Search results for "synthesis"

Enantioselective Synthesis of Cuparane Sesquiterpenes. Synthesis of (−)-Cuparene and (−)-δ-Cuparenol

1996

(−)-Cuparene and (−)-δ-cuparenol, two cuparane-type sesquiterpenoids, were synthesized from β-cyclogeraniol in 47% and 27% overall yield, respectively, using a Katsuki−Sharpless asymmetric epoxidat...

Metal-free electrochemical fluorodecarboxylation of aryloxyacetic acids to fluoromethyl aryl ethers

2020

Electrochemical decarboxylation of aryloxyacetic acids followed by fluorination provides easy access to fluoromethyl aryl ethers. This electrochemical fluorodecarboxylation offers a sustainable approach with electric current as traceless oxidant. Using Et3N·5HF as fluoride source and as supporting electrolyte, this simple electrosynthesis affords various fluoromethoxyarenes in yields up to 85%.

Heterogeneous vs Homogeneous Palladium Catalysts for Cross-Coupling Reactions

2012

A large number of immobilized-Pd-catalysts for cross-coupling reactions have been introduced in the last decade. Are the observed catalyzed reactions truly heterogeneous or are they homogeneous due to leached palladium? This account critically addresses the leaching issue by selectively referring to some of the newly developed catalytic systems in an attempt to evaluate said systems based on uniform criteria. The report is concluded by identifying the relevant chemical and structural challenges in the field.

Two chloride ions as a template in the formation of a cyclic hexaurea.

2006

Synthesis and radiosynthesis of N5-[18F]fluoroethyl-Pirenzepine and its metabolite N5-[18F]fluoroethyl-LS 75

2009

The well established M1 selective muscarinergic antagonist Pirenzepine 11-[2-(4-methyl-piperazin-1-yl)-acetyl]-5,11-dihydro-benzo[e]pyrido[3,2-b][1,4]diazepin-6-one (1) exhibits an unusual behaviour in vivo, which cannot be explained with M1 antagonism exclusively. One of the aspects discussed is a specific interaction with poly ADP-ribose polymerase (PARP-1). 1 undergoes metabolism to form LS 75 5,11-dihydro-benzo[e]pyrido[3,2-b][1,4]diazepin-6-one (2). In order to study deviations in Pirenzepine efficacy from pure M1 binding in vivo using PET, appropriate positron emitter labelled analogues of 1 and 2 were synthesised. Non-radioactive reference compounds 3 and 4 were tested for PARP-1 inh…

Enantioselective Synthesis of Unsymmetrical Benzoins from (S)-Mandelic Acid Enolate and Aromatic Aldehydes.

2004

The reaction of the lithium enolate of the 1,3-dioxolan-4-one derived from optically active (S)-mandelic acid and pivalaldehyde with aromatic aldehydes proceeds readily to give the corresponding aldol products in good yields and diastereoselectivities. Subsequent hydroxyl protection, basic hydrolysis of the dioxolanone, oxidative decarboxylation of the α-hydroxyacid moiety, and hydroxyl deprotection provides chiral unsymmetrical benzoins with high enantiomeric excesses.

Validation of the Tetracycline Regulatable Gene Expression System for the Study of the Pathogenesis of Infectious Disease

2011

Understanding the pathogenesis of infectious disease requires the examination and successful integration of parameters related to both microbial virulence and host responses. As a practical and powerful method to control microbial gene expression, including in vivo, the tetracycline-regulatable system has recently gained the favor of many investigative groups. However, some immunomodulatory effects of the tetracyclines, including doxycycline, could potentially limit its use to evaluate host responses during infection. Here we have used a well-established murine model of disseminated candidiasis, which is highly dependent on both the virulence displayed by the fungal cells and on the host im…

Tithonia oxfordiana, a new irregular echinoid associated with Jurassic seep deposits in south-east France

2011

The infaunal irregular echinoid, Tithonia oxfordiana, is described and compared to congeneric species previously described from Upper Jurassic and lowermost Cretaceous strata. This new species characterizes a monospecific echinoid assemblage, which occurs only in some places where deep-marine middle Oxfordian deposits are exposed in south-east France. Specimens are closely packed and clearly concentrated at the top of small carbonate chemoherms; a close connection of the echinoids with the emission of reduced chemicals, which were oxidized by chemoautotrophic bacteria, is highly probable. Based on general test shape and plate architecture, T. oxfordiana probably was a deposit feeder on chem…

Purification of a fetal bovine serum factor that inhibits DNA synthesis in chick embryo retinas

1992

Walking Children Through a Minefield: How Professionals Experience Exploring Adverse Childhood Experiences

2017

Understanding the challenges of professionals in addressing child adversity is key to improving the detection, protection, and care of exposed children. We aimed to synthesize findings from qualitative studies of professionals’ lived experience of addressing child adversity. Through a systematic search, we identified eight qualitative studies and synthesized them using metaethnography. We generated three themes, “feeling inadequate,” “fear of making it worse,” and “facing evil,” and one overarching metaphor, “walking children through a minefield.” The professionals felt that they lacked the means necessary to explore child adversity, that they were apprehensive of worsening the child’s situ…