Heteroaryl-cyclic acetals

A compound of formula (I):

• wherein:—
• Het is a five heteroaromatic ring of the formula
• in which R1 is optionally substituted aryl, and R2 is 4-pyridyl;
• wherein aryl is selected from:
• phenyl and naphthyl;
• and aryl optional substitution is with one or more substituents selected from:
• acyl, acylamino, alkoxy, ailcoxycarbonyl, alkylenedioxy, alkylsulphinyl, alkylsulphonyl, allcylthio, aroyl, aroylamino, aryl, arylailcyloxy, arylailcyloxycarbonyl, arylallcyltbio, aryloxy, aryloxycarbonyl, arylsulphinyl, arylsulphonyl, arylthio, carboxy, cyano, halo, hydroxy, nitro, trifluoromethyl, Y3Y4N—, Y3Y4NCO—, Y3Y4NSO2—, Y3Y4N—C2-6alkylene-Z1- (where Z1 is O, NR5 or S(O)n), alkylC(═O)—Y3N—, alkylSO2—Y3N—or alkyl optionally substituted with aryl hydroxy, or Y3Y4N—;
• X2 is CH, X3 is C, X4 is N and X5 is N;
• R3 represents a group -L1-R6;
• R4 represents hydrogen, alkyl or hydroxyalkyl;
• or
• R3 and R4, when attached to the same carbon atom, may form with the said carbon atom a cycloalkyl, cycloalkenyl or heterocycloalkyl ring or a group C═CH2;
• R5 represents hydrogen or alkyl;
• R6 is hydrogen, alkyl, azido, hydroxy, alkoxy, aryl, arylalkyloxy, aryloxy, carboxy an acid bioisostere selected from the group consisting of C(═O) NHOH, —C(═O)—CH2OH, —C(═O)—CH2SH, C(═O) NH—CN, sulpho, phosphono, alkylsuiphonylcarbamoyl, arylsulphonylcarbamoyl, N methoxycarbamoyl, or 3 hydroxy-3-cyclobutene-1 ,2-dione, cycloalkyl, cycloalicyloxy, nitro, —NY 1Y2, —N(R7)—C(=Z)—R8, —N(R7)—C(=Z)-L2-R9,—NH—C(=Z)—NH—R8, —NH—C(=Z)—NH-L2-R9, —N(R7)—SO2-R8, —N(R7)—SO2-L2-R9, —S(O)nR10, —C(=Z)—NY1Y2 or —C(=Z)—OR10;
• R7 is hydrogen, alkyl, aryl, arylalkyl, or cycloalkyl;
• R8 is alkyl, alkoxy, aryl, arylalkyloxy, or cycloalkyl,;
• R9 is alkoxy, aryl, arylalkyloxy, arylalkyloxycarbonylamino, carboxy, an acid bioisostere selected from the group consisting of C(═O) NHOH, —C(═O)—CH2OH, -C(=O)-CH2SH, C(═O) NH—CN, suipho, phosphono, alkylsuiphonylcarbamoyl, arylsulphonylcarbamoyl, N methoxycarbamoyl, 3 hydroxy-3-cyclobutene-1 ,2-dione, cycloalicyl, cyano, halo, hydroxy or —NY3Y4;
• R10 is alkyl, aryl, arylalkyl, or cycloalkyl;
• L1 represents a direct bond or a straight- or branched-chain alkylene linkage containing from 1 to 6 carbon atoms and optionally substituted by halogen, hydroxy, alkoxy or oxo;
• L2 is a straight- or branched-chain alkylene linkage containing from 1 to 6 carbon atoms;
• Y1 and Y2 are independently hydrogen, alkenyl, alkynyl, aryl, cycloalkyl, or alkyl optionally substituted by alkoxy, aryl, cyano, cycloalkyl, hydroxy, oxo, —CO2R7, —CONY3Y4 or —NY3Y4;
• Y3 and Y4 are independently hydrogen, alkenyl, alkyl, alkynyl, aryl, arylalkyl, or cycloalkyl;
• Y5 is hydrogen, alkyl, aryl, arylalkyl, —C(=Z)R10, —C(=Z)OR10 or —SO2R10;
• Z is an oxygen or sulphur atom;
• m is zero or an integer 1 or 2;
• and
• n is zero or an integer 1 or 2;
• or an N-oxides thereof, or a pharmaceutically acceptable salt thereof.