Silica bonded n-propyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride (SB-DABCO): A highly efficient, reusable and new heterogeneous catalyst for the synthesis of 4H-benzo[b]pyran derivatives

The reaction of 3-chloropropyl silica with diazabicyclo[2.2.2]octane in dry acetone affords silica bonded n-propyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride (SB-DABCO) as a new basic catalyst. The catalyst is used for the efficient synthesis of 4H-benzo[b]pyran derivatives via one-pot three-component reaction of cyclic ketones/1,3-diketones with aromatic aldehydes and alkylmalonates.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (171 K)Download as PowerPoint slideHighlights► Introducing a new catalyst for organic transformations. ► Introducing an efficient new method for synthesis of 2-amino-4H-benzo[b]pyrans. ► Superiority of the catalyst in comparison with the reported catalysts. ► Generality and simplicity of the method, high yields and short reaction times. ► Environmental compatibility, non-toxicity, low cost and recoverability of the catalyst.