Sökresultat

Filtyp

Din sökning på "*" gav 535696 sökträffar

Chiral Aldehydes by Ring Contraction of Pento- and Hexopyranoside Epoxides

The chiral aldehydes (-)-(2S,5S)- and (-)-(2S,5R)-2-[[[dimethyl( 1,1,2-trimethylpropyl)silyl]oxy]methyl]-5-methoxy-2,5-dihydrofuran-3-carbaldehyde (2 and 4) were synthesized in 60 and 15% yield, respectively, by lithium bromide induced rearrangement of 6-O-silylated methyl 2,3- and 3,4-anhydro-a- and -d-D-hexopyranosides, obtained in two steps from methyl α- and β-D-glucopyranoside. Rearrangement

Carbohydrate-Derived Chiral Furanosidic α,β-Unsaturated Aldehydes in Conjugate and Diels-Alder Addition Reactions. Steric Hindrance by the Anomeric Substituent

The title aldehydes (lr, 1s, 2, and 3) underwent virtually diastereospecific conjugate addition by lithium methylcyanocuprate. The bulkiness of the anomeric benzyloxy or methoxy groups direct the attacking nucleophile to the less hindered side of the furanosidic ring. The stereochemical outcome of the Diels-Alder additions of cyclopentadiene to lr and 1s was governed almost completely by the bulki

Evaluation of Decentralized Algorithms for Coordination of Autonomous Vehicles at Intersections

Connected Autonomous Vehicles (AVs) with Vehicle-to-Vehicle (V2V) communication are becoming an essential component of the transportation system. Self-driving cars have the potential to optimize the roads' traffic flow, fuel consumption and remove the possibility of human error and distractions. In these systems, all involved vehicles must be fully autonomous for maximum gain. However, a fully aut

A novel care guide for personalised palliative care – a national initiative for improved quality of care

BackgroundEven when palliative care is an integrated part of the healthcare system, the quality is still substandard for many patients and often initiated too late. There is a lack of structured guidelines for identifying and caring for patients; in particular for those with early palliative care needs. A care guide can act as a compass for best practice and support the care of patients throughout

Analogues of 1D-Myo-inositol 1,2,6-trisphosphate. Preparation of carboxymethyl and 2-hydroxyethyl phosphate derivatives

Acylation of 1D-myo-inositol 1,2,6-trisphosphate (α-trinositol) followed by alkylation of the phosphate groups with benzyl bromoacetate or 2-benzyloxyethyl iodide and deprotection provides a route to analogues with modified phosphate groups. The modifications made alter steric and ionisation properties but the possibility to participate in hydrogen bonding and ionic interaction is retained.

Application of the arbuzov reaction for the synthesis of phosphonate analogues of myo-inositol 1,2-bis- and 1,2,6-trisphosphates and methyl α-D-mannopyranoside 2,3,4-trisphosphate

The reaction of perbenzylated (±)-myo-inositol 1,2-bis- and 1,2,6-tris-phosphites with benzyl bromoacetate, followed by catalytic (Pd/C) hydrogenolysis affords (±)-myo-inositol 1,2-bis- and 1,2,6-tris(carboxymethylphosphonate). The same procedure is used for the synthesis methyl α-D-mannopyranoside 2,3,4-tris(carboxymethylphosphonate).

Synthesis of α-trinositol related analogues. Structure-activity (analgesic and anti-inflammatory) relationships

α-Trinositol analogues, including methyl ethers, deoxy, oxa and aza derivatives were prepared. The parent compound possesses weak analgesic and anti-inflammatory properties. Removal of the non-phosphorylated hydroxyls generates a compound devoid of analgesic activity but which retains the anti-inflammatory property of the parent compound. The protection of these hydroxyls as methyl ethers lends to

Facilitating an encounter with a new sexuality discourse : The role of civic communicators in building sexual health literacy among newly arrived migrants

Language and different sexual health discourses constitute barriers to the uptake of information on sexual and reproductive health and rights among migrants. Challenges remain with regards to the design and implementation of culturally appropriate programmes and interventions. This study explored the role of civic communicators in increasing access to sexual health information among migrants reset

Benzylidene protected bis-MPA : A convenient dendrimer building block

Benzylidene protected bis-MPA, 2,2-bis(hydroxymethyl)propanoic acid, was synthesised and evaluated as building block in the construction of dendrimers. It was found that the anhydride of benzylidene protected bis-MPA reacts with neopentylic alcohols to give high yields of acylated products. Purification is facilitated by the crystalline nature of most ester products. Deprotection by hydrogenolysis

A novel processing aid for polymer extrusion : Rheology and processing of polyethylene and hyperbranched polymer blends

The use of hyperbranched polymers (HBPs) as a processing aid for linear low density polyethylene (LLDPE) was investigated. Various generation (or pseudo-generation) HBPs were used which had either 16 carbon atom alkanes or a mixture of 20/22 carbon atom alkanes on the end groups. In addition, the degree of end group substitution was studied. Blends of up to 10% HBP content were mixed via extrusion