Pyrrolo [2,3-b] pyridine derivatives

A compound of formula I:

• wherein:
• R1 is selected from the group consisting of
• lower alkyl, lower alkenyl, lower alkinyl,
• cycloalkyl, lower cycloalkylalkyl,
• lower hydroxyalkyl,
• lower alkoxyalkyl,
• lower alkylsulfanylalkyl,
• lower dialkylaminoalkyl,
• lower dialkylcarbamoylalkyl,
• phenyl unsubstituted or substituted with one or two groups independently selected from lower alkyl, lower halogenalkoxy and lower hydroxyalkyl,
• lower phenylalkyl wherein the phenyl ring may be unsubstituted or substituted with one or two groups independently selected from lower alkyl, halogen, lower alkoxy and lower hydroxyalkyl,
• lower heteroarylalkyl wherein the heteroaryl ring may be unsubstituted or substituted with one or two groups independently selected from lower alkyl, halogen, lower alkoxy and lower hydroxyalkyl,
• lower heterocyclyl wherein the heterocyclyl ring may be unsubstituted or substituted with one or two lower alkyl groups, and
• lower heterocyclylalkyl wherein the heterocyclyl ring may be unsubstituted or substituted with one or two lower alkyl groups;
• R2 is selected from the group consisting of hydrogen,
• lower alkyl, lower alkenyl, lower alkinyl,
• cycloalkyl, lower cycloalkylalkyl,
• lower hydroxyalkyl, lower alkoxyalkyl,
• lower alkylsulfanylalkyl,
• lower dialkylaminoalkyl,
• lower dialkylcarbamoylalkyl,
• phenyl unsubstituted or substituted with one or two groups independently selected from lower alkyl, lower halogenalkoxy and lower hydroxyalkyl,
• lower phenylalkyl wherein the phenyl ring may be unsubstituted or substituted with one or two groups independently selected from lower alkyl, halogen, lower alkoxy and lower hydroxyalkyl,
• lower heteroarylalkyl wherein the heteroaryl ring may be unsubstituted or substituted with one or two groups independently selected from lower alkyl, halogen, lower alkoxy and lower hydroxyalkyl,
• lower heterocyclyl wherein the heterocyclyl ring may be unsubstituted or substituted with one or two lower alkyl groups, and
• lower heterocyclylalkyl wherein the heterocyclyl ring may be unsubstituted or substituted with one or two lower alkyl groups;
• or
• R1 and R2 together with the nitrogen atom to which they are attached form a 4-, 5-, 6- or 7-membered saturated or partly unsaturated heterocyclic ring optionally containing a further heteroatom selected from nitrogen, oxygen or sulfur, a sulfinyl group or a sulfonyl group,
• said saturated or partly unsaturated heterocyclic ring
• being unsubstituted or substituted by one, two or three groups independently selected from lower alkyl, halogen, halogenalkyl, cyano, hydroxy, lower hydroxyalkyl, lower alkoxy, oxo, phenyl, benzyl, pyridyl and carbamoyl, or
• being condensed with a phenyl ring, said phenyl ring being unsubstituted or substituted by one, two or three groups independently selected from lower alkyl, lower alkoxy and halogen;
• R3 is selected from the group consisting of hydrogen, lower alkyl, lower hydroxyalkyl,
• lower alkoxyalkyl, lower halogenalkyl, lower cycloalkylalkyl,
• lower alkanoyl, lower cyanoalkyl, lower alkylsulfonyl,
• phenylsulfonyl wherein the phenyl ring may be unsubstituted or substituted with one or two groups independently selected from lower alkyl, halogen, lower alkoxy, lower halogenalkoxy and lower hydroxyalkyl,
• phenyl unsubstituted or substituted with one or two groups independently selected from lower alkyl, halogen, lower alkoxy, lower halogenalkoxy and lower hydroxyalkyl,
• lower phenylalkyl, wherein the phenyl ring may be unsubstituted or substituted with one or two groups independently selected from lower alkyl, halogen, lower alkoxy, lower halogenalkoxy and lower hydroxyalkyl, and
• heteroaryl unsubstituted or substituted with one or two groups independently selected from lower alkyl or halogen;
• R4 is lower alkyl or cycloalkyl;
• and pharmaceutically acceptable salts thereof.