Heterocyclic compound as Syk inhibitor and/or Syk-HDAC dual inhibitor

A compound of formula (I), or the optical isomers, or pharmaceutically acceptable salts thereof:

• wherein in the formula (I),
• R1 is aryl, heteroaryl or 6-membered monocyclic heterocyclyl (including saturated and unsaturated);
• aryl, heteroaryl or monocyclic heterocyclyl herein may be optionally and independently substituted by 1-3 substituents each independently selected from the group consisting of:
• halogen, C1-4 alkyl, C1-4 halogenated alkyl, C2-4 alkenyl, C2-4 alkynyl, C3-8 cycloalkyl, 3- to 8- membered heterocyclyl, aryl, heteroaryl, CN, NO2, OR8, SR8, NR8R9, C(O)R8, C(O)OR8, C(O)NR8R9, S(O)2R8 and R7.
• R2, R3 and R4 are hydrogen;
• U is selected from NR5;
• where R5 is hydrogen;
• A is selected from the group consisting of formula (II):
• wherein:
• “” refers to the connection point of formula (II) to U of the formula (I);
• B is a monocyclic aryl or bicyclic aryl group, or a monocyclic heteroaryl or bicyclic heteroaryl group, and at least one of the bicyclic aryl or bicyclic heteroaryl is aromatic, and the other ring is aromatic, saturated or partially saturated ring;
• Y is 3- to12-membered monocyclic or polycyclic heterocyclic ring;
• wherein said heterocyclic ring contains 1-4 heteroatoms each independently selected from N, O and S;
• m is 0 or 1;
• each X is independently hydrogen, halogen, C1-4 alkyl, C3-6 cycloalkyl, 3- to 6- membered heterocyclyl, CN, OR8, SR8, NR8R9, C(O)R8, C(O)OR8, C(O)NR8R9, or S(O)2R8;
• R is hydrogen, —(CH2)p—V—(CH2)qC(O)NH(OH), —V1—(CH2)p—V2—V—(CH2)qC(O)NH(OH);
• R7 is hydrogen, —(CH2)p—V—(CH2)qC(O)NH(OH), —V1—(CH2)p—V2—V—(CH2)qC(O)NH(OH), C(O)NH(OCH3),
• R8 and R9 are each independently hydrogen, C1-4 alkyl, C1-4 halogenated alkyl, C2-4 alkenyl, C2-4 alkynyl, C3-8 cycloalkyl, 3- to 8-membered heterocyclyl, aryl, or heteroaryl;
• or R8 and R9 together with the nitrogen atom to which they are attached form a 3- to 9-metacyclic ring comprising 1-2 N atom and 0, 1 or 2 heteroatoms selected from O or S;
• V is a divalent group, each of p and q is independently an integer from 0 to 10, and the V is selected from the group consisting of bond, O, S, NR11, OC(O), OC(O)O, NHC(O), NHC(O)NH, NHC(O)O, OC(O)NH, NHS(O)2, C(O), C(O)O, C(O)NH, S(O), S(O)2, S(O)2NH, or NHS(O)2NH, CH=CH, C≡C,CR12R13,C3-8 cycloalkyl, 3- to 12-member heterocyclyl, aryl or heteroaryl,
• with the prerequisite that V, p and q together form a chemically stable group;
• V1 and V2 are divalent groups selected from the group consisting of bond, O, S, NR11, and C(O)NH, with the prerequisite that the group formed by V, V1, V2, p and q is chemically stable group;
• R11 is hydrogen, C1-4 alkyl, C3-8 cycloalkyl, 3- to 8-membered heterocyclyl, aryl, heteroaryl, C(O)R8 or S(O)2R8;
• R12 and R13 are each independently hydrogen, halogen, C1-4 alkyl, C3-6 cycloalkyl, C2-4 alkenyl, C2-4 alkynyl, 3- to 8-membered heterocyclic, OR8, SR8, NR8R9, CN, C(O)R8, C(O)OR8, C(O)NR8R9, OC(O)R8, NR8C(O)R9, or S(O)2R8, or R12 and R13 together with the carbon atoms to which they are attached form 3-8 membered cyclic structure containing 0, 1 or 2 heteroatoms selected from N, O, or S;
• with a proviso that when formula (II) is
• then R1 is
• and R7 is other than hydrogen, and the definitions of V, V1, V2, p and q in R7 must ensure that the formed le group is a stable chemical structure;
• with another proviso that when R1 does not comprise structural unit
• then A is of formula (IIa), wherein R comprises structural unit
• wherein each of the alkyl, alkenyl, alkynyl, cycloalkyl, heterocyclyl, aryl and heteroaryl is each optionally and independently substituted by 1-3 substituents each independently selected from the group consisting of halogen, C1-4 alkyl, C1-4 halogenated alkyl, C2-4 alkenyl, C2-4 alkynyl, C3-8 cycloalkyl, 3- to 8- heterocyclyl, aryl, heteroaryl, CN, NO2, OR8, SR8, NR8R9, C (O) R8, C(O)OR8, C(O)NR8R9 and S(O)2R8;
• and
• the above aryl group is an aryl group having 6 to 12 carbon atoms;
• and the heteroaryl group is a 5- to 15-membered heteroaryl group.