Shanghai Meiyue Biotech Development Co. Ltd. has synthesized spiro compounds acting as complement factor B (CFB) inhibitors reported to be useful for the treatment of age-related macular degeneration, glomerulonephritis, atypical hemolytic uremic syndrome, membranous nephropathy, myasthenia gravis, paroxysmal nocturnal hemoglobinuria, diabetic retinopathy and rheumatoid arthritis, among others.