Pyrazolo[3,4-g]quinoxaline compounds which inhibit PDGF receptor protein tyrosine kinase

A compound of the formula:

• ##STR15## where:
• ------ may be a double bond;
• R.sub.1 or R.sub.2 is hydrogen, acyl, 1,2-dihydroxyethyl, 1,2-dihydroxyprop-3-yl, or ##STR16## R.sub.3 or R.sub.4 is Y--Ar the other being hydrogen;
• R.sub.5 is hydrogen, alkyl, hydroxy, alkoxy, carboxy, carbalkoxy or carbamoyl;
• R is hydrogen or alkyl
• X is hydrogen, C.sub.4 -C.sub.6 alkyl, alkenyl, hydroxy, 1,2-dihydroxyethyl, 1,2-dihydroxyprop-3-yl, alkoxy, carboxy, carbalkoxy, acyl, acyloxy, amino, mono- or di-alkyl-amino, acylamino, cyano, carbamoyl, acylcarbamoyl, mono- or di-alkylcarbamoyl, thiocarbamoyl, mono- or di-alkylthiocarbamoyl, acylthiocarbamoyl, 2,2-dialkyl-1,3-dioxolan-5-yl, 5-tetrazolyl, piperdinyl, pyridyl, phenyl or substituted phenyl where the substitution may be one or two groups independently selected from alkyl, alkoxy, carboxy, carbalkoxy, carbamoyl, mono- or di-alkylcarbamoyl, thiocarbamoyl, mono- or di-alkylthiocarbamoyl, halo or haloalkyl;
• Y is a bond, (CH.sub.2).sub.1-3, (CH.sub.2).sub.n O(CH.sub.2).sub.m, (CH.sub.2).sub.n S(CH.sub.2).sub.m, or (CH.sub.2).sub.n NR(CH.sub.2).sub.m ;
• n and m are independently 0-3 and n+m=0-3;
• x is 1-3;
• Ar is phenyl, substituted phenyl, thienyl, substituted thienyl, pyridyl, substituted pyridyl, .alpha. or .beta. naphthyl or substituted .alpha. or .beta. naphthyl where the substitution may be one or two groups independently selected from alkyl, hydroxy, alkoxy, halo, haloalkyl or cyano;
• or
• a pharmaceutically acceptable salt thereof.