PYRROLO[1,2-b]-2-PYRIDAZINONE COMPOUNDS AS 5-HT4 RECEPTOR AGONISTS

A compound of formula (I),

• or an isotopic form, a stereoisomer or a pharmaceutically acceptable salt thereof,
• wherein:
• R1 represents hydrogen, alkyl or cycloalkyl;
• R2 represents hydrogen, hydroxy, halogen, alkyl or cycloalkyl;
• A is heterocyclic ring selected from the group consisting of:
• R3 is hydrogen or selected from the group consisting of:
• B is selected from hydrogen, alkyl, cycloalkyl, haloalkyl, hydroxyalkyl, —SO2-alkyl, —COCH3, —COO-alkyl, or —CO—(CH2)m—OH;
• wherein, m is an integer from 0 to 5;
• Y at each occurrence is independently selected from hydrogen, hydroxy, halogen, haloalkyl, hydroxyalkyl, —COOH, —COO-alkyl, —O-alkyl, —S-alkyl or —NRaRb;
• D represents CH or N;
• n is an integer from 0 to 5;
• Ra at each occurrence is independently selected from hydrogen, alkyl, cycloalkyl or alkoxy;
• Rb at each occurrence is independently selected from hydrogen, alkyl, cycloalkyl or alkoxy;
• R4 represents hydrogen, hydroxy, halogen, alkyl or cycloalkyl;
• and
• b represents 1 to 3.