Stable spiro-endoperoxides by sunlight-mediated photooxygenation of 1,2-O-alkylidene-5(E)-eno-5,6,8-trideoxy-alpha-D-xylo-oct-1,4-furano-7-uloses

Construction of quaternary stereocentres on carbohydrate scaffolds

This review describes a glimpse of the various strategies for constructing stereo-defined quaternary centres in densely functionalised carbohydrates moiety of structurally intriguing and biologically potent natural products and building blocks.

Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

The present review describes the current status of synthetic five and six-membered cyclic peroxides such as 1,2-dioxolanes, 1,2,4-trioxolanes (ozonides), 1,2-dioxanes, 1,2-dioxenes, 1,2,4-trioxanes, and 1,2,4,5-tetraoxanes. The literature from 2000 onwards is surveyed to provide an update on synthesis of cyclic peroxides. The indicated period of time is, on the whole, characterized by the development of new efficient and scale-up methods for the preparation of these cyclic compounds. It was shown that cyclic peroxides remain unchanged throughout the course of a wide range of fundamental organic reactions. Due to these properties, the molecular structures can be greatly modified to give peroxide ring-retaining products. The chemistry of cyclic peroxides has attracted considerable attention, because these compounds are used in medicine for the design of antimalarial, antihelminthic, and antitumor agents.

Synthesis, Characterization, and Thermokinetic Analysis of New Epoxy Sugar Derivative

The synthesis of 5,6-O-isopropylidene-1,2-O-(R)-trichloroethylidene-α-D-glucofuranose (compound1) and 5,6-O-isopropylidene-1,2-O-(R)-trichloroethylidene-3-O-(2′,3′-epoxypropan-1′-yl)-α-D-glucofuranose (compound2) was carried out. The synthesized compounds1and2were characterized by nuclear magnetic resonance (1H-NMR), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TG). The FTIR and1H NMR spectra showed that the epoxy group in compound2was attached by means of a nucleophilic substitution reaction. The activation energies for thermal degradation of compounds1and2were calculated from their TG data by using the Kissinger-Akahira-Sunose (KAS) and Tang methods.

The Newest Member of the Family of Chloralose: Synthesis ofβ-Ribochloralose and Some Derivatives

Treatment ofD-ribose with chloral in the presence of acid catalyst gives 1,2-O-(S)-trichloroethylidene-α-D-ribofuranose (1) (β-ribochloralose). Some derivatives of this product (1) were synthesized to be used as an intermediate in carbohydrate chemistry. Tricyclic orthoester structure (3, 77%) was obtained from the reaction of1with potassiumt-butoxide. This novel orthoester is expected to be useful as a glycosyl donor in the formations of new ribofuranoside units. 3-O-Methyl-ribochloralose (5) was synthesized in 75% yield via the methylation of1. 5-O-Tosyl-ribochloralose (6, 61%) was prepared with monotosylation reaction of1. Treatment of6with NaN3in DMF gives a 5-azido-5-deoxy-ribochloralose (7) in 77% yield. The azidosugar (7) was reduced to 5-amino-5-deoxy-ribochloralose (8, 72%) with triphenylphosphine according to Staudinger’s reduction procedure.

The Knoevenagel-Doebner reaction on 1,2-O-(2,2,2-trichloroethylidene) derivatives of D-gluco- and D-manno-furanose

The synthesis of new α,β-unsaturated furanuronic acid derivatives of α-gluco- (3), β-gluco- (6) and β-manno-chloraloses (9) via a convenient one pot procedure using the Knoevenagel-Doebner reaction approach are described. The dialdofuranose derivatives were reacted with malonic acid under Knoevenagel-Doebner reaction conditions and (E)-α,β-unsaturated furanuronic acid derivatives were obtained.

The sunny side of chemistry: green synthesis by solar light

The storage of solar energy is one of the main challenges in the near future. A rather unexploited way to fulfil this goal is the solar light induced formation of new chemical bonds, i.e. the synthesis of chemicals. Solar photons can be considered the ideal green reagents since they are costless and leave no residue in the reaction mixture. In many cases the solar radiation could be successfully used in place of toxic or expensive chemical reagents to overcome the activation energy in organic synthesis. In this perspective, the emerging trends on the use of solar light for green synthesis are summarized, highlighting the advantages of this photochemical method.