Exploiting the Divergent Reactivity of a-Isocyanoacetate: Multicomponent Synthesis of 5-Alkoxyoxazoles and Related Heterocycles
A novel multicomponent synthesis of 5-alkoxyoxazoles, based on a new reactivity profile of a-isocyanoacetates, is described. Thus, simply heating a solution of amine, aldehyde, and a-(EWG-phenyl)-a-isocyanoacetate or a-(4-pyridyl)-a isocyano acetate (EWG=electron-withdrawing group) in toluene provided 5-alkoxyoxazoles in good to excellent yields. Reaction of the 5-alkoxyoxazoles with various a,b-unsaturated acyl chlorides led to the formation of epoxytetrahydropyrrolo- [3,4-b]pyridin-5-ones by a domino N-acylation/Diels–Alder cycloaddition sequence. Subsequent fragmentation under basic conditions provided 6,7-dihydro- 5H-pyrroloACHTUNGTRENUNG[3,4-b]pyridin-5-ones. A four-component synthesis of the pyridin-5-one compounds, without isolation of the 5-alkoxyoxazole, was subsequently developed.
Record created on 2011-02-17, modified on 2016-08-09