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 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,
• wherein the substituted C1-7alkyl, C1-7alkenyl, C1-7alkinyl or C3-6cycloalkyl has 1 to 5 substitutents selected from hydroxyl, halogen, C1-4alkyl, C1-4alkoxy, C1-4alkoxy substituted by 1 to 5 halogen atoms, C3-6cycloalkyl, C3-6cycloalkoxy, C3-6cycloalkylC1-5alkyl, C3-6cycloalkoxyC1-5alkyl, cyano, optionally substituted phenyl, optionally substituted phenyloxy, optionally substituted heteroaryl, optionally substituted heteroaryloxy, optionally substituted heterocyclic residue optionally attached via oxygen;
• and wherein each of phenyl, phenyloxy, heteroaryl, heteroaryloxy, heterocyclic residue optionally attached via oxygen, 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, phenyl, and phenyl substituted by 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, and cyano;
• or each of phenyl, phenyloxy, heteroaryl, heteroaryloxy, heterocyclic residue optionally attached via oxygen independently may be fused to a heterocyclic residue;
• R3 is Z-X2 wherein 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, C1-4alkyl optionally'substituted by 1, 2 or 3 halogen atoms, or acyl;
• each of anellated rings a and b is independently C5-6cycloalkyl, aryl, a heterocyclic residue, or heteroaryl;
• in free form or in salt form.