Stannous chloride dihydrate → HCID 86740880, compound

Participants

Reaction Conditions

Reaction Steps

3-(4-nitro-benzylidene)-1,2,3,9-tetrahydro-9-oxo-cyclopenta[b][1]benzopyran-7-carboxylic acid, methyl ester (3.8 g), was reacted with SnCl2.2H2O (11.5 g) in acetic acid (130 ml) and 37% HCl (26.5 ml) under stirring at 60° C. for 3 hours: after cooling the precipitate was filtered and washed with 2N HCl and water and finely dispersed in 2N NaOH. The precipitate was filtered and washed with water until neutral to give 3-(4-amino-benzylidene)-1,2,3,9-tetrahydro-9-oxo-cyclopenta[b][1]benzopyran-7-carboxylic acid, methyl ester m.p. 265°-268° C. (2.9 g), which was treated with 37% HCl (60 ml) in acetic acid (120 ml) under stirring at 100° C. for 4 hours. After cooling the precipitate was filtered and then suspended under stirring in water containing Na2HPO4 : the precipitate was filtered and washed with water to give 2.1 g of 3-(4-amino-benzylidene)-1,2,3,9 tetrahydro-9-oxo-cyclopenta[b][1]benzopyran-7-carboxylic acid, m.p. 360° C. dec., NMR (DMSO d6) δppm: 2.90 (m) (4H, C-1 and C-2 protons), 3.30 (bs) (2H, NH2), 6.64 (d) (2H, C-3 and C-5 phenyl protons), 7.01 (bs) (1H=CH--), 7.31 (d) (2H, C-2 and C-6 phenyl protons), 7.69 (d) (1H, C-5 proton), 8.19 (dd) (1H, C-6 proton), 8.59 (d) (1H, C-8 proton).

Provenance & Evidence