DABCO-Promoted Cyclization of 2-Amino-4H-chromen-4-ones with 2,6-Dibenzylidenecyclohexan-1-ones for the Synthesis of Chromeno[2,3-b]tetrahydroquinoline

DABCO-promoted cyclization reaction of substituted 2-amino-4H-chromen-4-ones with substituted 2,6-dibenzylidenecyclohexan-1-ones was investigated under mild conditions. This reaction provided a novel and efficient access to the 7,8,9,10-tetrahydro-12H-chromeno[2,3-b]quinolin-12-ones in good yields, the exocyclic double bond of which is predominantly E-selective.