A microwave-assisted Biginelli-like three-component condensation using salicylic aldehyde derivatives, acetone, and 5-substituted
3-amino-1,2,4-triazoles instead of the urea component results in the formation of oxygen-bridged tetrahydrotriazolopyrimidine
derivatives (11,12-dihydro-5,11-methano[1,2,4]triazolo[1,5-c][1,3,5]benzoxadiazocines) in good yields and high purity. A plausible
reaction mechanism for this transformation is discussed in details using literature and experimental data.
applied in Biginelli-like MCRs leading to the formation of
oxygen-bridged benzoxadiazocines 16 (Fig. 1). Also, the
use of heterocyclic building blocks instead of urea in such
MCRs makes these reactions to be even more complicated.
7,8 A literature overview of three-component Biginelli-

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• A modified Biginelli reaction toward oxygen-bridged tetrahydropyrimidines fused with substituted 1,2,4-triazole ring