Atom-economic and stereoselective catalytic synthesis of fully substituted enol esters/carbonates of amides in acyclic systems enabled by boron Lewis acid catalysis.

Carboacyloxylation of internal alkynes is emerging as a powerful and straightforward strategy for enol ester synthesis. However, the reported examples come with limitations, including the utilization of noble metal catalysts, the control of regio- and Z/E selectivity, and an application in the synthesis of enol carbonates. Herein, a boron Lewis acid-catalyzed intermolecular carboacyloxylation of ynamides with esters to access fully substituted acyclic enol esters in high yield with generally high Z/E selectivity (up to >96 : 4) is reported. Most importantly, readily available allylic carbonates are also compatible with this difunctionalization reaction, representing an atom-economic, catalytic and stereoselective protocol for the construction of acyclic ß,ß-disubstituted enol carbonates of amides for the first time. The application of the carboacyloxylation products to decarboxylative allylations provided a ready access to enantioenriched α-quaternary amides. Moreover, experimental studies and theoretical calculations were performed to illustrate the reaction mechanism and rationalize the stereochemistry.

Validation and effect of the NASA-TLX score on the assessment of the workload of pediatric robotic operations.

OBJECTIVE: The objective of the study was to assess the validity of the NASA-TLX score in rating the workload of pediatric robotic operations. METHODS: The workload of 230 pediatric gastrointestinal and thoracic robotic operations was rated using the NASA-TLX score. The difference between the high workload group and the low workload group in each subscale of the NASA-TLX score was analyzed. The correlation of each subscale with the total workload score in the high workload group and low workload group was also analyzed. A logistic regression analysis was subsequently conducted to assess the effects of different factors (sex, age, weight, procedure duration, procedure specialties, combined malformation and blood loss) on the workload. RESULTS: The average NASA-TLX score was 56.5 ± 5.1 for the total group, 56.9 ± 5.0 for the gastrointestinal group and 54.6 ± 4.8 for the thoracic group, p = 0.007. The score of the high workload group was 62.7 ± 3.2, while it was 50.6 ± 2.7 for the low workload group (p < 0.001). The score on each subscale was also significantly different between the high and low workload groups. In the high workload group, a stronger correlation was observed between the total score and TD and Fr and a lower correlation with MD and Pe. In the low workload group, all six subscales showed a moderate correlation with the total score. A multivariate logistic regression analysis revealed that the procedure duration was an independent influencing factor for a higher workload score. CONCLUSIONS: NASA-TLX is a valid tool to rate the surgeon's workload in pediatric robotic surgery. A longer operative time contributes to a higher workload.

Chirality Transfer in Rhodium(I)-Catalyzed [3 + 2]-Cycloaddition of Vinyl Aziridines and Oxime Ethers: Atom-Economical Synthesis of Chiral Imidazolidines.

A highly efficient and stereoselective synthesis of enantioenriched imidazolidines by rhodium-catalyzed intermolecular [3 + 2] cycloaddition reaction of chiral vinyl aziridines and oxime ethers has been successfully developed. Notably, both aldoximes and ketoximes are suitable substrates to afford the corresponding chiral imidazolidines in high yields with good stereoselectivity. This transformation represents an unprecedented example that utilizes ketimine derivatives as an aza-[2C]-component in cycloadditions of vinyl aziridines.

Rhodium(I)-Catalyzed Intermolecular Aza-[4+3] Cycloaddition of Vinyl Aziridines and Dienes: Atom-Economical Synthesis of Enantiomerically Enriched Functionalized Azepines.

A new synthetic application of vinyl aziridines as N-containing three-atom components in a rhodium-catalyzed [4+3] cycloaddition reaction is described. The reaction proceeds well with various silyl dienol ethers and vinyl aziridines, and enables the efficient synthesis of highly functionalized azepines in an enantioselective manner with net inversion of absolute configuration. The salient features of the transformation include the use of readily available substrates, high selectivity, and mild reaction conditions, as well as the versatile functionalization of the products.

An atom-economic synthesis of bicyclo[3.1.0]hexanes by rhodium N-heterocyclic carbene-catalyzed diastereoselective tandem hetero-[5+2] cycloaddition/Claisen rearrangement reaction of vinylic oxiranes with alkynes.

The first synthetic application of a vinylic oxirane as a heteroatom-containing five-atom component in transition-metal-catalyzed cycloaddition reactions is reported. A new, efficient, diastereoselective tandem intramolecular hetero-[5+2] cycloaddition/Claisen rearrangement of vinylic oxirane-alkyne substrates that uses a rhodium NHC complex and provides strategically novel, atom-economic, regiospecific, and diastereoselective access to [3.1.0] bicyclic products has been developed.