Reacción #81868

Ecuación de reacción

2-amino-5-chloro-3-nitropyridine

SnCl2

→

2,3-diamino-5,6-dichloropyridine

Disolventes

HCl

Condiciones de reacción

Tratamiento posterior

1. 1
   OtroThe compounds of the present invention may be prepared
2. 2
   Otroresulted in both reduction of the nitro group to an amino group as well as chlorination of the pyridine ring

Procedimiento

The compounds of the present invention may be prepared as follows. It has been reported that reduction of 2-amino-5-chloro-3-nitropyridine (2) by SnCl2 in concentrated HCl resulted in both reduction of the nitro group to an amino group as well as chlorination of the pyridine ring to give 2,3-diamino-5,6-dichloropyridine (4) as the only isolated product (Israel & Day, J. Org. Chem. 24:1455-1460 (1959)). We found that reduction of 2 under identical conditions as reported gave a mixture of 2,3-diamino-5-chloropyridine (3) and 2,3-diamino-5,6-dichloropyridine (4) in a ratio of 4:1. The mixture could not be separated by crystallization in water. It could be separated by preparative TLC and chromatography. Cyclization of 3 with oxalic acid gave 8-NQX 5 and cyclization of 4 with oxalic acid gave 8-NQX 6. 6,7-dichloro-8-NQX 6 was found to have a Ki of about 200 nM, which is similar to the corresponding 6,7-dichloro-QX. 6-Chloro-8-NQX 5 also was found to be about as active as the corresponding 6-chloro-QX. 6-Bromo-7-methyl-8-NQX (8) was found to have a Ki of about 200 nM. 6-NQX 11 and 6,8-diN-QX 13 also were found to be about as active as QX. ##STR8##

Fuente