Pyran derivatives

A tetrahydropyran derivative of formula I:

• wherein:
• R1 is hydrogen or alkyl;
• R2 is alkyl optionally substituted by one or more alkoxy groups or halogen atoms;
• X is a group of formula --NHCVR.sup.4 wherein V is oxygen or sulphur, R.sup.4 is hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, aryl, arylalkyl, amino, mono- or di-alkylamino or a group of the formula --OR.sup.5 wherein R.sup.5 is alkyl, substituted alkyl, aryl or arylalkyl, or X is a group of formula --NHSO.sub.2 R.sup.4a wherein R.sup.4a is alkyl, aryl or a group of formula --CH.sub.2 COR.sup.4b wherein R.sup.4b is alkyl or aryl, and Y is a group of formula --NR.sup.6 R.sup.7, wherein R.sup.6 is hydrogen or alkyl and R.sup.7 is alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, aryl or arylalkyl or R.sup.7 is a group of formula --COOR.sup.8 wherein R.sup.8 is alkyl or arylalkyl;
• or X is of the formula --NHSOR.sup.4a, wherein R.sup.4a is defined as hereinabove, and
• Y is alkoxy, cycloalkoxy, arylalkoxy, or of the formula --NR.sup.6 R.sup.7, wherein R.sup.6 and R.sup.7 are defined as hereinabove;
• wherein alkyl means (1-6C)alkyl, cycloalkyl means (3-7C)cycloalkyl or bridges (6-9C)bicycloalkyl, aryl means an optionally substituted 5- or 6-membered carbocyclic group, arylalkyl means aryl(1-4C)alkyl, alkoxy means (1-6C)alkoxy, cycloalkoxy means (3-7C)cycloalkoxy or bridged (6-9C)bicycloalkoxy and alkenyl means (2-6C)alkenyl.