Macrocyclic bis-thioureas catalyze stereospecific glycosylation reactions

Abstract

A cyclic catalyst to pair up sugars Linking sugar molecules together to make complex carbohydrates is a geometrical challenge. For a six-carbon sugar such as glucose, there are six different possible linkage sites and also two possible configurations in which to anchor the incipient bond. Park et al. developed a ring-shaped, dimeric catalyst that pairs sugars after one of them has been modified with a chloride. The thiourea-based catalyst appears to pull away the chloride while simultaneously activating the incoming second sugar. The resultant bond-forming process reliably inverts the initial C–Cl configuration. Science , this issue p. 162