Naphthopyran chloroaldehydes

The short and convenient synthesis of novel naphthopyranoquinolines from naphthopyran chloroaldehydes via the Doebner-Miller synthesis was developed in the laboratory of J.K. Ray. The chloroaldehydes were treated with 2.5 equivalents of a substituted aniline in ethanol in the presence of 2N HCI to afford enaminoimine hydrochlorides in good yield. These hydrochloride salts were exposed to heat at a temperature slightly above their melting point, resulting in ring-closure and elimination of one equivalent of arylamine hydrochloride. 

Sami, I., Kar, G., Ray, J. K. Synthesis of polycyclic oxacoumarins, potential antitumor agents and a short and convenient synthesis of naphthopyranoquinolines from naphthopyran chloroaldehydes. Tetrahedron 992, 48, 5199-5208. 

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See also in sourсe #XX -- [ ]

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