Ergoline derivatives as dopamine receptor modulators

A compound of formula I:

• wherein:
• R1 is —C(═O)NRaRb, —C(═O)ORc, (C1-C6)alkyl, (C1-C6)alkanoyl, (C1-C6)alkoxycarbonyl, or (C1-C6)alkanoyloxy, wherein any (C1-C6)alkyl, (C1-C6)alkanoyl, (C1-C6)alkoxycarbonyl, or (C1-C6)alkanoyloxy can optionally be substituted with one or more halo, hydroxy, (C1-C6)alkoxy, (C1-C6)alkanoyl, (C1-C6)alkoxycarbonyl, (C1-C6)alkanoyloxy, or NRdRe;
• R2 is H or (C1-C6)alkyl;
• R3 is methyl;
• R4 is H, halo, —C(═O)NRhRk, —C(═O)ORc, (C1-C6)alkyl, (C1-C6)alkanoyl, (C1-C6)alkoxycarbonyl, or (C1-C6)alkanoyloxy, wherein any (C1-C6)alkyl, (C1-C6)alkanoyl, (C1-C6)alkoxycarbonyl, or (C1-C6)alkanoyloxy can optionally be substituted with one or more halo, hydroxy, (C1-C6)alkoxy, (C1-C6)alkanoyl, (C1-C6)alkoxycarbonyl, (C1-C6)alkanoyloxy, or NRmRn;
• Ra and Rb are each independently H, (C1-C6)alkyl, —C(═O)NRfRg, or (C1-C6)alkanoyl, wherein any (C1-C6)alkyl or (C1-C6)alkanoyl can optionally be substituted with one or more NRfRg;
• or Ra and Rb together with the nitrogen to which they are attached form a heterocyclic ring;
• Rc is H, (C1-C6)alkyl, or aryl;
• Rd and Re are each independently H or (C1-C6)alkyl;
• or Rd and Re together with the nitrogen to which they are attached form a heterocyclic ring;
• Rf and Rg are each independently H or (C1-C6)alkyl;
• or Rf and Rg together with the nitrogen to which they are attached form a heterocyclic ring;
• Rh and Rk are each independently H, (C1-C6)alkyl or (C1-C6)alkanoyl, wherein any (C1-C6)alkyl or (C1-C6)alkanoyl can optionally be substituted with one or more NRfRg;
• or Rh and Rk together with the nitrogen to which they are attached form a heterocyclic ring;
• and
• Rm and Rn are each independently H or (C1-C6)alkyl;
• or Rm and Rn together with the nitrogen to which they are attached form a heterocyclic ring;
• or a salt thereof.