Abstract: Compounds of the formula I wherein m is 1 or 2; R1, R2, R4 and R5 independently of one another are hydrogen, C1-C4alkyl, C5-C7 cycloalkyl, phenyl, C1-C4alkoxy, C5-C7cycloalkoxy or phenoxy; R3, if m is 1, has one of the meanings as given above for R1, R2, R4 and R5; R3, if m is 2, is a divalent group; R6 is hydrogen or C1-C4alkyl; R7 is hydrogen, and if R6 is hydrogen then R7 may additionally be C1-C4alkyl; R8 is group A or B X is O, O—CH2— or —O(CHR14)—; n is 0-10; provided that (i) if n is 0, and X is O, then R8 is a group A; (ii) if n is other than 0, then X is O and R8 is the group A; R9 and R10 independently of one another are hydrogen or C1-C4alkyl; R11 and R12 independently of one another are C1-C4alkyl or form together with the C atom to which they are attached a 5 to 7 membered saturated carbocyclic ring; R13 is hydrogen, C1-C4alkyl, C5-C7cycloalkyl, 2-tetrahydropyranyl or Si(C1-C4alkyl)3; R14 is a group A? and R?13 has one of the meanings as given for R13 or is the group C