Efficient and environmentally benign heterocyclization via Knoevenagel condensation followed by [4 + 2] cycloaddition resulting the synthesis of tetrahydro-1H-pyrano[2,3-d]pyrimidine derivatives starting from 2-thiobarbutiric acid, aldehydes and alkyne has been reported. Easily available ethylene glycol was used as a green promoting medium as well as solvent for the reaction progress. This methodology offers a metal and base free approach which endowed high yields with mild reaction conditions and better functional group tolerating ability. Further visible light as a source of energy, recyclability and reuse of ethylene glycol add the methodology a wide scope.

A novel facile and diastereoselective synthesis of imidazopyridine with high atom economy in water as a green solvent under synergic effect of microwave activation and phase transfer catalysis from readily available 2‐aminopyridine and electrophilic alkyne, dimethyl acetylene dicarboxylate has been developed. The strategy of the protocol involves heterocyclisation via double hydroamination of dimethyl acetylene dicarboxylate in biphasic system catalyzed by benzyltriethylammonium bromide activated by microwave irradiation. The transformation proceeded smoothly and quantitatively at an ambient temperature. The reaction sequence of the protocol was also proved by electrochemical synthesis of imidazopyridine using same starting materials under similar reaction conditions.

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A new high yielding protocol has been developed for the convenient and rapid synthesis of 2-amino-4H-pyrans by one-pot sequential reaction of aldehydes, malononitrile and cyanoketones in aqueous micellar medium using chitosan as an efficient heterogeneous, biodegradable and reusable green cata-lyst. Mild conditions with excellent conversions, cost effectiveness, short reaction times, environmental friendliness, and operational simplicity are noteworthy advantages of this method. The micellar catalytic system can be reused several times without any noticeable decrease in its activity.