The invention provides a preparation method of an IRAK4 targeted
protein degradation agent key intermediate, and belongs to the field of
drug synthesis. According to the invention, 2-pyrrolidone and a benzimidazolone compound are used as raw materials to prepare a key intermediate of the IRAK4 targeted
protein degradation agent, a
protecting group is introduced to 2-pyrrolidone, and a reaction
route is optimized, so that generation of a by-product 3-bromo-1-(3-methyl-2-oxo-2, 3-dihydro-1H-benzo [D]
imidazole-4-yl)
piperidine-2, 6-
diketone is avoided, and the yield of the IRAK4 targeted
protein degradation agent is improved. The product yield is obviously improved, the product is easier to purify, and the method has a wide application prospect and is convenient for industrialization.