Heterocyclic compounds and their preparation and use

A compound of formula IV ##STR19## wherein R.sup.15 and R.sup.16 are independently hydrogen, R.sup.10 R.sup.11 R.sup.12 Si, or R.sup.13 R.sup.14 R.sup.15 'Si;

• R is hydrogen, amino, halogen, NHR.sup.6, NR.sup.6 R.sup.7, --OR.sup.4, --SR.sup.4, --SOR.sup.4, --SO.sub.2 R.sup.4, C.sub.3-10 -cycloalkyl, C.sub.4-12 -(cycloalkylalkyl), --Z--C.sub.3-10 -cycloalkyl or --Z--C.sub.4-12 -(cycloalkylalkyl);
• or
• R is phenyl or benzyloxycarbonyl, each of which is optionally substituted with one or more halogen, --CN, C.sub.1-4 -alkyl, C.sub.1-4 -alkoxy, --OCF.sub.3, --CF.sub.3, --CONH.sub.2 or --CSNH.sub.2 substituents;
• or
• R is selected from the group consisting of --OR.sup.5 Y, --SR.sup.5 Y, OR.sup.5 --Z--Y, --SR.sup.5 ZY, --O--R.sup.5 --Z--R.sup.4 and --S--R.sup.5 --Z--R.sup.4
• R.sup.4 is C.sub.1-15 -alkyl, C.sub.2-15 -alkenyl, or C.sub.2-15 -alkynyl, each of which is optionally substituted with one or more independently selected halogen, --CF.sub.3, --CN, Y, phenyl or phenoxy substituents wherein phenyl or phenoxy is optionally substituted with one or more halogen, --CN, C.sub.1-4 -alkyl, C.sub.1-4 -alkoxy, --OCF.sub.3, --CF.sub.3, --CONH.sub.2 or --CSNH.sub.2 substituents;
• R.sup.5 is C.sub.1-15 -alkylene, C.sub.2-15 -alkenylene, or C.sub.2-15 -alkynylene;
• R.sup.6 and R.sup.7 independently are hydrogen or C.sub.1-6 -alkyl;
• or R.sup.6 and R.sup.7 together form a C.sub.3 -C.sub.5 -alkylene group which together with the nitrogen atom form a 4- to 6-membered ring;
• R.sup.10, R.sup.11, R.sup.12, R.sup.13, R.sup.14 and R.sup.15 ' are independently C.sub.1 -C.sub.6 -alkyl, aryl or aryl(C.sub.1 -C.sub.3)alkyl;
• Y is a 5 or 6 membered heterocyclic group;
• and
• Z is oxygen or sulphur;
• provided that:
• 1) when R is hydrogen, amino, or halogen, R.sup.16 cannot be hydrogen;
• and 2) when R is phenyl or substituted phenyl, R.sup.15 and R.sup.16 cannot both be hydrogen.