Abstract: Compounds of formula I ##STR1## where A is OH, B is H, C.sub.1-4 alkyl optionally substituted by C.sub.1-4 alkoxy carbonyl, C.sub.2-4 alkenyl, CONR.sub.2 or COR.sub.4 R.sub.1 is H, R.sub.2 is C.sub.1-4 alkyl, and R.sub.4 is C.sub.1-4 alkyl, or phenyl, optionally substituted by carboxy have pesticidal and especially fungicidal activity. Many of the compounds are novel and these compounds per se, form part of the invention.

Abstract: There are described new pyrimidine derivatives of the general formula I ##STR1## in which n is 0, 1 or 2;R.sub.1 is(a) the group --CXR.sub.5, where X is oxygen or sulphur and R.sub.5 is hydrogen, a nitrogen or sulphur containing heterocyclic group, which can contain other hetero atoms, optionally substituted alkenyl, acyl, alkoxycarbonyl, alkyl substituted by aryloxy, or optionally substituted mono- or dialkylamino; or R.sub.5 is the group --NHR.sub.6, where R.sub.6 is substituted amino, substituted carbamoyl, optionally substituted alkylsulphonyl, acyl or arylsulphonyl, and when n is 0 or when X is sulphur, R.sub.5 can also be alkyl, haloalkyl, aryl, aralkyl, alkoxycarbonylalkyl or arylamino;(b) cyano or the group --CXYR.sub.7, where X and Y are the same or different and are oxygen, sulphur or optionally substituted imino and R.sub.