Idene derivatives and process for the preparation thereof

An indene derivative of formula (I) or a pharmaceutically acceptable salt thereof:

• wherein,
• R1 is C1-6 alkyl, C1-6 alkenyl or C3-6 cycloalkyl, which is unsubstituted or substituted with one or more phenyl groups;
• R2 is H, CN, CO2Ra, CH2CO2Ra, CONRbRc,
• or phenyl;
• R3 is C1-6 alkyl, C3-6 cycloalkyl, or naphthyl, phenyl,
• which is unsubstituted or substituted with one or more substituents selected from the group consisting of halogen, CN, NH2, NO2, ORa, phenyloxy, C1-6 alkyl and C3-6 cycloalkyl;
• and
• R4, R5, R6 and R7 are each independently H, OH, OSO2CH3, O(CH2)mRe, CH2Rf, OCOCH2ORg, OCH2CH2ORg or OCH2CH═CHRg, or R5 and R6 together form OCH2O;
• in which Ra is H, or C1-6 alkyl or C3-6 cycloalkyl, which is unsubstituted or substituted with one or more halogens;
• Rb and Rc are each independently H, C1-6 alkyl or C3-6 cycloalkyl;
• Rd is O, S or NRa;
• Re is H, halogen, C3-6 cycloalkyl, naphthyl,
• or phenyl, which is, unsubstituted or substituted with one or more substituents selected from the group consisting of halogen, CN, NH2, NO2, ORa, CF3 and COORa;
• Rf is OCH2CH2Rg or
• Rg is phenyl, which is unsubstituted or substituted with one or more substituents selected from the group consisting of halogen, CN, NH2, NO2 and ORa;
• and
• m is an integer in the range of 1 to 5.