An efficient method was developed for the synthesis of 3,4,5-trisubstituted and 3,5-disubstituted
isoxazoles by using continuous-flow microwave-heated microreactors. A study on the
separate effects of the temperature, continuous-flow regime, and microwave irradiation
showed that the continuous-flow regime had important effects for less reactive diketones,
where microwave heating enhanced the reaction, permitting the formation of 5-methyl-3-phenylisoxazole,
which was not formed in the absence of microwaves.
Key words
heterocycles - cyclizations - condensation - microwaves - continuous-flow reactors
- microreactors