Efficient one-pot synthesis of a densely functionalized tetrahydropyridine in the presence of [1,1′-binaphthalene]-2,2′-diol/indium(III) chloride (binol/InCl3) or simple Br?nsted acids as catalysts

摘要

The highly functionalized tetrahydropyridine 4 was obtained in an indium(III) chloride catalyzed multi-component reaction from benzaldehyde, 4-methoxyaniline, and ethyl acetoacetate (=ethyl 3-oxobutanoate) in the presence of [1,1′-binaphthalene]-2,2′-diol (binol). It was found that binol played a beneficial role in this reaction, allowing a substantial decrease of the amount of indium salt. Also, simple organic Br?nsted acids may serve as effective organocatalysts in this process.