Benzylation Reactions in DMF Lead to an Impurity Which Acts as an Organocatalyst Poison in Thiourea-Catalyzed Glycosylations

Catalytic pyrolysis and liquefaction behavior of microalgae for bio-oil production

Microalgae bio-oil production is related to the sustainable use of world energy in the future. In the present work, catalytic pyrolysis and liquefaction behavior of microalgae for bio-oil production were investigated. The results show that the rare earth compounds as catalysts contributed to significantly accelerating the pyrolysis of microalgae via reducing the activation energy of pyrolysis process. Ce(II)/HZSM-5 presented the optimal catalytic pyrolysis and liquefaction effects by helping cut the microalgae molecule chains. The maximum bio-oil yield amounted to 49.71 wt% at the catalyst concentration of 5 wt%. The chemical components of the Spirulina bio-oil were composed of carboxylic acids, ketones, olefins, amides, ethers, esters, and partially cyclic N-containing compounds. Although the combustion performances of the Spirulina bio-oil are worse than those of the diesel fuel, it is superior to the reported rice husk bio-oil, suggesting a promising potential application prospect.

Stereoselective organocatalyzed glycosylations - thiouracil, thioureas and monothiophthalimide act as Brønsted acid catalysts at low loadings

Thiouracil catalyzes stereoselective glycosylations with galactals in loadings as low as 0.1 mol%. It is proposed that in these glycosylations thiouracil, monothiophthalimide, and the previously reported catalyst, Schreiner's thiourea, do not operate via a double H-bonding mechanism but rather by Brønsted acid/base catalysis. In addition to the synthesis of 2-deoxyglycosides and glycoconjugates, we report the first organocatalytic synthesis of 1,1'-linked trehalose-type sugars.

The aryne Sommelet–Hauser rearrangement

An aryne induced transition-metal-free and mild Sommelet–Hauser rearrangement of tertiary benzylamines for the synthesis of α-aryl amino acid derivatives in moderate to good yields and with broad substrate scope is presented.

Methods for 2-Deoxyglycoside Synthesis

Deoxy-sugars often play a critical role in modulating the potency of many bioactive natural products. Accordingly, there has been sustained interest in methods for their synthesis over the past several decades. The focus of much of this work has been on developing new glycosylation reactions that permit the mild and selective construction of deoxyglycosides. This Review covers classical approaches to deoxyglycoside synthesis, as well as more recently developed chemistry that aims to control the selectivity of the reaction through rational design of the promoter. Where relevant, the application of this chemistry to natural product synthesis will also be described.

Dearomative [2,3] sigmatropic rearrangement of ammonium ylides followed by 1,4-elimination to form α-(ortho-vinylphenyl)amino acid esters

A base-induced dearomative [2,3] sigmatropic rearrangement followed by 1,4-elimination produced α-(ortho-vinylphenyl)amino acid esters.

Structural and mechanistic studies of the base-induced Sommelet–Hauser rearrangement of N-α-branched benzylic azetidine-2-carboxylic acid-derived ammonium salts

The base-induced Sommelet–Hauser rearrangement of N-α-branched benzylic azetidine-2-carboxylic acid ester-derived ammonium salts was demonstrated.