Modafinil Synthesis Using an Eosin Y-photocatalytic Gel Formed by Autocatalyzed Thiol-Ene Crosslinking

Abstract

Utilizing visible wavelength photons to drive chemical transformations in photocatalysis has become increasingly popular due to the promise of sustainability, safety, and modularity. Heterogeneous photocatalysis further allows for simplified separation and reuse of photocatalysts from reaction systems. Described herein is a proof-of-concept for a heterogeneous catalysis platform based on an Eosin Y photocatalyst network (EY-gel) formed by an autocatalyzed thiol-ene crosslinking reaction. The Eosin Y photocatalyst is modified with an acrylate handle, allowing for both catalysis of and participation in the thiol-ene crosslinking reaction, thus incorporating the catalyst into the gel framework. The produced EY-gel takes the form of micron-sized spherical particles due to the use of a relative non-solvent for the gel components during the crosslinking reaction, allowing for collection through simple filtration. The EY-gel is shown to be effective for the synthesis of the narcolepsy drug Modafinil via the oxidation of 2-[(diphenylmethyl)thio]acetamide, and also shows modest recyclability over multiple use cycles.