Dihydropyrimidine compounds and preparation methods, pharmaceutical compositions and uses thereof

A compound of general formula (Ia), or an optical isomer, pharmaceutically acceptable salt or hydrate thereof,

• wherein:
• R1 represents a halogen, a nitrogen-containing (C4-C14)-heterocyclic group, a (C1-C6)-alkylamino or a (C1-C6)-alkoxy, in which the nitrogen-containing heterocyclic group and alkyl moiety are optionally substituted by hydroxyl, a (C1-C6)-alkoxy, a (C1-C6)-alkoxycarbonyl, an aryl, a substituted aryl or a (C1-C6)-alkyl;
• R2, for one or more occurrences, each represents a substituent selected from a halogen, nitro, hydroxyl, sulphonyl, a straight or branched (C1-C6)-alkyl, a (C1-C6)-alkoxyl, a (C1-C6)-alkoxycarbonyl, amino, a mono- or di-substituted amino, or an amido;
• R3 represents a (C1-C6)-alkyl;
• and
• R4 represents a halogen, a nitrogen-containing (C4-C8)-heterocyclic group, a (C1-C6)-alkylamino, a (C1-C6)-alkoxy, or a bi(C1-C6)-alkylamino, in which the nitrogen-containing heterocyclic group and alkyl moiety are optionally substituted by hydroxyl, a (C1-C6) -alkoxy, a (Cl-C6)-alkoxycarbonyl, an aryl, a substituted aryl, oxo or a (Cl-C6)-alkyl.