prov:value
| - tuted aralkyl group, a substituted alkenyl group, a substituted alkynyl group or a substituted silyl group, with the proviso that at least one of R5, R6, R7 and R8 is an alkyl group having 1 to 12 carbon atoms; and each of R9 R10, R 11 and R 12 is independently hydrogen atom, an alkyl group, an aryl group, an allyl group, an aralkyl group, an alkenyl group, an alkynyl group, a heterocyclic group,
|