A compound of formula (Ia): <chemistry id="CHEM-US-00306" num="00306"><img id="EMI-C00306" he="22.10mm" wi="62.23mm" file="US09469640-20161018-C00306.TIF" alt="embedded image" img-content="chem" img-format="tif"/></chemistry> or a pharmaceutically ubstituted lower alkyl or optionally substituted heteroaryl; R² is hydrogen or halogen; R⁴ is hydrogen; R³ is optionally substituted lower alkyl or optionally substituted aryl; m is 0, 1, 2, 3, 4, or 5; and Ar is a monocyclic heteroaryl containing 5 to 6 atoms wherein at least one atom is nitrogen. view more

The compound of claim 1, wherein R<sup/>is hydrogen.

The compound of claim 1, wherein R<sup>3 </sup>is optionally substituted phenyl.

The compound of claim 1, wherein R<sup>3 </sup>is phenyl substituted with one or more substituents selected from the group consisting of fluoro, lower alkyl, fluoro substituted lower alkyl, lower alkoxy, fluoro substituted lower alkoxy, lower and fluoro substituted lower alkylthio. view more

The compound of claim 1, wherein R<sup>3 </sup>is phenyl substituted with one or more fluoro.

A pharmaceutical composition comprising a compound of claim 1 and a pharmaceutically acceptable carrier or excipient.

A method for treating a subject suffering from melanoma, thyroid cancer or colorectal cancer, said method comprising administering to the subject an effective amount of a compound of claim 1.

The method of claim 11, wherein the melanoma is melanoma having a mutation encoding a V600E amino acid substitution.

A compound of formula (Ia): or a pharmaceutically acceptable salt thereof, wherein: L1 is a bond or —N(H)C(O)—; each R1 is optionally substituted lower alkyl or optionally substituted heteroaryl; R2 is hydrogen or halogen; R4 is hydrogen; R3 is optionally substituted lower alkyl or optionally substituted aryl; m is 0, 1, 2, or 3; and Ar is a monocyclic heteroaryl containing 5 to 6 atoms wherein at least one atom is nitrogen. view more

The compound of claim 1, wherein R2 is hydrogen.

The compound of claim 1, wherein R3 is optionally substituted phenyl.

The compound of claim 1, wherein R3 is phenyl substituted with one or more substituents selected from the group consisting of fluoro, lower alkyl, fluoro substituted lower alkyl, lower alkoxy, fluoro substituted lower alkoxy, lower alkylthio, and fluoro substituted lower alkylthio. view more

The compound of claim 1, wherein R3 is phenyl substituted with one or more fluoro.

The compound of claim 1, wherein one of the R1 substituents is optionally substituted lower alkyl containing 1-4 carbon atoms.

The compound of claim 1, wherein one of the R1 substituents is optionally substituted heteroaryl.

A pharmaceutical composition comprising a compound of claim 1 and a pharmaceutically acceptable carrier or excipient.

A compound of formula (Ia): or a pharmaceutically acceptable salt thereof, wherein: L1 is a bond; each R1 is optionally substituted lower alkyl or optionally substituted heteroaryl; R2 is hydrogen or halogen; R4 is hydrogen; R3 is optionally substituted lower alkyl or optionally substituted aryl; m is 0, 1, 2, 3, 4, or 5; and Ar is a monocyclic heteroaryl containing 5 to 6 atoms wherein at least one atom is nitrogen. view more

The compound of claim 11, wherein R2 is hydrogen.

The compound of claim 11, wherein R3 is optionally substituted phenyl.

The compound of claim 11, wherein R3 is phenyl substituted with one or more substituents selected from the group consisting of fluoro, lower alkyl, fluoro substituted lower alkyl, lower alkoxy, fluoro substituted lower alkoxy, lower alkylthio, and fluoro substituted lower alkylthio. view more

The compound of claim 11, wherein R3 is phenyl substituted with one or more fluoro.

The compound of claim 11, wherein one of the R1 substituents is optionally substituted lower alkyl containing 1-4 carbon atoms.

The compound of claim 11, wherein one of the R1 substituents is optionally substituted heteroaryl.

A pharmaceutical composition comprising a compound of claim 11 and a pharmaceutically acceptable carrier or excipient.