How cinchona alkaloid-derived primary amines control asymmetric electrophilic fluorination of cyclic ketones.

The origin of selectivity in the α-fluorination of cyclic ketones catalyzed by cinchona alkaloid-derived primary amines is determined with density functional calculations. The chair preference of a seven-membered ring at the fluorine transfer transition state is key in determining the sense and level of enantiofacial selectivity

Boron carboxylate catalysis of homoallylboration.

Boron tris(trifluoroacetate) is identified as the first effective catalyst for the homoallyl- and homocrotylboration of aldehydes by cyclopropylcarbinylboronates. NMR spectroscopic studies and theoretical calculations of key intermediates and transition states both suggest that a ligand-exchange mechanism, akin to our previously reported PhBCl2-promoted homoallylations, is operative. Our experimental and theoretical results also suggest that the catalytic activity of boron tris(trifluoroacetate) might originate from more facile catalytic turnover of the trifluoroacetate ligands (in agreement with DFT calculations) or from a lower propensity for formation of off-pathway reservoir intermediates (as observed by (1)H NMR). This work shows that carboxylates are viable catalytic ligands for homoallyl- and homocrotylations of carbonyl compounds and opens the door to the development of catalytic asymmetric versions of this transformation

Diagnostic yield at bronchoscopy samplying in bronchial carcinoma

published_or_final_versio

The relationship between sputum microbial load and inflammatory indices in bronchiectasis

published_or_final_versio

Presenting features of bronchial adenocarcinoma in Chinese patients

published_or_final_versio

Sputum elastase activity correlates with clinical parameters in steady state bronchiectasis

Conference Theme: Challenges to specialists in the 21st centurypublished_or_final_versio

Bronchoalveolar lavage is a safe and effective sampling modality for the diagnosis bronchial carcinoma

Conference Theme: Challenges to specialists in the 21st centurypublished_or_final_versio

Preliminary results of prevalence study of obstructive sleep apnoea in middle-aged Chinese in Hong Kong

published_or_final_versio

Helicobacter pylori sero-prevalence in asthma

published_or_final_versio

Ciliary central microtubular orientation in stable bronchiectasis

published_or_final_versio