Preparation of glycoside precursors in flow from food flavours containing a phenolic hydroxyl group

Flavour precursors are finding increased utility within the tobacco industry to offset the diminishing aroma of cigarettes with the development of low tar cigarettes. Ethyl vanillin (EV) glucoside serves as an important flavour precursor, and the synthesis of its intermediate (EV-O-acetyl-beta-d-glucopyranoside, 2) in a batch reaction, prolonged reaction times have been observed, thereby limiting its industrial applications. The application of continuous flow chemistry offered a faster and more scalable approach for the preparation of glycoside precursors. Initial exploration in batch reactions established general conditions for the synthesis of 2, and further optimization in continuous flow reactions facilitated the synthesis of a range of glycoside precursors. These were achieved using tetra-O-acetyl-alpha-d-glycosyl bromide (1) in conjunction with various food flavours containing phenolic hydroxyl groups.Graphical abstractThe preparation of glycoside precursors was studied by advanced flow reactor (AFR) system and conventional coil flow chemistry system.