Lactose as an inexpensive starting material for the preparation of aldohexos-5-uloses: synthesis of L-ribo and D-lyxo derivatives

SUMMARY: Partially protected derivatives of L-ribo- and D-lyxo-aldohexos-5-ulose have been prepared starting from triacetonlactose dimethyl acetal derivatives. Key steps of the synthetic sequences are a) the synthesis of 4'-deoxy-4'-eno- and 6'-deoxy-5'-eno lactose derivatives, and b) the epoxidation-methanolysis of the above enol ethers to give 1,5-bis-glycopyranosides, masked form of the target 1,5-dicarbonyl hexoses

LACTOSE TO NATURALIZE TEXTILE DYES

Many natural dyes, for example carminic acid, are soluble in water. We present a simple strategy to naturalize synthetic azadyes through their linkage with lactose to induce their water solubility. The dyeing process of textile fibres then becomes possible in water without additives such as surfactants and mordants, which result in products that are difficult to eliminate. Glyco-azadyes (GADs) we are presenting here are obtained through a diether linker to bond the azadye and the sugar. Tinctorial tests were carried out with fabrics containing wool, polyester, cotton, nylon, and acetate. GADs were found to be multipurpose and capable of dyeing many fabrics efficiently under mild conditions

Efficient double glycoconjugation to naturalize high molecular weight disperse dyes

Commercially available Disperse Orange 29 (1a) and Disperse Red 1 (2a) were elaborated to glycoconjugated species, following a new version of a previously-described ‘naturalisation’ procedure. Glutamic acid was chosen to achieve a double glycoconjugation, which is essential to give to the original disperse dye a water solubility suitable for reaching optimal dyeing conditions. UV–vis plot of the ‘naturalised’ species showed negligible differences when compared to those of the commercial dye

measurement and comparison of reliability performance of photovoltaic power optimizers for energy production

Abstract Photovoltaic (PV) power optimizers are introduced in PV systems to improve their energetic productivity in presence of mismatching phenomena and not uniform operating conditions. Commercially available converters are characterized by different DC-DC topologies. A promising one is the boost topology with its different versions. It is characterized by its circuital simplicity, few devices and high efficiency values - necessary features for a Distributed Maximum Power Point Tracking (DMPPT) converter. PV power optimizer designs represent a challenging task since they operate in continuously changing operating conditions which strongly influence electronic component properties and thus the performance of complete converters. An aspect to carefully analyze in such applications is the thermal factor. In this paper, a necessity to have a suitable temperature monitoring system to avoid dangerous conditions is underlined In addition, another important requirement for a PV power optimizer is its reliability, since it can suggest a useful information on its diagnostic aspects, maintenance and investments. In fact, a reliable device requires less maintenance services, also improving the economic aspect. The evaluation of the electronic system reliability can be carried out using different reliability prediction models. In this paper, reliability indices, such as the Mean Time Between Failure (MTBF) or the Failure Rate of a Diode Rectification (DR) boost, are calculated using the evaluation of the Military Handbook 217F and Siemens SN29500 prediction models. With the reliability prediction results it has been possible to identify the most critical components of a DMPPT converter and a measurement setup has been developed in order to monitor the component stress level on the temperature, power, voltage, current, and energy in the DMPPT design phase avoiding the occurrence of a failure that might decrease the service life of the equipment

A new route for the synthesis of Streptococcus pneumoniae 19F and 19A capsular polysaccharide fragments avoiding the beta-mannosamine glycosylation step

SUMMARY The recently described (Carbohydr. Res. 2008, 43, 2545-2556) b-D-MaNAcp- (1→4)-b-D-Glcp thiophenyl glycosyl donor 3 was used in a-glycosylation reactions of OH-2 and OH-3 of the suitably protected p-MeO-benzyl a-L-rhamnopyranoside acceptors 7 and 8. The glycosylation of axial OH-2 of 7 took place in high yield (76%) and with good stereoselectivity (a/b = 3.4) leading to the protected trisaccharide a-11, corresponding to the repeating unit of Streptococcus pneumoniae 19F. The same reaction on equatorial OH-3 of acceptor 8 gave the trisaccharide a-15, constituent of the repeating unit of S. pneumoniae 19A, but in lower yield (41%) and without stereoselection (a/b = 1:1.3). Utilizing the introduced orthogonal protection of OH-1 and OH-4’’, the trisaccharide a-11 was transformed into a trisaccharide building block suitable for the synthesis of its phosphorylated oligomers

Synthesis of glycose carbamides and evaluation of the induction of erythroid differentiation of human erythroleukemic K562 cells

SUMMARY A series of carbamides derived from 1,2:5,6-di-O-isopropylidene-D-gluco- (1) and D-allofuranose (3) as well as their 5,6-O-deprotected analogues (2 and 4) and methyl 3,4-O-isopropylidene-alfa- and beta-D-galactopyranosides (5 and 6) have been prepared in order to evaluate their ability to induce erythroid differentiation of human erythroleukemic K562 cells. Twenty out of 51 carbamides tested exhibit an appreciable activity as inducers of erythroid differentiation and have been fully characterized and described

Toward the synthesis of fine chemicals from lactose: preparation of d-xylo and l-lyxo-aldohexos-5-ulose derivatives

SUMMARY The transformation of (5R)-2,6-di-O-benzyl-5-C-methoxy-β-d-galactopyranosyl-(1→4)-2,3:5,6-di-O-isopropylidene-aldehydo-d-glucose dimethyl acetal (8) into partially protected derivatives of d-xylo- and l-lyxo-aldohexos-5-ulose has been reported, applying appropriate epimerisation methods to its 3′-O- and 4′-O-protected alcoholic derivatives