| abstract |
An internal electron-donor compound selected from the 1,3-diethers of formula (I) n nin which R is a C 1 –C 10 alkyl group, R 1 is a linear or branched primary alkyl radical having at least three carbon atoms, optionally containing a heteroatom, and R 2 is a secondary alkyl or cycloalkyl radicals different from i-propyl, optionally containing a heteroatom. |