| prov:value
| - and are a C1 -C18 -alkyl group, a C2 -C18 -alkenyl group, a C2 -C18 -alkynyl group, a C5 -C12 -cycloalkyl group, a C6 -C10 -bicycloalkyl group, a C5 -C8 -cycloalkenyl group, a C6 -C10 -aryl group, a C7 -C9 -aralkyl group or a C7 -C9 -aralkyl group, substituted by C1 -C4 -alkyl or phenyl, or R6 and R7 together are a radical of the formula II or III ##STR35## in which R1, R2, R3, R4 and R5 are as de
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