2-benzoxazolyl benzene derivatives and their use as UV screening agents

1. A compound of formula I

wherein

R 1 is hydrogen, C 1-20 -alkyl or C 2-20 -alkenyl;

R 2 and R 3 are independently a group —C(R 4 , R 5 )C(R 6 )═C(R 7 ,R 8 ) (a) wherein R 4 , R 5 , R 6 R 7 and R 8 are independently, hydrogen, C 1-10 -alkyl or C 2-10 -alkenyl; or C 2-10 -alkyl or C 3-10 -alkenyl containing at least one oxygen atom interrupting the hydrocarbon chain; or wherein R 4 , R 5 and R 6 are hydrogen, C 1-10 -alkyl or C 2-10 -alkyl containing at least one oxygen atom interrupting the hydrocarbon chain, or alkyl substituted by a silane or oligosiloxane moiety, and one of R 7 and R 8 is a silane or oligosiloxane moiety and the other one of R 7 and R 8 is hydrogen; or a group —C(R 4′ ,R 5′ )CH(R 6′ )CH(R 7′ ,R 8′ ) (b), wherein R 4′ , R 5′ and R 6′ are hydrogen, C 1-10 -alkyl or C 2-10 -alkyl containing at least one oxygen atom interrupting the hydrocarbon chain, or alkyl substituted by silane or oligosiloxane moiety, and one of R 7′ and R 8′ is a silane or oligosiloxane moiety and the other one of R 7′ and R 8′ is hydrogen; and

X is phenylene or naphthylene, or substituted phenylene or naphthylene.

2. A compound according to claim 1 wherein X is p-phenylene.

3. A compound of formula I

wherein R 1 , R 2 or are a lipophilic or sterically hindered substituent selected from the group consisting of silane moieties, oligosiloxane moieties, and alkenvl groups having 5 or more carbon atoms.

4. A compound according to claim 1 wherein R 2 and R 3 are a group (a).

5. A compound according to claim 1 wherein R 2 and R 3 are a group (b).

6. A compound selected from the group consisting of 1,4-Bis-[2-(5-tert.-butyl-7-allyl-benzoxazol)-yl]-benzene 1,4-bis-[2-(5-tert.-butyl-7-{3-(1,1,3,3,3-pentamethyl-disiloxanyl)-1-propyl}-benzoxazol)-yl]-benzene; 1,4-bis-[2-(7-{3-(1,1,3,3,3-pentamethyl-disiloxanyl)-1-isobutyl}-benzoxazol)-yl]-benzene; 1,4-bis-[2-(5-tert.-butyl-7-methallyl-benzoxazol)-yl]-benzene; 1,4-bis-[2-(5-tert.-butyl-7-{3-(1,3,3,3-tetramethyl-1-[(trimethyl-silyl)-oxy]-disiloxanyl)-1-isobutyl}-benzoxazol)-yl]-benzene; 1,4-bis-[2-(5-methyl-7-oct-3-en-2-yl-benzoxazol)-yl]-benzene; 1,4-bis-[2-(5-tert.-butyl-7-(1-penyl-allyl)-benzoxazol)-yl]-benzene; 1,4-bis-(2-(5-tert.-butyl-7-oct-3-en-2-yl)-benzoxazol)-yl]-benzene; 1,4-bis-[2-(5-tert.-butyl-7-oct-3-en-2-yl-benzoxazol)-yl]-benzene; and 1,4-bis-[2-(4-tert.-pentyl-7-(1-pentyl-allyl)-benzoxazol)-yl]-benzene.

7. A UV screening composition which comprises as the UV screening agent a compound of formula I according to claim 1 .

8. A compound according to claim 4 wherein R 2 and R 3 are independently a group —C(R 4 ,H)C(H)═C(H,R 8 ) wherein R 4 and R 8 are C 1-10 -alkyl.

9. A compound according to claim 4 wherein R 2 and R 3 are independently a group —C(R 4 ,H)C(H)═CH 2 wherein R 4 is C 1-10 -alkyl.

10. A compound according to claim 5 wherein R 2 and R 3 are independently a group —C(R 4′ ,H)CH═CH(H,R 8′ ) wherein R 4′ is selected from the group consisting of hydrogen, C 1-10 -alkyl, C 2-10 -alkyl containing at least one oxygen atom interrupting the hydrocarbon chain, alkyl substituted by a silane moiety, and alkyl substituted by an oligosiloxane moiety, and R 8′ is oligosiloxane moiety.

11. A compound according to claim 5 wherein R 2 and R 3 are independently a group CH 2 CH(R 6′ )CH(H,R 8′ ) wherein R 6′ is C 1-10 -alkyl and R 8 ′ is an oligosiloxane moiety.

12. A compound according to claim 3 wherein R 1 R 2 or R 3 are a lipophilic or a sterically hindered substituent selected from the group consisting of

silane moieties —SiR a R b R c , wherein R a , R b and R c each independently are C 1 –C 6 -alkyl or phenyl,

oligosiloxane moieties of the general formula IVa, lVb and lVc

wherein m=0, 1 or 2; n=1, 2 or 3 and m+n=3, R a and R b are C 1 –C 6 -alkyl or phenyl, and r is an integer from 1 to 9, and

3-octen-2-yl, 1-octen-3-yl, and 2-octenyl.