Dehydration and catalytic cracking reactions can be combined to convert glycerol into light olefins using solid acid catalysts. The combination is suitable for a singlestep process to convert glycerol into light olefins at high temperatures (26−36% selectivity at 873 K). However, large quantities of carbon oxides are produced (31−39% CO x selectivity), and catalyst deactivation also occurs. High light olefin selectivity (62−65%) and a smaller quantity of carbon oxides (11−12% CO x selectivity) can be obtained by using a tandem process involving the dehydration of glycerol and subsequent catalytic cracking of the dehydration products (mainly acetol and acrolein). Furthermore, the ratio of propylene to ethylene can be adjusted by changing the dehydration catalysts to favor the production of acetol or acrolein: Acetol forms propylene, and acrolein forms ethylene. To overcome the fast deactivation of acid catalysts in glycerol dehydration, the hydrogenolysis and catalytic cracking reactions can be synchronized to convert glycerol into hydrocarbons using a combination of metal and acid catalysts. The single-step conversion of glycerol over a metal or bifunctional catalyst formed alcohols and paraffin. The highest selectivity for propylene production (approximately 76%) was obtained in a tandem process via the selective hydrogenolysis of glycerol to propanols over Pt/ZSM-5 catalysts followed by the catalytic dehydration/cracking of propanols to propylene over ZSM-5 catalysts at low temperatures (523 K). The selectivity for propylene was improved by increasing the Si/Al ratio of the ZSM-5 catalysts and the reaction time. Under these conditions, economically competitive crude glycerol (mainly mixtures of glycerol and methanol) can be used to synthesize light olefins (approximately 61% selectivity) with a long lifetime (∼500 h) in single-route reactions by increasing the cracking temperature to 773 K, which is suitable for practical methanol to propylene process.

Glycosylation reaction involving the coupling of a glycosyl donor with a glycosyl acceptor is one of the cornerstones of chemical preparation of pure glycans and glycoconjugates of biological relevance. Catalytic glycosylation of glycosyl ester donors and thioglycosides is an attractive but underexplored topic in carbohydrate chemistry. Herein, triflic imide (Tf 2 NH)catalyzed glycosylation of various O-, S-, and C-nucleophiles has been achieved using disarmed glycosyl ortho-isopropenylphenylacetates (GIPPAs) and ortho-isopropenylbenzyl thioglycosides as glycosylating agents. The reactions proceed under mild conditions to give the desired glycosides in good-to-excellent yields. Of particular note, the comparable reactivity for the αisomers and the β-ones of GIPPAs is observed. The mechanistic investigation demonstrates that the isopropenyl group is essential for the reaction and its preferential protonation triggers the reaction. This work provides another member to the arsenals of glycosyl ester and thioglycoside donors suitable for acid-catalyzed glycosylation to create various glycosidic bonds.

The first total synthesis of rebaudioside R has been achieved via two different approaches.

With cheap and easily available mixtures of steviol glycosides as starting materials, a practical method for steviol acquisition has been developed, on the basis of which a facile, diversity-oriented, and economic protocol for the synthesis of structurally defined steviol glycosides was established. The novel approach is featured by the highly efficient glycosylation of sterically hindered and acid-sensitive steviol via orchestrated application of Yu glycosylation, Schmidt glycosylation, and PTC glycosylation. Hence, these high-intensity sweeteners and potential lead compounds for drug development are now readily accessible.

An efficient approach to 6-deoxy-heptose constructs has been established by one-carbon homologation of the sugar chain of hexoses. The reaction features the formation of sugar-based α-substituted propanedinitriles and ensuing diverse oxidative transformations under mild reaction conditions that are compatible with a wide range of sugars bearing various functional/protecting groups. The applications of this method are demonstrated by a divergent assembly of Campylobacter jejuni strain 81-176 capsular trisaccharide repeating unit derivatives.