Heterocyclic compound as TYK2 pseudokinase domain inhibitor, synthetic method, and use

A heterocyclic compound or pharmaceutically acceptable salts thereof, wherein the compound is as represented by formula I;

• wherein,
• X and Y are each independently CR5 or N;
• Z is CR6 or N;
• W1 and W2 are each independently divalent group selected from the group consisting of O, S, SO2, CO, NR7CO, CONR7;
• W3 is a divalent group selected from the group consisting of CO, NR7, NR7CO, CONR7;
• R3 is substituted or unsubstituted C3-6 cycloalkyl;
• R4 is selected from the group consisting of substituted or unsubstituted C1-6 alkyl, substituted or unsubstituted C3-6 cycloalkyl;
• and R4 is optionally further substituted with R1 and R2;
• R1 and R2 are each independently selected from the group consisting of H, substituted or unsubstituted C1-6 alkyl;
• or, R1 and R2 together with the carbon to which they are attached form substituted or unsubstituted C3-6 cycloalkyl;
• R5, R6 and R7 are each independently selected from the group consisting of H, substituted or unsubstituted C1-4alkyl;
• n=1 or 2;
• unless otherwise specified, said substituted means that one or more of hydrogen atoms in the group are substituted with substituents selected from the group consisting of halogen, C1-4 alkyl, and C1-4 haloalkyl.