Helicobacter pylori is involved in gastritis, gastric and duodenal ulcers, gastric adenocarcinoma, and mucosa-associated lymphoid tissue lymphoma. Earlier studies already suggested a role for autoimmune phenomena in H. pylori-linked disease. We now report that lipopolysaccharides (LPS) of H. pylori express Lewis y, Lewis x, and H type I blood group structures similar to those commonly occurring...

We report a Lewis acid catalyzed reaction sequence involving a 1,2-shift and subsequent C–H insertion that gives monocyclic and fused bicyclic cyclopentenone products. This reaction sequence, which is initiated by treating b-hydroxy-a-diazo ketones with a Lewis acid, proceeds through vinyl cation intermediates that insert at non-activated gamma C–H bonds. This reaction represents an alternative...

The Lewis acid-base reaction between PbI2 and solvent molecules is popular in fabricating PbI2 films by a two-step method for making perovskite solar cells. Here, we control the microstructure of PbI2 films through modulating the Lewis acid-base reaction by adding a small amount of N-methyl pyrrolidone into PbI2/DMF solution. PbI2 films with excellent crystallinity and full coverage are fabrica...

The observed rate of reaction in the dysprosium triflate catalyzed aza-Piancatelli rearrangement is controlled by a key off-cycle binding between aniline and catalyst. Deconvoluting the role of these ancillary species greatly broadens our understanding of factors affecting the productive catalytic pathway. We demonstrate that the rate of reaction is controlled by initial competitive binding bet...

A rapid and efficient one-pot, four-component protocol towards the synthesis of polyhydroquinoline derivatives has been developed. The condensation of aldehyde, dimedone, ethyl acetoacetate and ammonium acetate in presence of stannous chloride was carried out under solvent free condition to synthesize a variety of polyhydroquinoline derivatives in good to excellent yields. Stannous chloride was...

This thesis deals with the development of new methods for efficient synthesis and analysis in asymmetric catalysis. It focuses on the preparation of chiral cyanohydrins by enantioselective addition of cyanide to prochiral aldehydes. The initial part of the thesis describes the development of a dual Lewis acid– Lewis base activation system for efficient synthesis of chiral O-acylated and Ocarbon...

A new intramolecular Lewis acid catalyzed hetero-Diels-Alder reaction of N-arylimines 5 with nonactivated olefins tethered to the 2-azadiene system was developed in order to prepare 1,2,3,4,4a,9,9a,lO-octahydroacridine derivatives 6. Both reactivity and cis/ trans selectivity of 6 were mainly dependent on the substitution pattern in the 3-position of the cyclization precursor 5. The type of Lew...

The limitation of hydroxamate ester as a chiral Lewis acid coordination moiety was first shown in an intermolecular reaction involving a radical addition and sequential allylation processes. Next, the effect of hydroxamate ester was studied in the cascade addition-cyclization-trapping reaction of substrates with a carbon-carbon triple bond as a radical acceptor. When substrates with a methacryl...

The condensation of acetone using anhydrous hydrogen chloride results after three weeks at room temperature, in a 1 5 % yield of phorone (4) and a 7 5 % yield of mesityl oxide (5). In the presence of one weight percent of the Lewis acid, aluminium chloride, the yield of 4 is increased to 3 9 % . An increase in the amount of the Lewis acid, aluminium chloride, to ten weight percent results in a ...