IMMOBILIZATION OF 1,4-DIAZABICYCLO[2.2.2] OCTANE (DABCO) OVER MESOPOROUS SILICA SBA-15: AN EFFICIENT APPROACH FOR THE SYNTHESIS OF FUNCTIONALIZED SPIROCHROMENES

Immobilized 1,4-diazabicyclo[2.2.2]octane (DABCO) over mesoporous silica SBA-15 has been found to be an efficient heterogeneous base catalyst for the synthesis of biologically active functionalized spirochromene derivatives via three-component reaction of isatins/acenaphthoquinone, activated methylene reagents, and 1,3-dicarbonyl compounds in aqueous media. This ecofriendly protocol offers several advantages such as a cost-effective procedure with excellent yield, short reaction time, simple workup, recovery and reusability of catalyst, good functional group tolerance, and broad scope of usable substrates. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications (R) for the following free supplemental resource(s): Full experimental and spectral details.]