US Patent 11155537 Crystal of benzofuran derivative free base and preparation method

This application describes a crystal of a benzofuran derivative free base and a preparation method. Specifically, this application describes crystal A, crystal B, crystal C, and crystal D of N-((4,6-dimethyl-2-carbonyl-1,2-dihydropyridin-3-yl)methyl)-5-ethyl-6-(ethyl(tetrahydro-2H-pyran)4-yl)amino)-2-(piperidin-1-ylmethyl)benzofuran-4-carboxamide and a preparation method for the crystals. The crystals of the compound of formula (I) have great crystal stability and provides improved uses in clinical treatment.