A facile and one-pot synthesis of new tetrahydrobenzo[b]pyrans in water under microwave irradiation

Eleven new tetrahydrobenzo[b]pyran derivatives were synthesized via a three component reaction of different aromatic aldehydes, methyl cyanoacetate and 1,3-cyclohexadione, with water as solvent under catalyst-free microwave irradiation. The structures of all the new molecules were well analysed and their structures established by using various spectral techniques (¹H NMR, ¹³C NMR, ¹⁵N NMR and HRMS). Various advantages of reported protocol are the ease of preparation, short reaction times (10 min), aqueous solvent and excellent yields (89–98%). Additionally, this method provides a clean access to the desired products by simple workup.

A multicomponent, facile and catalyst-free microwave-assisted protocol for the synthesis of pyrazolo-[3,4-b]-quinolines under green conditions

A facile, swift and ecofriendly microwave-assisted multi-component/one-pot protocol is designed for the synthesis of novel pyrazolo-[3,4-b]-quinolines at ambient temperature in aqueous ethanol as a reaction medium. The 18 novel pyrazolo-[3,4-b]-quinoline derivatives were synthesized by fusion of chosen aryl aldehyde, dimedone and 5-amino-3-methyl-1-phenylpyrazole in excellent yields (91–98%). All the molecular structures were confirmed by ¹H-NMR, ¹⁵N-NMR, ¹³C-NMR, and HRMS data analysis. Operational simplicity, easy handling, one-step simple workup procedure, mild reaction conditions, short reaction time (≤10 min), high selectivity and no by-product formation are the striking features of the protocol.

A facile, swift and ecofriendly microwave-assisted multi-component/one-pot protocol is designed for the synthesis of novel pyrazolo-[3,4-b]-quinolines at ambient temperature in aqueous ethanol as a reaction medium.