Anticonvulsant compounds

A compound of formula (I):

• wherein,
• R1═R2═CH3, or R1═H and R2=aryl,
• wherein aryl is:
• phenyl, which is optionally substituted with one or two of CH3, OH, SO2CH3, SO2Ph, CF3, or CN;
• 1- or 2-naphthyl;
• 2-, 3-, or 4-pyridyl, which is optionally substituted with one or two of CH3, OCH3, SO2CH3, SO2Ph, F, Cl, CF3, or CN;
• or
• 2- or 3-thienyl, which is optionally substituted with one or two of CH3, OCH3, SO2CH3, SO2Ph, F, Cl, CF3, or CN
• R3═C(O)R5, wherein R5 is H, CH3, C2H5, CH(CH3)2, CHCH3CN, or aryl, wherein aryl is as defined above in relation to R2;
• C(O)—O—, or C(O)—O—R6, wherein R6 is H, a straight or branched C1 to C6 alkyl, CH2C6H5, or CH(CH2)n, wherein n is an integer from 2 to 5;
• C(O)NH2, C(O)NHR6, C(O)N(H)phenyl, C(O)N(H)CH2phenyl, C(O)N(CH3)phenyl, or C(O)NR7R8 wherein R7 and R8 are each independently a straight or branched C1 to C6 alkyl, CH2C6H5, aryl, wherein aryl is as defined above in relation to R2, or R7 and R8 together are (CH2)m, and wherein m is an integer from 3 to 5;
• OH, OCH2C6H5 or OC(O)CH3;
• S—CH3, S—C6H5, S(O)CH3, S(O)C6H5, SO2CH3, or SO2C6H5;
• NO2, NH2, NHR6, or NR7R8;
• C≡C—C(O)CH3, C≡C—C(O)CH(CH3)2, C≡C—C(O)C2H5, C≡C—C(O)C6H5, C≡C—C(O)—OH, or C≡C—C(O)—O—;
• or
• CN;
• and
• R4═H, CH3, OH, OCH3, SO2CH3, SO2Ph, F, Cl, CF3, or CN,
• or a pharmaceutically acceptable salt thereof,
• with the proviso that:
• when R1 and R2 are both CH3 then:
• R3 and R4 cannot both be OH;
• R3 cannot be OH, CO2H, CO2CH3, CO2C2H5, C(O)H, C(O)CH3, NH2, CN or NO2 when R4 is H;
• and
• R3 cannot be CO2CH3 when R4 is CH3,
• when R1 is H and R2 is phenyl then:
• R3 cannot be OH when R4 is H or OH;
• and
• R3 cannot be NH2, N(CH3)2 or NO2 when R4 is H, and
• when R1 is H, R2 is OH-substituted phenyl and R4 is H then R3 cannot be N(CH3)2.