Pyrazolo3,4-
bquinolines and pyrazolo3,4-
cpyrazoles have been synthesized from β-chlorovinylaldehydes and hydrazine hydrate/phenylhydrazine using
p-TsOH under microwave irradiation.
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By coupling microwave activation and PTC conditions, substantial improvements in numerous organic reactions are described under simple and safe conditions. Generally, better yields are obtained under ...faster and cleaner reactions when compared to those from conventional heating. Very often, solvent can be avoided during the reaction when the electrophile is a liquid and can therefore act both as a reagent and the organic phase, leading to efficient green chemistry procedures.
Beckmann rearrangements of benzaldehyde and 2-hydroxyacetophenone were largely improved by performing solvent-free reactions in the presence of one equivalent of anhydrous zinc chloride. When ...compared to conventional heating under the same conditions, yields are significantly enhanced under microwave activation.
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Microwave activation coupled with dry media technique as a green chemistry procedure has been applied to synthesis of a series of some new title compounds. They have been obtained by the reaction of ...in situ synthesized 1,3-dihydro-3-2-(phenyl/4-fluorophenyl)-2-oxoethylidene)-indol-2(1H)-one (4a, b) with substituted aminobenzenethiols (5a—d). The key intermediates 4a, b were also prepared in one step by this improved technique by reacting isatin and substituted acetophenones (2a, b). The results obtained under microwave irradiation when compared with that following conventional method demonstrate the versatility of the process. The title compounds 7a—e have also been screened for their antifungal and antitubercular activity, 7a and 7e showing maximum inhibition of growth of Alternaria alternata and Fusarium oxysporium and 7b, c, e revealing significant antitubercular activity.
A highly efficient CC bond cleavage of unstrained aliphatic ketones bearing β‐hydrogens with olefins was achieved using a chelation‐assisted catalytic system consisting of (Ph3P)3RhCl and ...2‐amino‐3‐picoline by microwave irradiation under solvent‐free conditions. The addition of cyclohexylamine catalyst accelerated the reaction rate dramatically under microwave irradiation compared with the classical heating method.
A recyclable heterogeneous hydroxyapatite-supported palladium(0) catalyst was prepared by a simple procedure and successfully applied for the selective reduction of carbon-carbon double bond in
α
,
β
...-unsaturated ketones using HCOONH
4
as hydrogen transfer agent. The workup procedure is simple, and the catalyst could be recovered by simple filtration and recycled for five consecutive runs without significant loss of activity.
Novel isoxazolines and isoxazoles of N-substituted saccharin derivatives are synthesized in good yields by 1,3-dipolar cycloaddition of
N-allyl or propargyl N-substituted saccharin with arylnitrile ...oxide under solvent-free microwave irradiation. In this process, the yields were significantly improved over conventional heating, without alteration of the selectivity. The regioselectivity as well as the nonthermal specific microwave effect are discussed.
A new efficient and environmentally friendly green chemistry procedure for the syntheses of a series of 8-substituted-2-carboxy-2,3-dihydro-1,5-benzothiazepines under microwave irradiation and ...solvent-free conditions is described. Results were compared with those obtained following classical thermal method. A judicious choice of the reaction conditions allowed the final products - to be generated in excellent yields in a one-step procedure, whereas experiments under thermal conditions led to benzothiazepines along with other products in lower yields with tedious work-up.
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