The present invention relates to novel compounds of Formula I, their pharmaceutically acceptable derivatives, tautomeric forms, stereoisomers including R and S isomers, polymorphs, prodrugs, metabolites, salts or solvates thereof. The invention also relates to processes for the synthesis of novel compounds of Formula I, their pharmaceutically acceptable derivatives, tautomeric forms, stereoisomers, polymorphs, prodrugs, metabolites, salts or solvates thereof.