Aminopropanol derivatives as sphingosine-1-phosphate receptor modulators

A compound of formula I

• wherein
• R1 is C1-6alkyl;
• C1-6alkyl substituted by hydroxy, C1-2alkoxy, or 1 to 6 fluorine atoms;
• C2-6alkenyl;
• or C2-6alkynyl;
• X is O, CH2, C═O or a direct bond;
• R2 is optionally substituted C1-7alkyl, optionally substituted C1-7alkenyl, optionally substituted C1-7alkinyl, optionally substituted C3-6cycloalkyl, optionally substituted phenyl, or optionally substituted heteroaryl,
• where the substituted C1-7alkyl, C1-7alkinyl or C3-6cycloalkyl has 1 to 5 substituents selected from hydroxyl, halogen, C1-4alkyl, C1-4alkoxy, C1-4alkoxy substituted by 1 to 5 halogen atoms, C3-6cycloalkoxy, cyano, phenyloxy, heteroaryl and optionally substituted phenyl;
• and wherein the optionally substituted phenyl or optionally substituted heteroaryl, independently, may be substituted with 1 to 5 substituents selected from hydroxyl, halogen, C1-4alkyl, C1-4alkyl substituted by 1 to 5 fluorine atoms, C1-4alkoxy, C1-4alkoxy substituted by 1 to 5 fluorine atoms, cyano and phenyl;
• R3 is Z—X2, where Z is CH2, CHF or CF2, and X2 is OH or a residue of formula (a)
• wherein Z1 is a direct bond, CH2, CHF, CF2 or O, and each of R6 and R7, independently, is H, C1-4alkyl optionally substituted by 1, 2 or 3 halogen atoms, or benzyl;
• and
• each of R4 and R5, independently, is H or C1-4alkyl optionally substituted by 1, 2 or 3 halogen atoms;
• and
• the anellated rings a and b together form 2,6- or 2,7-disubstituted naphthyl, 2,5- or 2,6-disubstituted benzoxazolyl, 2,5- or 2,6-disubstituted benzofuryl, 1,4- or 1,5-disubstituted indolyl, 3,6-indazolyl, or 3,6-N-substituted-indazolyl;
• where heteroaryl, where mentioned, refers to a 5-to-8-membered aromatic ring comprising 1 to 4 heteroatoms selected from N, O and S;
• in free form or in pharmaceutically-acceptable salt form.