Abstract
A highly efficient and green protocol for the synthesis of pyrimido[4,5-b]quinolines has been described. The one-pot multicomponent reaction of dimedone with arylaldehydes and 6-amino-1,3-dimethyluracil in the presence of N,N-diethyl-N-sulfoethanaminium chloride ([Et3N–SO3H][Cl]) as an ionic liquid (IL) catalyst under solvent-free conditions afforded the mentioned compounds in high yields and short reaction times. Our protocol is superior to many of the reported protocols in terms of two or more of these factors: the reaction times, yields, conditions (solvent-free versus usage of organic solvents), temperature and catalyst amount.
An environmentally benign, one-pot, A3-coupling reaction of various aldehydes, amines and terminal alkynes for the synthesis of propargylamine was catalysed by Amberlyst A-21 supported CuI, under heterogeneous and solvent-free conditions.
A highly efficient and improved synthetic methodology for the preparation of 3,4-dihydropyrimidin-2(1H)-one derivatives in good to excellent yield via Biginelli reaction of β-ketoesters/β-diketone, urea/thiourea and various aldehydes using new, efficient and recyclable sulfated polyborate catalyst under the solvent-free condition is reported.
A combinatorial library of benzylpyrazolyl coumarin derivatives have been synthesized by a green one-pot four-component reaction between aryl hydrazine/hydrazine hydrate (1), ethyl acetoacetate (2), aromatic aldehydes (3) and 4-hydroxycoumarin (4) catalyzed by niobium pentachloride with silver salt under solvent-free conditions has been developed. Experimental simplicity, simple work-up procedure and solvent-free reaction condition at room temperature are important features of the present protocol.
A Facile Solvent-Free Route for One-Pot Multicomponent Synthesis of Benzylpyrazolyl Coumarins Derivatives in Presence of Effective Synergetic Catalytic System