[3-(Nitrobenzylidene)-2,4(3H,5H)-furandione in the Hantzsch-pyridine synthesis 2. 6,7-Dihydrophthalide].
Melting the 3-(o- and p-nitrobenzylidene)tetronic acids 2a and 2c with the enaminocarbonyl compounds 1 at 70-90 degrees C yields the hexahydro-7a-hydroxyfuro[3,4-b]-pyridines 3, while with the m-nitro compound 2b at 100 degrees C the 6,7-dihydrophthalides 4 are obtained. Dehydrogenation of the dihydro derivatives 4 with activated manganese dioxide affords the phthalides 5.
Görlitzer
K
K
Institut für Pharmazeutische Chemie, Technischen Universität Braunschweig, Germany. k.goerlitzer@tu-bs.de
Bartke
U
U
D005663:Furans / Q000138:chemical synthesis* / Q000737:chemistry*; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D017895:Manganese Compounds / Q000737:chemistry; D009574:Nitro Compounds / Q000138:chemical synthesis*; D010087:Oxides / Q000737:chemistry; D010795:Phthalic Acids / Q000138:chemical synthesis*; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
C468931:3-nitrobenzylidene-2,3(3H,5H)-furandione; D005663:Furans; D007202:Indicators and Reagents; D017895:Manganese Compounds; D009574:Nitro Compounds; D010087:Oxides; D010795:Phthalic Acids; C016552:manganese dioxide