The disaccharide donor O-[2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl)-(1→4)-3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-α,β-d-glucopyranosyl] trichloroacetimidate (7) was prepared by reacting O-(2,3,4,6-tetra-O-acetyl-α-d-galactopyranosyl) trichloroacetimidate with tert-butyldimethylsilyl ...

The lacto-N-neotetraose tetrasaccharide was synthesized on a new dendrimeric support, based on polyethylene glycol. Starting from 1-thio-β-d-lactose, the trisaccharide (2-acetamido-2-deoxy-β-d-glucopyranosyl)-(1 → 3)-O-β-d-galactopyranosyl-(1 → 4)-1-thio-β-d-glucopyranose was obtained usin...

The discovery of innovative methods that offer new capabilities for obtaining individual oligosaccharides from human milk will help to improve understanding their roles and boost practical applications. The total chemical synthesis of lacto-N-neotetraose (LNnT) has been completed using both line...

A two-carbon homologation-amination technology of aldehydes is described. Key steps involve the Michael-type addition of a nitrogen nucleophile (benzylamine, trimethylsilylazide, potassium phtalimide) to a 2-alkenyl N-methylthiazolium salt obtained by olefination of the aldehyde with the phospho...

Addition of [(dimethylphenylsilyl)methyl]magnesium chloride to 6-benzylimino-6-deoxy-1,2;3,4-di-O-isopropylidene-α-D-galactopyranose mediated by Ce(III)Cl3 or CuI/BF3·Et2O proceeds with complete syn- or anti-diastereoselectivity, respectively, to afford highly chiral precursors of destomic aci...

A new and stereoselective route to the aminoglycoside components of the antibiotics lincomycin and clindamycin is presented. The key step involves diastereoselective introduction of the amino group at C-6 of d-galactose by (3,3)-sigmatropic rearrangements of the corresponding allylic (Z)-trifluo...

The syntheses of 6-amino-6-deoxyheptopyranurononitriles related to lincosamine by cyano-amination of 1,2:3,4-di-O-isopropylidene-α-d-galacto-hexodialdo-1,5-pyranose (2) is reported. The procedure described allowed direct cyano-amination in good yield under mild conditions. The high diastereofac...

Reaction of ketone 3 with dichloromethyllithium gave a unique branched-chain dichloromethyl sugar 7 whose structure was ascertained by X-ray crystallography. Transformation of 7 in seven steps, involving the key-intermediate α-azido-aldehyde 9, afforded the protected lincosamine analogue 14.

A general method for the synthesis of 6-position modified lincosamines via stereospecific nucleophilic addition to readily available galactose 6-nitrone has been developed. A new route for the stereospecific installation of thioalkyl groups at the 1-position was also developed. These methods all...

Arsenic is a ubiquitous toxic metalloid abundant in Earth’s crust. It is of major concern with respect to its increased accumulation in soils, in the food chain, or in drinking water. This chapter will focus on recent progress on the mechanisms of its uptake, toxicity, and detoxification in mic...

Arsenic (As), being a metalloid, is well known for its versatile applications to mankind. Arsenic is coined by USEPA as the number one carcinogen. The human body can metabolize arsenic into different forms after intake via water, soils, and food as well as by inhalation. Due to lack of instrumen...

The methylation reaction of arsenic trioxide conducted at 37 °C and pH 7.0 for 24 h using hydrophobic methylated vitamin B12, (methyl) (aquo) heptamethylcobyrinate perchlorate, CH3B12 ester, as a methyl donor in the presence of reduced glutathione (GSH) yielded monomethylarsonous acid (MMA), di...

Seafood, including finfish, shellfish, and seaweed, is the largest contributor to arsenic (As) exposure in many human populations. In contrast to the predominance of inorganic As in water and many terrestrial foods, As in marine-derived foods is present primarily in the form of organic compounds...

Animal studies have shown that chemical carcinogenesis consists of a three-stage process: initiation, promotion, and progression. However, because of the lack of a suitable tissue model, the molecular mechanisms of cell-cell interactions involved in those processes remain unclear. We have establ...

Arsenic species and a possible source of methylated arsenic in a Panax Notoginseng (PN) medicinal plant were explored to further understand the change of inorganic arsenic to the less toxic methylated form to minimize the health risks associated with its medicinal use. Arsenic speciation in PN f...

The host molecule 2,7-dimethyltricyclo[4.3.1.03,8]undecane-syn-2,syn-7-diol 1 is known to form two different structural types of lattice inclusion compound dependent on the guest molecule chosen. Guests, including 1,2-dichlorobenzene 2, have now been predicted which result in the formation of bo...

A synthetic route to 6,6-dimethyltricyclo[5.4.0.02,8]undecane-2,9-diol, a key precursor to (ent-)longipinane-type sesquiterpenoids, is described. This unique core common to (ent-)longipinanes was constructed using two types of intramolecular radical cyclization reactions, namely, intramolecular ...

The possibility that various chemical treatments may enhance the corrosion resistance of a magnesium alloy (containing rare earths, WE43 alloy) has been investigated. Cerium(III) conversion coatings and silanic coatings, with and without acid pickling, were tested in 0.1 N Na2SO4 solution. Silan...

The high-speed determination of hydrogen, magnesium and calcium ions by ion chromatography (IC) is demonstrated on a monolithic octadecyl-boned silica (ODS) column coated with lithium dodecylsulfate (Li-DS). This stationary phase, when used in conjunction with a 2 mM ethylenediamine and 0.1 mM L...

Using combined semiempirical quantum mechanics and molecular mechanics (QM/MM) and ab initio self-consistent reaction field (SCRF) calculations, we determined that a low-barrier hydrogen bond (LBHB) is formed when the mechanism-based substrate 8-methylpterin binds to dihydrofolate reductase (DHF...