Abstract: The present invention provides a small molecule compound. The small molecule compound is a compound represented by the following formula (1), or a stereoisomer, geometric isomer, tautomer, hydrate, solvate, and pharmaceutically acceptable salt or prodrug thereof, wherein R1 to R5 are each independently selected from C or N; and R is selected from cycloalkyl, substituted cycloalkyl, heterocycloalkyl, substituted heterocycloalkyl, aryl, substituted aryl, heteroaryl, or substituted heteroaryl. The small molecule compound of the present invention can inhibit the JAK kinase, and is particularly used as a JAK1/Tyk2 dual inhibitor and a Tyk2 specific inhibitor.

Abstract: Provided in the present invention is a small molecule compound, which is characterized in that it is a compound or a stereoisomer, geometric isomer, tautomer, racemate, hydrate, solvate, metabolite, and pharmaceutically acceptable salt or prodrug of the compound as represented by the following structural formula: formula (I). The small molecule compound of the present invention is applicable as a highly efficient and specific JAK kinase inhibitor, specifically a Tyk2 inhibitor and/or a JAK1 inhibitor, and/or a JAK1/Tyk2 dual inhibitor.