One Stone, Three Birds: One-Pot Synthesis of Pyrido[3,2- a ]phenoxazin-5-one Derivatives from o -Aminophenols with Triple Roles, Paraformaldehyde, and Enaminones via the Povarov Reaction.

A novel multicomponent cascade cyclization reaction in one pot for the preparation of pyrido[3,2- a ]phenoxazin-5-ones from simple o -aminophenols, paraformaldehyde, and enaminones has been established. It is noteworthy that o -aminophenol plays multiple roles serving as both a bis-nucleophile and an iminoquinone precursor, which can in situ generate aminophenoxazinones to undergo the Povarov reaction for the first time to yield pyrido[3,2- a ]phenoxazin-5-ones with a high efficiency. Moreover, the photoluminescence of pyrido[3,2- a ]phenoxazin-5-ones has polarity sensitivity and features aggregation-induced emission (AIE) characteristics, which is promising for bioimaging and theranostic applications.