Highly enantio- and diastereoselective construction of spirocyclic oxindoles via a palladium-catalyzed decarboxylative asymmetric [4 + 2] annulation strategy.

A palladium-catalyzed decarboxylative asymmetric [4 + 2] annulation of methyleneindolinones with a zwitterionic oxo-1,4-dipole intermediate was successfully developed to access spirocyclic oxindoles bearing two vicinal stereocenters in good yields with high diastereoselectivities and enantioselectivities. This strategy features a broad substrate scope (28 examples), allowing for efficient scale-up. Further selective transformation of the product and preliminary mechanistic studies were conducted.

Rhodium-Catalyzed Asymmetric Hydroboration/Cyclization of 1,6-Enynes Enabled by Spirosiladiphosphine Ligands: Constructing Chiral Five-Membered Rings with a Boron Handle.

A rhodium-catalyzed enantioselective hydroboration/cyclization reaction of 1,6-enynes is achieved by employing a spirosiladiphosphine ligand. The process allows the synthesis of five-membered hetero- and carbocycles bearing a boron handle with high levels of activity and selectivity. Various enynes and organoboranes (HBdan, HBpin, HBmp, and HBamm) have been accommodated, and enynes containing terminal alkynes have been integrated into the process for the first time. The high yields and selectivities of the transformation highlight the synthetic utility of these novel spirosiladiphosphine ligands.

Chiral spirosiladiphosphines: ligand development and applications in Rh-catalyzed asymmetric hydrosilylation/cyclization of 1,6-enynes with enhanced reactivity.

Spirodiphosphines have been successfully applied in various asymmetric catalytic transformations. However, controlling the coordinating conformations by the direct displacement of the spiro atom remains elusive. Herein, we report the application of Si-centered spirodiphosphine (Si-SDP) ligands in the enantioselective hydrosilylation/cyclization of 1,6-enynes. The Si-SDPs showed superior reactivity to existing C2-symmetric diphosphines, allowing the generation of a range of chiral pyrrolidines with high yields and enantioselectivity (up to 96% yield and 92% ee) at room temperature with low catalyst loading. The mechanistic observations were consistent with the modified Chalk-Harrod mechanism, and the high reactivity of Si-SDPs was further leveraged for the room-temperature Rh-catalyzed hydrosilylation of alkynes.

Clinical application of fiberoptic bronchoscope combined with visual laryngeal mask awake tracheal intubation technique: a case report.

We presented a case of successful awake endotracheal intubation in a patient with a giant goiter and severe tracheal stenosis. The patient had difficulty in airway management during the perioperative anesthesia due to tracheal deviation and stenosis caused by tumor compression. We applied a visual laryngeal mask combined with fiberoptic bronchoscope to visualize the whole procedure of endotracheal intubation, from visually assessing the glottic, subglottic, and the tracheal conditions, to evaluating the pressure of the tumor on the trachea and the maximum tracheal tube diameter that could be passed. During the entire process, the patient remained awake, maintained spontaneous breathing, and actively cooperated with the clinical staff. Hence, we demonstrated that this method is safe, effective, operable, and could be generalized as a form of endotracheal intubation for patients with known difficult airways.