No abstract

The synthesis of strained polycyclic systems from readily available precursors with a minimum number of steps and with regio- and stereochemical control constitutes an important synthetic challenge. Herein, we report a tandem reaction comprising Co-TMTU (tetramethyl thiourea)-catalyzed Pauson-Khand (PK) and 6π-electrocyclization reactions for the formation of the highly strained core of presilphiperfolanols. The developed chemistry has been applied to the total syntheses of 4-epi-presilphiperfolan-8-ol and 7-epi-presilphiperfolan-1-ol.

We investigated the epidemiological and clinical characteristics deaths from road traffic injury (RTI) in Beijing, and provided evidence useful for the prevention of fatal traffic trauma and for the treatment of traffic-related injuries. We retrospectively reviewed death cases provided by the Beijing Red Cross Emergency Center on road traffic injury deaths from 2008 to 2017. We analyzed population characteristics, time distribution, distribution of transportation modes, intervals to death, locations and injured body parts. From 2008 to 2017, there were 3327 deaths from RTI recorded by the Beijing Red Cross Emergency Center, with mainly males among these deaths. The average age at death was 46.19 ± 17.43 years old (46.19, 0.43–100.24). In accidents with more detail recorded, pedestrians and people using nonmotorized transportation modes suffered the most fatalities (664/968, 68.60%). The most commonly injured body parts were the head (2569/3327, 77.22%), followed by the chest (180/3327, 5.41%), abdomen (130/3327, 3.91%), lower extremities (68/3327, 2.04%), pelvis (67/3327, 2.01%), spinal cord (31/3327, 0.93%), and upper extremities (26/3327, 0.78%). Burns accounted for 0.96% (32/3327), and unknown body parts were affected in 11.28% (365/3327). The average time interval from injury to death was 36.90 ± 89.57 h (36.90, 0–720); 46.7% (1554/3327) died within 10 minutes after injury; 9.02% (300/3327) died between 10 min and 1 hour; 30.33% (1009/3327) died between 1 hour and 3 days; 13.95% (464/3327) died between 3 and 30 days. In Beijing, RTI is a significant cause of preventable death, particularly among pedestrians and users of non-motorized vehicles. Head trauma was the most lethal cause of RTI deaths. Our findings suggested that interventions to prevent collisions and reduce injuries, and improved trauma treatment process and trauma rescue system could address a certain proportion of avoidable RTI deaths.

Euphorikanin A is a diterpenoid possessing a highly congested and unprecedented 5/6/7/3-fused tetracyclic ring skeleton.

An efficient palladium-catalyzed decarboxylative cycloaddition process of vinyl cyclic carbonates and vinyloxazolidinones for the synthesis of highly substituted δ-lactone and δ-lactam derivatives was developed. This protocol exhibits several unique characteristics, including broad substrate scope, good functional group tolerance, and operational convenience, which enables a regioselective access to a variety of lactone and lactam scaffolds in moderate to good yield. The redox-neutral catalytic system promotes formation of substituted scaffolds with in situ generation of a cyclic tetra-substituted double bond functionality.

Background: We aimed to describe and analyze the pre-hospital emergency medical service (EMS) in Beijing and provide information for the government and medical institutions to optimize EMS. Methods: We collected all pre-hospital emergency data in Beijing from 2008 to 2017. The chief complaint in each case was classified according to the Medical Priority Dispatch System (MPDS). The sites’ administrative districts were determined through geo-encoding of addresses and then classified into four functional regions. We analyzed the demand for EMS, emergency response times (ERT), and disease spectrum for Beijing as a whole, and for each functional region. Results: A total of 4,192,870 pre-hospital EMS cases met the inclusion criteria, with a significant increase (P < 0.001) of 51.60% from 2008 to 2017. EMS demand was positively associated with population (r = 0.946, P < 0.001). The pre-hospital EMS demand rate was 1907.05 in 2008 and 2172.23 in 2017 per 100,000, with no significant change (P = 0.57). ERT increased significantly (P = 0.001), from 19.18 min in 2008 to 24.51 min in 2016. According to MPDS classifications, the demand for pre-hospital care increased for 14 diseases, remained stable for 19, and decreased for only 1 disease. Cases of injury-related disease increased significantly from approximately 90,000 in 2017, accounting for 20% of all pre-hospital EMS cases, and the demand rate decreased in the core region but increased in the sub-urban regions. Cases of heart problems and stroke/transient ischemic attack also increased significantly in the four functional regions, with the highest demand rate in the Core Functional Region. Conclusions: More resources and effort should be devoted to pre-hospital EMS according to the increased pre-hospital EMS demand and prolonged ERT in Beijing over our 10-year study period. Changes in disease spectrum and differences between functional regions should also be considered.

Here, we report a practical and reliable methodology to direct construction of tri- and tetrasubstituted olefins bearing an allylic amine, with the concomitant construction of the sterically congested quaternary stereocenter through stereoselective palladium-catalyzed cascade decarboxylation of vinyloxazolidinones.

Olefins play a vital role in the fields of bioscience, medicine, and chemistry. Stereo-defined olefins are important resource in both chemical laboratory and industry. Using a palladium-catalyzed decarboxylative transformation of vinyl cyclic carbonates, we have developed an efficient and reliable method for the direct construction of highly substituted olefins with the concomitant formation of a new Csp 3 -Csp 3 bond. The desired olefins could be generated in reasonable yields with good stereoselectivities, in contrast to the existing methods, which are usually nonstereoselective. The palladium-catalyzed decarboxylative transformation will undoubtedly provide new synthetic routes for the formation of multi-substituted allylic scaffolds.[a] L. Scheme 2. Scope with 1,3-dicarbonyl partners. Reaction conditions: 1 a (0.1 mmol), Pd catalyst (5 mol%), Ligand (8 mol%), stirring in DCM stirred at 30°C for 4 h.