Novel compounds and methods for treating multiple sclerosis

A compound of the formula I 6

• wherein:
• R1 and R2 are each independently selected from C1-C8 alkyl;
• C2-C8 alkenyl;
• C2-C8 alkynyl;
• C1-C8 alkyloxy;
• C1-C8 alkylthio;
• trifluoromethyl;
• C1-C4 alkyl substituted with phenyl;
• phenyl;
• F;
• Cl;
• NO2;
• phenoxy;
• C1-C4 alkyl substituted with phenoxy;
• thiophenyl;
• C1-C4 alkylthiophenyl;
• —COOR7;
• —N(R7)2 or —N(R7)SO2R7 where each R7 is independently hydrogen or C1-C6 alkyl;
• R3 is H or C1-C4 alkyl;
• R4 and R5 are each individually H, or when taken together form a bond;
• R6 is H;
• C1-C8 alkyl;
• C2-C8 alkenyl;
• C2-C8 alkynyl;
• —SO2CH3;
• —(CH2)nNR8R9;
• —(CH2)nCO2R8;
• —(CH2)nOR8 where n is an integer from 1 to 6, both inclusive, and R8 and R9 are each independently hydrogen;
• C1-C6 alkyl;
• C2-C6 alkenyl;
• C2-C6 alkynyl;
• phenyl;
• C1-C4 alkyl substituted with phenyl;
• —(CH2)qOH;
• or (CH2)qS(C1-C4alkyl) where q is an integer from 2 to 6, both inclusive;
• and
• X is 7
• where m is 0 or 1;
• or a pharmaceutically acceptable salt or optical isomer thereof.