Highly Productive Continuous Flow Synthesis of Di- and Tripeptides in Water

The reaction of amino acid derived N-carboxyanhydrides (NCAs) with unprotected amino acids under carefully controlled aqueous continuous flow conditions realized the formation of a range of di- and tripeptide products in 60–85% conversion at productivities of up to 535 g·L–1h–1. This required a fundamental understanding of the physicochemical aspects of the reaction resulting in the design of a custom-made continuous stirred tank reactor (CSTR) with continuous solids addition, high shear mixing, automated pH control to avoid the use of buffer, and efficient heat removal to control the reaction at 1 ± 1 °C.