Four-Component Cyclization of Naphthol/Thionaphthol/ Naphthylamine, Formaldehyde, and DBU in Water

摘要

A practical and environmentally benign cascade multicomponent condensation of naphthol/thionaphthol/ naphthylamine, formaldehyde, and DBU in water without any catalysts has been achieved. A wide variety of dihydrooxazine, dihydrothiazine, and tetrahydrobenzoquinazoline derivatives N-substituted with a tether bearing a caprolactam unit were afforded in moderate to good yields. The advantages of being cost-effective, metal-free, and easily handled and the use of water as medium made this protocol conform with the principle of green synthesis.

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