Sphingosine Kinase Inhibitor Prodrugs

A compound of the formula (I)

• and pharmaceutically acceptable salts thereof, wherein
• R1 is H, Cl or F;
• R2 is H or alkyl;
• m is 0, 1 or 2;
• n is 1, 2, 3, 4 or 5;
• and
• each R3 is independently H, —C(O)alkyl, —C(O)CH2CH2C(O)OH, R4, —C(O)NR5R6, —P(O)(OR7)2 or glucosyl, provided that at least one R3 is not H,
• wherein
• R4 is a natural or unnatural amino acid linked through the carboxyl moiety as an ester,
• R5 is H or alkyl,
• R6 is H or alkyl, and
• each R7 is independently H or alkyl.