Muscarinic M1 receptor positive allosteric modulators

A compound of formula (I),

• wherein:
• A1 and A2 are each independently represents CH, CF or N;
• W is O, S, S(O) or S(O)2;
• R1 is
• R2 is
• wherein * represents point of attachment;
• R3 is OH, F, NH2 or H;
• R4 at each occurrence is independently selected from halogen, —O—CH3;
• —S—CH3, —N(CH3)2, —CH3, —CF3, —CHF2, —CH2F, —OH, —CN, phenyl, pyridyl and hydrogen;
• wherein phenyl and pyridyl are optionally substituted with one or more substituents selected from the group consisting of halogen or CH3;
• X is CH2, O or NH;
• and
• a is 0 or 1;
• and b is 1 or 2;
• or an isotopic form, a stereoisomer, a tautomer or a pharmaceutically acceptable salt thereof.