Azetidine analogues of nucleosidase and phosphorylase inhibitors

A compound of formula (I):

• wherein:
• W and X are each independently selected from hydrogen, CH2OH, CH2OQ and CH2SQ;
• Y and Z are each independently selected from hydrogen, halogen, CH2OH, CH2OQ, CH2SQ, SQ, OQ and Q;
• Q is an alkyl, aralkyl or aryl group each of which may be optionally substituted with one or more substituents selected from hydroxy, halogen, methoxy, amino, or carboxy;
• R1 is a radical of the formula (II)
• A is selected from CH and CR2, where R2 is selected from halogen, alkyl, aralkyl, aryl, OH, NH2, NHR3, NR3R4 and SR5, where R3, R4 and R5 are each alkyl, aralkyl or aryl groups optionally substituted with hydroxy or halogen, and where R2 is optionally substituted with hydroxy or halogen when R2 is alkyl, aralkyl or aryl;
• B is selected from hydroxy, NH2, NHR6, SH, hydrogen and halogen, where R6 is an alkyl, aralkyl or aryl group optionally substituted with hydroxy or halogen;
• D is selected from hydroxy, NH2, NHR7, hydrogen, halogen and SCH3, where R7 is an alkyl, aralkyl or aryl group optionally substituted with hydroxy or halogen;
• E is N;
• G is a C1-4 saturated or unsaturated alkyl group optionally substituted with hydroxy or halogen;
• or a tautomer thereof, or a pharmaceutically acceptable salt thereof, or an ester thereof.