Controlled photo-flow oxidative reaction (UV-FOR) platform for ultra-fast phthalide and API synthesis

An integrated photo-flow oxidative reaction (UV-FOR) platform approach is presented for the synthesis of phthalides. The current protocol is catalyst-free, and uses economical and abundant hydro-carbons and hydrocarbon derivatives such as benzoic acid, benzene, and xylene, as starting materials. The reaction is performed using oxygen as a green oxidant in a time- and labour-efficient manner. This integrated approach has been shown to be successful in making a UV-FOR platform suitable for the on-demand synthesis of phthalides and their further syntheses to 2-arylmethylbenzoic acids and arylogous Michael addition products under relatively mild conditions. The current protocol was further extended to the gram scale synthesis of an ischemic stroke-relevant active pharmaceutical ingredient (API), 3-N-butylphthalide (NBP), in a continuous flow process.