Chiral auxiliaries in polymer-supported organic synthesis

The use of chiral auxiliaries in polymer-supported organic synthesis is reviewed. In many of the examples presented, not only does the auxiliary serve as an element for inducing asymmetry into the synthesis, but it also functions as the linker for attaching the synthesis substrate to the polymer support. © 2003 Elsevier Ltd. All rights reserved.postprin

A polystyrene-supported triflating reagent for the synthesis of aryl triflates

An insoluble polystyrene-supported triflating reagent has been prepared by suspension co-polymerization of N-(4-vinylphenyl)trifluoromethanesulphonimide, styrene and the JandaJel ® cross-linker. This reagent, in the presence of triethylamine, allows for the efficient synthesis of aryl triflates from a wide range of phenols in a process that permits the desired product to be isolated from the reaction mixture in essentially pure form via several filtration and concentration operations. Adding to the utility of this reagent is its ability to be easily recovered, regenerated and reused. Both soluble and insoluble bifunctional polymers containing trialkylamine moieties in addition to triflimide groups were also prepared and examined as triflating reagents. Unfortunately these reagents afforded only modest yields of the desired products in representative reactions. Graphical Abstract. © 2004 Elsevier Ltd. All rights reserved.postprin

Arsonium ylides in organic synthesis

postprin

Childhood intussusception: 17-year experience at a tertiary referral centre in Hong Kong

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A prospective interventional study to examine the effect of a silver alloy and hydrogel--coated catheter on the incidence of catheter-associated urinary tract infection

published_or_final_versio

Microbiome preterm birth DREAM challenge: Crowdsourcing machine learning approaches to advance preterm birth research

Every year, 11% of infants are born preterm with significant health consequences, with the vaginal microbiome a risk factor for preterm birth. We crowdsource models to predict (1) preterm birth (PTB; <37 weeks) or (2) early preterm birth (ePTB; <32 weeks) from 9 vaginal microbiome studies representing 3,578 samples from 1,268 pregnant individuals, aggregated from public raw data via phylogenetic harmonization. The predictive models are validated on two independent unpublished datasets representing 331 samples from 148 pregnant individuals. The top-performing models (among 148 and 121 submissions from 318 teams) achieve area under the receiver operator characteristic (AUROC) curve scores of 0.69 and 0.87 predicting PTB and ePTB, respectively. Alpha diversity, VALENCIA community state types, and composition are important features in the top-performing models, most of which are tree-based methods. This work is a model for translation of microbiome data into clinically relevant predictive models and to better understand preterm birth

Multipolymer reaction system for selective aerobic alcohol oxidation: Simultaneous use of multiple different polymer-supported ligands

A multipolymer reaction system has been developed in which a water-soluble polymer-supported 2,2′-bipyridine group and a similarly immobilized TEMPO derivative are used as ligands for copper to effect the mild and selective aerobic oxidation of primary alcohols in acetonitrile- water solvent. In this reaction system, poly(ethylene glycol) monomethyl ether (molecular weight = 5000 Da) was used as the support for both the 2,2′-bipyridine and TEMPO moieties because of its solubility properties. The use of these functionalized polymers simultaneously in catalytic quantities allows for primary alcohols to be oxidized selectively to the corresponding aldehydes in an environmentally friendly manner. This is the first reported example of using two different polymer-supported ligands together to form an organometallic species capable of catalyzing an organic reaction. © 2007 American Chemical Society.link_to_subscribed_fulltex

Assessing the long term manometric outcomes in patients with previous laparoscopic anorectoplasty (LARP) and posterior sagittal anorectoplasty (PSARP)

Joint Scientific Session: Colorectal & Hepatobiliary Surgery - Free paper: no. S02

Evaluation of defecative function 10 years or longer after laparoscopic assisted anorectal pull-through for anorectal malformation

Free pape