Gram-scale synthesis of cytoxazone via dihydrooxazine formation through SiO2-promoted intramolecular substitution of a trichloroacetimidate

[Display omitted] •The gram-scale synthesis of cytoxazone was achieved.•A dihydrooxazine ring was formed with high stereoselectivity through a SiO2-promoted intramolecular substitution of a trichloroacetimidate.•A concise and efficient synthetic method was developed (total 33% yield in 5 steps from the known enantiomerically pure diol). This study developed a concise and efficient method for synthesizing cytoxazone via the corresponding dihydrooxazine intermediate. A dihydrooxazine ring was formed with high stereoselectivity through a SiO2-promoted intramolecular substitution of a trichloroacetimidate, starting from a known enantiomerically pure diol. The intermediary dihydrooxazine was successively hydrolyzed, yielding cytoxazone in the gram scale.