Development of Clinical Risk Scores for Detection of COVID-19 in Suspected Patients During a Local Outbreak in China: A Retrospective Cohort Study.

Objectives: To develop and internally validate two clinical risk scores to detect coronavirus disease 2019 (COVID-19) during local outbreaks. Methods: Medical records were extracted for a retrospective cohort of 336 suspected patients admitted to Baodi hospital between 27 January to 20 February 2020. Multivariate logistic regression was applied to develop the risk-scoring models, which were internally validated using a 5-fold cross-validation method and Hosmer-Lemeshow (H-L) tests. Results: Fifty-six cases were diagnosed from the cohort. The first model was developed based on seven significant predictors, including age, close contact with confirmed/suspected cases, same location of exposure, temperature, leukocyte counts, radiological findings of pneumonia and bilateral involvement (the mean area under the receiver operating characteristic curve [AUC]:0.88, 95% CI: 0.84-0.93). The second model had the same predictors except leukocyte and radiological findings (AUC: 0.84, 95% CI: 0.78-0.89, Z = 2.56, p = 0.01). Both were internally validated using H-L tests and showed good calibration (both p > 0.10). Conclusion: Two clinical risk scores to detect COVID-19 in local outbreaks were developed with excellent predictive performances, using commonly measured clinical variables. Further external validations in new outbreaks are warranted.

Nickel-Catalyzed Cross-Coupling of Vinyl Dioxanones to Form Enantiomerically Enriched Cyclopropanes.

Under the conditions of nickel(0) catalysis, enantiomerically enriched vinyl dioxanones engage boroxines or B2(pin)2 in stereospecific cross-coupling to form diverse tetrasubstituted cyclopropanes bearing all-carbon quaternary stereocenters. The collective data corroborate a mechanism involving nickel(0)-mediated benzylic oxidative addition with inversion of stereochemistry followed by reversible olefin insertion to form a (cyclopropylcarbinyl)nickel complex, which upon reductive elimination releases the cyclopropane.

Total Synthesis and Stereochemical Assignment of Actinoranone.

The total synthesis of four actinoranone stereoisomers led to unambiguous assignment of relative and absolute stereochemistry of the natural product. Key features of the convergent, fully stereocontrolled route include the use of a Negishi carbozirconation/iodination, a Friedel-Crafts cyclization, a Felkin-controlled addition reaction, a Mitsunobu reaction, and a late-stage C-H oxidation.

Enantioselective Synthesis of Oxetanes Bearing All-Carbon Quaternary Stereocenters via Iridium-Catalyzed C-C Bond-Forming Transfer Hydrogenation.

Oxetanes bearing all-carbon quaternary stereocenters are readily prepared through the iridium-catalyzed anti-diastereo- and enantioselective C-C coupling of primary alcohols and isoprene oxide. Based on this methodology, an oxetane containing analogue of haloperidol was prepared. A related azetidine formation is also described.

Asymmetric Rh(I)-catalyzed intramolecular [3 + 2] cycloaddition of 1-yne-vinylcyclopropanes for bicyclo[3.3.0] compounds with a chiral quaternary carbon stereocenter and density functional theory study of the origins of enantioselectivity.

A highly enantioselective Rh(I)-catalyzed intramolecular [3 + 2] cycloaddition of 1-yne-VCPs to bicyclo[3.3.0] compounds with an all-carbon chiral quaternary stereocenter at the bridgehead carbon was developed. DFT calculations of the energy surface of the catalytic cycle (complexation, cyclopropane cleavage, alkyne insertion, and reductive elimination) of the asymmetric [3 + 2] cycloaddition reaction indicated that the rate- and stereo-determining step is the alkyne-insertion step. Analysis of the alkyne-insertion transition states revealed that the serious steric repulsion between the substituents in the alkyne moiety of the substrates and the rigid H(8)-BINAP backbone is responsible for not generating the disfavored [3 + 2] cycloadducts.