ZnCl-Promoted Three-Component Reaction of 2-Aminochromenones, Aromatic Aldehydes, and Quinone Monoketals: Access to 5,6-Dihydro-12-chromeno[2,3-]isoquinolin-12-one Derivatives.

A three-component reaction of 2-amino-4-chromen-4-ones, aromatic aldehydes, and 4,4-dialkoxycyclohexa-2,5-dien-1-ones for the concise synthesis of chromeno[2,3-]dihydroisoquinoline derivatives has been investigated. This reaction involved consecutive ZnCl-promoted Micheal addition and intramolecular Friedel-Crafts alkylation. This synthetic protocol offered several advantages, including the readily accessible starting materials, good functional group tolerance, and simplicity of operation.

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

DABCO-promoted cyclization reaction of substituted 2-amino-4-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-12-chromeno[2,3-]quinolin-12-ones in good yields, the exocyclic double bond of which is predominantly -selective.

Yb(OTf)-Mediated Annulation of Cyclopropane-1,1-dicarbonitriles with 2-Aminobenzaldehydes for Synthesis of Polysubstituted Quinolines.

A Yb(OTf)-mediated annulation of cyclopropane-1,1-dicarbonitriles and 2-aminobenzaldehydes for the synthesis of polysubstituted quinolines in generally good yields was investigated. In the cascade reaction, the protocol includes ring opening, intermolecular nuclophilic addition, intramolecular nuclophilic addition, and demalononitrile aromatization, in which the malononitrile group serves as a deciduous directing group mediated by Yb(OTf).

Piperidine-Mediated [3 + 3] Cyclization of 2-Amino-4-chromen-4-ones and 2-Benzylidenemalononitriles: To Access 2-Aminochromeno[2,3-]pyridine Derivatives.

Piperidine-mediated [3 + 3] cyclization of 2-amino-4-chromen-4-ones and substituted 2-benzylidenemalononitriles was developed for the synthesis of 2-amino-4-aryl-5-chromeno[2,3-]pyridin-5-one derivatives. This novel transformation provides a highly efficient and facile route to functionalized 5-chromeno[2,3-]pyridines from readily available substrates under mild reaction conditions.