[3-nitrobenzylidene-2,3(3H,5H)-furandione in the Hantzsch pyridine synthesis. 1. A new approach to furo(3,4-b)pyridines].
The nitrobenzylidenefurandiones 7 react with acetoacetic ester (8) and ammonium acetate or 3-aminocrotonic esters (9a, b) and 2-amino-pent-2-en-4-on (9c), respectively heating in acetic acid to yield the tetrahydrofuro[3,4-b]pyridines 10. The dehydrogenation of 10 using nitric acid or activated manganese dioxide leads to the dihydrofuro[3,4-b]pyridines 12. When the reaction is carried out with the tetronic acid derivatives 7 and the enaminocarbonyl compounds 9 at 30 degrees C in tert-butanol the hexahydro-7a-hydroxyfuro[3,4-b]pyridines 11 are obtained. Treating the N,O-acetales 11 with acetic anhydride in pyridine affords the annulated lactones 10.
Görlitzer
K
K
Institut für Pharmazeutische Chemie, Technischen Universität Braunschweig, Germany. k.goerlitzer@tu-bs.de
Bartke
U
U
D005663:Furans / Q000138:chemical synthesis*; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D017895:Manganese Compounds / Q000737:chemistry; D009574:Nitro Compounds / Q000138:chemical synthesis*; D010087:Oxides / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry*; 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; D011725:Pyridines; C023666:pyridine; C016552:manganese dioxide