GB785355A - Substituted pteridine derivatives - Google Patents

Abstract

The invention comprises 2-acylamino-10-formyl-pteroyl-glutamic acids and their preparation by the following methods:-(1) reacting an N - {p - [(2 - acylamino - 4 - hydroxy - 6 - pteridylmethylene) imino] benzoyl} glutamic acid with formic acid, or with a tri-(lower alkyl) ammonium formate at an elevated temperature; (2) reacting a 2-acylamino-4-hydroxy-6-formylpteridine with L( - )N-(p-aminobenzoyl) glutamic acid in presence of formic acid, or with L( - )N-(p-formamidobenzoyl) glutamic acid, or with L( - )N - (p - aminobenzoyl) glutamic acid and a tri-(lower alkyl) ammonium formate at an elevated temperature; (3) reacting a 2-acylamino-4-R1-6-di-R-pteridine (R being alkoxy or aralkoxy and R1 being hydroxy, alkoxy, aryloxy or aralkoxy) with L( - )N-(p-aminobenzoyl) glutamic acid and formic acid. The above processes in which a tri-(lower alkyl) ammonium formate, i.e. one containing at most 5 carbon atoms in each alkyl radical, is used are advantageously performed at 150 DEG C. at superatmospheric pressure in an excess of the formate, the other processes being advantageously performed at an elevated temperature, e.g. at reflux, in presence of a solvent such as a lower alcohol, dioxan, ether or an inert chlorinated hydrocarbon, or in an excess of formic acid, preferably with addition of a small amount of acetic anhydride. The invention further comprises the preparation of 10-formyl pteroylglutamic acid by the following methods:-(1) reacting a 2-amino-4-R1-6-di-R-methylpteridine with L( - )N-(p-aminobenzoyl) glutamic acid and an excess of formic acid at an elevated temperature, preferably in an excess of substantially pure formic acid, which may contain a small amount of acetic anhydride, at about 70-80 DEG C.; (2) reacting 2-amino-4-hydroxy - 6 - formyl - pteridine with L( - )N-(p-aminobenzoyl) glutamic acid and a trialkyl ammonium formate, e.g. triethylammonium formate, at an elevated temperature, advantageously at 150 DEG C. under superatmospheric pressure in an excess of the formate. Lastly the invention also comprises the process of hydrolysing a 2-acylamino-10-formyl-pteroylglutamic acid to produce pteroylglutamic acid. The hydrolysis may be effected with an inorganic or organic acid or base, and advantageously with an inorganic acid or base in water or an inert organic solvent at elevated temperatures. In examples 2-acetamido-10-formyl pteroylglutamic acid and 10-formyl pteroylglutamic acid are prepared by each of the above methods. Other 2-acylamino-10-formyl pteroylglutamic acids in which the acyl substituent is alkyl-, aryl-or aralkylcarbonyl are also referred to. Starting material. L( - )N - (p - formamidobenzoyl) glutamic acid is prepared by heating L( - )N-(p-aminobenzoyl) glutamic acid with concentrated formic acid. Specifications 785,353 and 785,354 also are referred to.