Catalyst‐Free Synthesis of Alkylpolyglycosides Induced by High‐Frequency Ultrasound

The irradiation of concentrated feeds of carbohydrates in alcoholic solution by high-frequency ultrasound (550 kHz) induces the formation of alkylpolyglycosides (APGs). This work is distinct from previous reports in that it does not involve any (bio)catalyst or activating agent, it takes place at only 40 °C, thus avoiding degradation of carbohydrates, and it selectively yields APGs with a degree of polymerization in a window of 2¿7, an important limitation of the popular Fischer glycosylation. This ultrasound-based technology proved successful with a range of different valuable carbohydrates and alkyl alcohols. The elucidation of the structure of all the produced glycosides strongly suggests that 1,6-anhydrosugars formed in situ are key intermediate species.
Authors are grateful to the CNRS, the University of Poitiers, the Ministry of Research, the Région Nouvelle Aquitaine, the MINECO (contract nos. SAF2016‐76083‐R and CTQ2015‐64425‐C2‐1‐R), the Junta de Andalucía (contract no. FQM2012‐1467) and the European Community (FEDER) for their financial supports.