Biocatalytic Oxidation of Aromatic Compounds by Spore-Based System

Enzyme-based catalyzed reactions are of increasing importance in organic synthesis as they are eco-friendly and allow a multitude of selective and efficient reactions in aqueous system. In this work, we used Bacillus amyloliquefaciens spores instead of laccase for organic synthesis because the former had plenty of CotA-laccase on their surface. The yields of spore catalyzed cross-coupling of substituted aromatic amines such as 1,2-phenylenediamine and 2-aminophenol to corresponding phenazine and phenoxazinone reached 70% and 85%, respectively. By coupling with TEMPO, a spore–TEMPO system was developed for the oxidation of primary benzylic alcohols such as benzyl alcohol, 4-methoxybenzyl alcohol, and 3,4-dimethoxybenzyl alcohol to corresponding benzaldehydes with excellent selectivity (99%, 98%, and 98%, respectively) and good yields (approximately 91%, 95%, and 96%, respectively). The developed spore-based systems show several advantages including eco-friendliness, ease of operation and storage, low cost, recyclability, sustainability, and no need for enzyme purification or immobilization. These findings may have promising implications for developing a new eco-friendly and cost-effective technology for organic synthesis.