Facile method for trimethylsilylation of alcohols using hexamethyldisilazane and ammonium thiocyanate under neutral conditions

A highly efficient method for trimethylsilylation of primary, secondary, tertiary, allylic, and a variety of sugar-derived alcohols using hexamethyldisilazane in the presence of a catalytic amount of ammonium thiocyanate under neutral conditions is reported

Oxidative Deselenization of Selenocysteine: Applications for Programmed Ligation at Serine

Despite the unique chemical properties of selenocysteine (Sec), ligation at Sec is an under‐utilized methodology for protein synthesis. We describe herein an unprecedented protocol for the conversion of Sec to serine (Ser) in a single, high‐yielding step. When coupled with ligation at Sec, this transformation provides a new approach to programmed ligations at Ser residues. This new reaction is compatible with a wide range of functionality, including the presence of unprotected amino acid side chains and appended glycans. The utility of the methodology is demonstrated in the rapid synthesis of complex glycopeptide fragments of the epithelial glycoproteins MUC5AC and MUC4 and through the total synthesis of the structured, cysteine (Cys)‐free protein eglin C

Chemical Ubiquitination for Decrypting a Cellular Code

The modification of proteins with ubiquitin (Ub) is an important regulator of eukaryotic biology and deleterious perturbation of this process is widely linked to the onset of various diseases. The regulatory capacity of the Ub signal is high and, in part, arises from the capability of Ub to be enzymatically polymerised to form polyubiquitin (polyUb) chains of eight different linkage types. These distinct polyUb topologies can then be site-specifically conjugated to substrate proteins to elicit a number of cellular outcomes. Therefore, to further elucidate the biological significance of substrate ubiquitination, methodologies that allow the production of defined polyUb species, and substrate proteins that are site-specifically modified with them, are essential to progress our understanding. Many chemically inspired methods have recently emerged which fulfil many of the criteria necessary for achieving deeper insight into Ub biology. With a view to providing immediate impact in traditional biology research labs, the aim of this review is to provide an overview of the techniques that are available for preparing Ub conjugates and polyUb chains with focus on approaches that use recombinant protein building blocks. These approaches either produce a native isopeptide, or analogue thereof, that can be hydrolysable or non-hydrolysable by deubiquitinases. The most significant biological insights that have already been garnered using such approaches will also be summarized

The intramolecular conjugate addition of benzylamine to a D-glucose derived α,β-unsaturated ester: an efficient synthesis of trihydroxylated pyrrolidine alkaloids as potential glycosidase inhibitors

A short and efficient synthesis of 1,4,5-trideoxy-1,4-imino-l-xylo-hexitol 2a and 1,4,5-trideoxy-1,4-imino-D-arabino-hexitol 2b is reported using the intramolecular conjugate addition of in situ generated benzylamine to the α,β-unsaturated ester 4, derived from D-glucose, as the key step

Rhodium carbenoid induced [1, 2]-migration in L-lyxo-configurated α-diazo-β-keto ester: synthesis of a new griseolic acid analogue

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An efficient synthesis of D-erythro- and D-threo-sphingosine from D-glucose: olefin cross-metathesis approach

The D-erythro- and D-threo-sphingosine were synthesized via E-selective olefin cross-metathesis using a D-glucose-derived building block and long-chain terminal alkene

Synthesis of (-)-lentiginosine, its 8a-epimer and dihydroxylated pyrrolizidine alkaloid from D-glucose

The D-glucose derived α,β-unsaturated ester 5 on 1,2-acetonide deprotection; oxidative diol cleavage followed by treatment with N-benzylamine in the presence of NaBH3CN undergoes reductive amination; a concomitant intramolecular conjugate addition reaction leading to the formation of dihydroxypyrrolidine-ester 6a; monohydroxypyrrolidine-γ-lactone 6b. Intermediates 6a and 6b were efficiently converted to (−)-lentiginosine 3a, its 8a-epimer 3b, pyrrolizidine azasugar 4 in good overall yield