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An efficient four-component reaction to synthesize pyrrolo[2,1-a]isoquinolines from malononitrile, aromatic aldehydes, isoquinoline, and cyclohexyl isocyanide under solvent-free conditions is described. In a convenient, simple, and efficient one-pot procedure, the domino Knoevenagel-nucleophilic cycloaddition reaction affords excellent yields of products in less than 1 h.
An efficient method for the synthesis of 3-arylidenechroman-4-ones has been developed under solvent free conditions using grinding technique. Grinding of variously substituted chroman-4-ones with aromatic aldehydes in presence of anhydrous barium hydroxide at room temperature give 3-arylidenechroman-4-ones in high yield (75-92%). Products are obtained by just acidification of the reaction mixture in ice cold water. Reaction in solid state, with enhanced rate, high selectivity and manipulative simplicity are the attractive features of this environmentally benign protocol. The chroman-4-one derivatives required for the reaction have been obtained by polyphosphoric acid (PPA) catalysed cyclisation of phenoxypropanoic acids under microwave irradiations.
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Solvent free synthesis of dihydropyrano[3,2-b]chromenediones was formulated via multi-component reactions
of kojic acid, dimedone and several substituted aromatic aldehydes catalyzed with BCl3. Reactions progressed efficiently
and the corresponding heterocyclic products were obtained in good to high yields within short period. The developed protocol is one of the better and efficient alternative method for synthesis of dihydropyrano[3,2-b]chromenediones. The simple
reaction procedure, easy separation of products, radially available catalyst are certain benefits of this reported protocol.
Some imine derivatives (1a–7d) were synthesized using a rapid and an environmentally friendly method with reaction of aromatic aldehydes (a–d) and aromatic amines (1–7) (in 1 : 1 molar ratio) in the presence of β-ethoxyethanol as a wetting reagent (2 drops) under solvent-free conditions using microwave heating.
AbstractN,N,N,’N’-Tetrabromobenzene-1,3-disulfonamide [TBBDA] is found to be a reusable catalyst for efficient synthesis of various amidoalkyl naphthols from β-naphthol, aromatic aldehydes and urea in good to high yields under solvent-free conditions.
AbstractAn efficient synthesis of bis(indolyl)methanes was developed. Bis(indolyl)methanes were synthesized starting from various aromatic aldehydes with indole under microwave irradiation and solvent-free conditions (85-98 %). Solid support SiO
Saccharin sulfonic acid (SaSA) is utilized as a highly efficient, green and inexpensive sulfonic acid-containing catalyst for the following one-pot multi-component organic transformations: (i) the condensation of dimedone (2 eq.) with aromatic aldehydes (1 eq.) leading to 1,8-dioxo-octahydroxanthenes, and (ii) the reaction of 2-naphthol (2 eq.) with arylaldehydes (1 eq.) leading to 14-aryl-14H-dibenzo[a,j]xanthenes. In these protocols, the title compounds are produced in high to excellent yields and in relatively short reaction times under solvent-free conditions.
A Facile Solvent Free Synthesis of 3-arylidenechroman-4-ones Using Grinding Technique