Patent ID: 8084603

Claim:
A compound of the general formula I where R 1 and R 2 are fluorine and R 3 and R 4 are hydrogen, or R 1 and R 3 are fluorine and R 2 and R 4 are hydrogen, or R 1 and R 4 are fluorine and R 2 and R 3 are hydrogen, Y 1 is NR a , where R a is hydrogen or unsubstituted or substituted alkyl, alkenyl, alkadienyl, alkynyl, cycloalkyl, bicycloalkyl, cycloalkenyl, heterocycloalkyl, aryl or heteroaryl, Y 2 is NR b , where R b is hydrogen or unsubstituted or substituted alkyl, alkenyl, alkadienyl, alkynyl, cycloalkyl, bicycloalkyl, cycloalkenyl, heterocycloalkyl, aryl or heteroaryl, Z 1 and Z 2 are each O and Z 3 and Z 4 are each O.