Patent ID: 8877961

Claim:
A compound of formula (II) wherein R1 represents a 1-phenyl-C 1 -C 4 alkyl or 1-naphthyl-C 1 -C 4 alkyl group, wherein the phenyl or naphthyl moiety of R1 is unsubstituted or substituted with one or more C 1 -C 4 alkoxy groups and the carbon atoms in 2-, 3-, and/or 4-position of the alkyl part of R1 are, independently of the phenyl or naphthyl moiety of R1 and independently of one another, unsubstituted or substituted with C 1 -C 4 alkoxy and/or silyloxy or are unsubstituted or substituted with one C 1 -C 4 alkoxy group and/or silyloxy group per carbon atom; R2 represents a C 1 -C 6 alkyl group or an unsubstituted or substituted benzyl group, and R3 represents a C 1 -C 6 alkyl group or an unsubstituted or substituted benzyl group.