526.38 K) and reactivity index (0.21) but moj has highest peak temperature (597.91 K) along with highest activation energy (348.04 kJ mol^?1) and pre-exponential factor (1.12 × 10²⁴ min^?1), respectively.     

Microwave assisted synthesis of novel methylenebis{2-[(1-benzyl/cyclohexyl-1H-1,2,3-triazol-4-yl)methoxy]chalcones} and their antibacterial activity

A series of novel methylenebis{2-[(1-benzyl/cyclohexyl-1H-1,2,3-triazol-4-yl)methoxy]chalcones} (IVa-IVn) have been synthesized by the Click reaction and Claisen-Schmidt condensation of 5,5′-methylenebis[2-(prop-2-yn-1-yloxy)benzaldehyde] under microwave irradiation with high yields. All products have been characterized by spectral data including FT-IR, ¹H, and ¹³C NMR, mass spectrometry, and tested for their antibacterial activity.     

Triton B–Mediated Efficient and Convenient Alkoxylation of Activated Aryl and Heteroaryl Halides

A simple and convenient one-pot synthesis of aryl alkyl ethers by the alkoxylation of aryl halides with alcohol in the presence of Triton B as a base is described. The procedure is applicable for a variety of aryl and heteroaryl halides, and yields are very good. The use of a nonmetallic base and solvent-free conditions are important features of the reaction.     

Synthesis of novel 1-benzyl/aryl-4-{[(1-aryl-1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazol-4-yl)methoxy]methyl}-1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazole derivatives and evaluation of their antimicrobial activity

A series of 1-benzyl/aryl-4-{[(1-aryl-1H-1,2,3-triazol-4-yl)methoxy]methyl}-1H-1,2,3-triazole derivatives were synthesized via Cu(I) catalyzed reaction between terminal alkyne and substituted aryl or benzyl azides. The synthesized triazoles were characterized by 1H NMR, 13C NMR, IR, and mass spectral techniques. All the synthesized compounds were screened for their antimicrobial activity.     

Aptamer-based zearalenone assay based on the use of a fluorescein label and a functional graphene oxide as a quencher

Microchimica Acta - A versatile and cost-effective aptamer-based fluorescence quenching assay is described for the detection of the mycotoxin zearalenone (ZEN). Exfoliated functional graphene oxide...     

A simple and facile synthesis of novel 1,2,3-triazole substituted pyrimidine derivatives

A series of novel indole and pyrimidine scaffolds bearing 1,2,3-triazoles have been designed and synthesized using click chemistry reaction conditions. Target compounds 9a-j were synthesized in the multi-step process. In the first step 5-substituted-1-methyl-1H-indole-3-carbaldehyde 2a-b reacted with ethyl cyanoacetate 3 and guanidine hydrochloride 4 in presence of L-Proline in ethanol undergoes cyclisation to form 5a-b . Further, 5a-b condensed with various benzaldehydes to form Schiff's base 6a-f , which further proporgylated with propargyl bromide to form 7a-f . Finally, 7a-f was subjected to click-chemistry with various azides in the presence of CuSO₄.5H₂O + sodium ascorbate mixture in Dimethylformamide at room temperature to obtain 2 + 3 cycloaddition products 9a-j in high yield. All these synthetic methods are mostly green and inexpensive with excellent yields.     

NO-NSAIDs. Part 3: nitric oxide-releasing prodrugs of non-steroidal anti-inflammatory drugs

In continuation of our efforts to discover novel nitric oxide-releasing non-steroidal anti-inflammatory drugs (NO-NSAIDs) as potentially "Safe NSAIDs," we report herein the design, synthesis and evaluation of 21 new NO-NSAIDs of commonly used NSAIDs such as aspirin, diclofenac, naproxen, flurbiprofen, ketoprofen, sulindac, ibuprofen and indomethacin. These prodrugs have NO-releasing disulfide linker attached to a parent NSAID via linkages such as an ester (compounds 9-16), a double ester (compounds 17-24), an imide (compounds 25-30) or an amide (compounds 31-33). Among these NO-NSAIDs, the ester-containing NO-aspirin (9), NO-diclofenac (10), NO-naproxen (11), and the imide-containing NO-aspirin (25), NO-flurbiprofen (27) and NO-ketoprofen (28) have shown promising oral absorption, anti-inflammatory activity and NO-releasing property, and also protected rats from NSAID-induced gastric damage. NO-aspirin compound 25, on further co-evaluation with aspirin at equimolar doses, exhibited comparable dose-dependent pharmacokinetics, inhibition of gastric mucosal prostaglandin E(2) (PGE(2)) synthesis and analgesic properties to those of aspirin, but retained its gastric-sparing properties even after doubling its oral dose. These promising NO-NSAIDs could therefore represent a new class of potentially "Safe NSAIDs" for the treatment of arthritic pain and inflammation.     

Synthesis and Antimicrobial Activity of 3-{2-[(1-Aryl-1H-1,2,3-triazol-4-yl)methoxy]-5-fluorophenyl}isoxazoles

Russian Journal of General Chemistry - A novel series 3-{2-[(1-aryl-1H-1,2,3-triazol-4-yl)methoxy]-5-fluorophenyl}isoxazoles derivatives is synthesized from 1-(5-fluoro-2-hydroxyphenyl)ethanone....