Under nitrogen atmosphere, 9-bromo-3-chloro-8-hydroxy-6,6-dimethyl-5,6-dihydro-benzo[b]carbazol-11-one (Compound S2-4, 112 mg, 0.29 mmol) and triphenylphosphine (227 mg, 3 eq.) were added with THF (2 ml), and ((R)-2,2-dimethyl-[1,3]dioxolan-4-yl)-methanol (114 mg, 3 eq.) and 2.19 N toluene solution (0.4 mL, 3 eq.) of diethyl azodicarboxylic acid were added dropwise thereto, followed by stirring at 40° C. for 12 hr under nitrogen atmosphere. The residues obtained from the reaction solution after concentration under reduced pressure were purified by silica gel column chromatography (ethyl acetate/dichloromethane) to obtain the title compound (white powder, 100 mg).
