abstract |
Process for the preparation of a compound of formula I wherein R 1 , R 2 , R 3 and R 4 independently of one another are C 1 -C 8 -alkyl or C 1 -C 5 -hydroxyalkyl or R 1 and R 2 together with the carbon atom to which they are attached are C 5 -C 12 -cycloalkyl or R 3 and R 4 together with the carbon atom to which they are attached represent C 5 -C 12 -cycloalkyl; R 5 , R 6 , R 7 , R 8 and R 9 independently of one another are H, C 1 -C 8 -alkyl, C 2 -C 8 -alkenyl, C 5 -C 12 -aryl, C 1 -C 4 -haloalkyl, an electron attracting group or C 5 -C 12 aryl substituted with a radical selected from C 1 -C 4 alkyl, C 1 -C 4 alkoxy, halogen, and R 7 and R 8 together can also form a chemical bond; and R represents an organic linking group containing 2-500 carbon atoms and together with the carbon atoms to which it is directly attached and the nitrogen atom forms a substituted 5-, 6- or 7-membered cyclic ring structure; characterized in that a compound of the formula II wherein all of R and R 1 -R 9 are as defined in formula I is oxidized. |