Sulfinylpyridines and their use in the treatment of cancer

A compound of formula I

• or a pharmaceutically acceptable salt thereof, wherein:
• L represents —S(O)—;
• n represents 0 to 5;
• R1, R2 and R3 each independently represent H, halo, Ra1, —CN, -Aa1-C(Qa1)Rb1, -Ab1-C(Qb1)N(Rc1)Rd1, -Ae1-C(Qe1)ORe1, -Ad1-S(O)pRf1, -Ae1-S(O)pN(Rg1)Rh1, -Af1-S(O)pORi1, —N3, —N(Rj1)Rk1, —N(H)CN, —NO2, —ONO2, —ORl1 or —SRm1;
• each Aa1 to Af1 independently represents a single bond, —N(Rp1)— or —O—;
• each Qa1 to Qc1 independently represents ═O, ═S, ═NRn1 or ═N(ORo1);
• each Ra1 and Rf1 independently represents C1-6 alkyl, C2-6 alkenyl or C2-6 alkynyl each optionally substituted by one or more groups independently selected from G1a, heterocyclyl optionally substituted by one or more groups independently selected from G1b, aryl optionally substituted by one or more groups independently selected from G1c, or heteroaryl optionally substituted by one or more groups independently selected from G1d;
• each Rb1, Rc1, Rd1, Re1, Rg1, Rh1, Ri1, Rj1, Rk1, Rl1, Rm1, Rn1, Ro1 and Rp1 independently represents H, C1-6 alkyl, C2-6 alkenyl or C2-6 alkynyl each optionally substituted by one or more groups independently selected from G1a, heterocyclyl optionally substituted by one or more groups independently selected from G1b, aryl optionally substituted by one or more groups independently selected from G1c, or heteroaryl optionally substituted by one or more groups independently selected from G1d;
• or
• any of Rc1 and Rd1, Rg1 and Rh1 and/or Rj1 and Rk1 are linked together to form, together with the nitrogen atom to which they are attached, a 3- to 6-membered ring, which ring optionally contains one further heteroatom and which ring optionally is substituted by one or more groups independently selected from halo, C1-3 alkyl, C2-3 alkenyl or C2-3 alkynyl each optionally substituted by one or more halo, and =0;
• each R4 independently represents halo, Ra2, —CN, -Aa2-C(Qa2)Rb2, -Ab2-C(Qb2)N(Rc2)Rd2, -Ac2-C(Qc2)ORe2, -Ad2-S(O)qRf2, -Ae2-S(O)qN(Rg2)Rh2, -Af2-S(O)qORi2, —N3, —N(R2)Rk2, —N(H)CN, —NO2, —ONO2, —ORl2 or —SRm2;
• each Qa2 to Qc2 independently represents ═O, ═S, ═NRn2 or ═N(ORo2);
• each Aa2 to Af2 independently represents a single bond, —N(Rp2)— or —O—;
• each Ra2 and Rf2 independently represents C1-6 alkyl, C2-6 alkenyl or C2-6 alkynyl each optionally substituted by one or more groups independently selected from G2a, heterocyclyl optionally substituted by one or more groups independently selected from G2b, aryl optionally substituted by one or more groups independently selected from G2c, or heteroaryl optionally substituted by one or more groups independently selected from G2d;
• each Rb2, Rc2, Rd2, Re2, Rg2, Rh2, Ri2, Rj2, Rk2, Rl2, Rm2, Rn2, Ro2 and Rp2 independently represents H, C1-6 alkyl, C2-6 alkenyl or C2-6 alkynyl each optionally substituted by one or more groups independently selected from G2a, heterocyclyl optionally substituted by one or more groups independently selected from G2b, aryl optionally substituted by one or more groups independently selected from G2c, or heteroaryl optionally substituted by one or more groups independently selected from G2d;
• or
• any two Rc2 and Rd2, Rg2 and Rh2 and/or Rj2 and Rk2 are linked together to form, along with the nitrogen atom to which they are attached, a 3- to 6-membered ring, which ring optionally contains one further heteroatom and which ring optionally is substituted by one or more groups independently selected from halogen, C1-3 alkyl, C2-3 alkenyl or C2-3 alkynyl each optionally substituted by one or more halogens, and =0;
• each G1a, G1b, G1c, G1d, G2a, G2b, G2c and G2d independently represents halo, —CN, —N(Ra3)Rb3, —ORc3, —SRd3 or ═O;
• each Ra3, Rb3, Rc3 and Rd3 independently represents H, or C1-6 alkyl, C2-6 alkenyl or C2-6 alkynyl each optionally substituted by one or more fluoro;
• or Ra3 and Rb3 are linked together to form, along with the nitrogen atom to which they are attached, a 3- to 6-membered ring, which ring optionally contains one further heteroatom and which ring optionally is substituted by one or more groups independently selected from fluoro, C1-3 alkyl optionally substituted by one or more fluoro, and ═O;
• and
• each p and q independently represents 1 or 2,
• but with the proviso that the compound of formula I does not represent:
• 3-nitro-2-(phenylsulfinyl)pyridine,
• 3-nitro-2-(p-tolylsulfinyl)pyridine,
• 2-((4-bromophenyl)sulfinyl)-3-nitropyridine,
• 2-((3-chlorophenyl)sulfinyl)-3-nitropyridine, or
• 3-nitro-2-((3-(trifluoromethyl)phenyl)-sulfinyl)pyridine.