GB938052A - Azabenzimidazoles and their preparation - Google Patents

Abstract

The invention comprises compounds of the formulae <FORM:0938052/IV(a)/1> wherein A is an alkylene radical of 1 to 3 carbon atoms, R is a di-alkylamino group in which each alkyl group has at most 5 carbon atoms, R1 is a phenyl radical which may be substituted by a halogen atom or one or two alkoxy groups each containing at most 5 carbon atoms and R2 is hydrogen or a nitro group, and their acid-addition salts. They may be prepared by reacting an aminopyridine of the formula <FORM:0938052/IV(a)/2> or <FORM:0938052/IV(a)/3> with a phenyl acetic acid and R1CH2COOH or a functional derivative thereof, e.g. an imino ether, with, if necessary cyclization of the a -phenyl-acetyl derivative, e.g. 4-(b -diethylaminoethyl-amino-3- (a -phenylacetamido) -pyridine, first formed. Examples are given and a list of salt-forming organic and inorganic acids is provided. 2-(b - diethylaminoethylamino)- 3-amino-pyridine is prepared by reacting 2-chloro-3-nitro-pyridine with diethylamino-ethylamine to give 2-(b -diethylaminoethylamino)- 3-nitro-pyridine and then reducing this. 2-(b -diethylamino-ethylamino)- 3-amino- 5-nitro-pyridine (hydrochloride also described) is prepared similarly via 2-(b -diethylamino-ethylamino)-3,5-dinitropyridine (hydrochloride also described) and 3-amino-4-(b -diethylamino-ethylamino)-pyridine (dihydrochloride also described) similarly via 3-nitro-4-(b -diethylamino-ethylamino)-pyridine. Amino-ether starting materials are prepared by standard procedures from the corresponding nitriles. The azabenzimidazoles of the invention, which are analgesics, can be made up into pharmaceutical preparations, e.g. tablets, dragees, salves, creams, solutions, suspensions or emulsions, with suitable carriers. These may also contain preserving, stabilizing, wetting or emulsifying agents, salts for varying the osmotic pressure or buffers.