Orally Active Melanocortin Receptor-4 Compounds

A compound of formula I:

• or an enantiomer, stereoisomer or diastereoisomer thereof, or a pharmaceutically acceptable salt thereof,
• wherein:
• R1 is —R7 or —NR8R9;
• R2 and R3 are each independently a C1 to C17 linear or branched alkyl, cycloalkyl, alkylcycloalkyl, aryl, and alkylaryl, optionally substituted with one or more substituents, and when one or more substituents are present, such substituents are the same or different and independently comprising oxo, carboxy, amino, monosubstituted amino, disubstituted amino, or nitro, and when R2 and R3 are different, including all sterioisomers thereof, provided that taken together R2 and R3 can form cycloalkyl, optionally substituted, or alternatively that taken together one of R2 and R3 and one of R8 and R9 comprising a part of R4 can form heterocycloalkyl, optionally substituted;
• R4 is —OH, —OR7, or —NR8R9;
• R5 is
• H,
• a C1 to C17 linear or branched alkyl, cycloalkyl, or alkylcycloalkyl,
• a C1 to C7 acyl group,
• sulfonyl,
• carbamoyl, or
• urea,
• in each instance optionally substituted with one or more substituents, and when one or more substituents are present, such substituents are the same or different and independently halo, amino, monosubstituted amino, disubstituted amino, hydroxy, or carboxy;
• R6a and R6b are each independently H, alkyl, haloalkyl, cycloalkyl, alkoxy, alkythio, halo, nitro, acyl, cyano, aryl, alkylaryl, aryloxy, oxo, amino, monosubstituted amino, disubstituted amino, sulfonamide, hydroxy, carboxy, or alkoxy-carbonyl;
• R7 is a C1 to C17 linear or branched alkyl, cycloalkyl, or alkylcycloalkyl, optionally substituted with one or more substituents comprising oxo, terminal amide, amino, monosubstituted amino, disubstituted amino, or nitrile;
• and
• R8 and R9 are each independently H or a C1 to C17 linear or branched alkyl, cycloalkyl, or alkylcycloalkyl, optionally substituted with one or more substituents comprising oxo, amino, monosubstituted amino, disubstituted amino, or nitrile, provided that R8 and R9 taken together can form heterocycloakyl, optionally substituted.