Asymmetric Intramolecular Oxa-Michael Reactions to Tetrahydrofurans/2<i>H</i>‑Pyrans Catalyzed by Primary–Secondary Diamines

The asymmetric intramolecular oxa-Michael reactions of α,β-unsaturated ketones have been achieved by using readily accessible primary–secondary diamines as the organocatalysts, giving the synthetically useful tetrahydrofurans/2<i>H</i>-pyrans in good yields and with high enantioselectivities (up to 90% ee)

Divergent Total Syntheses of (−)-Lycopladine D, (+)-Fawcettidine, and (+)-Lycoposerramine Q

Enantioselective total syntheses of (+)-fawcettidine and (+)-lycoposerramine Q as well as the first total synthesis of (−)-lycopladine D from a common intermediate have been accomplished by a divergent path. The common intermediate was derived from a Hajos–Parrish-like diketone by a stereoselective Birch reduction and a Suzuki coupling. The synthesis of (−)-lycopladine D featured an allylic oxidation and a biomimetic aminoketalization while the route to (+)-fawcettidine and (+)-lycoposerramine Q highlighted an oxidative rearrangement

Disturbance rejection of nonlinear boiler–turbine unit using high-order sliding mode observer

It is interesting and challenging to develop advanced controller for industrial boiler-turbine units due to their genuine nonlinearities, serious couplings among state variables, physical constraints imposed on control inputs, and in particular, various types of unknown uncertainties/disturbances. In this paper, a nonlinear disturbance rejection control method is investigated in a composite design manner for an oil-fired drum-type boiler-turbine unit. A baseline exponentially stable feedback controller is first designed, and then a high-order sliding mode observer is utilized to estimate and thus to compensate unknown lumped disturbances. It is shown that the obtained results for the boiler-turbine unit can be extended to a wide class of nonlinear systems. More interestingly, the finite-time stability of the closed-loop systems can be rendered in several cases. Finally, some numerical simulation scenarios are conducted on the boiler-turbine unit to demonstrate the claimed control performance

Divergent Total Syntheses of (−)-Lycopladine D, (+)-Fawcettidine, and (+)-Lycoposerramine Q

Enantioselective total syntheses of (+)-fawcettidine and (+)-lycoposerramine Q as well as the first total synthesis of (−)-lycopladine D from a common intermediate have been accomplished by a divergent path. The common intermediate was derived from a Hajos–Parrish-like diketone by a stereoselective Birch reduction and a Suzuki coupling. The synthesis of (−)-lycopladine D featured an allylic oxidation and a biomimetic aminoketalization while the route to (+)-fawcettidine and (+)-lycoposerramine Q highlighted an oxidative rearrangement

Asymmetric Robinson-Type Annulation Reaction between β‑Ketoamides and α,β-Unsaturated Ketones

Enantioselective Robinson-type annulation reaction between β-ketoamide and α,β-unsaturated ketone was developed by utilizing the amino acid derived primary–secondary diamine catalysts. The less reactive acyclic β-ketoamides employed as both electrophile and nucleophile are reported in this asymmetric tandem reaction. A number of chiral cyclohexenone derivatives containing an amide group were obtained in high yields and good selectivities

Safe Corridor to Access Clivus for Endoscopic Trans-Sphenoidal Surgery: A Radiological and Anatomical Study

<div><p>Purpose</p><p>Penetration of the clivus is required for surgical access of the brain stem. The endoscopic transclivus approach is a difficult procedure with high risk of injury to important neurovascular structures. We undertook a novel anatomical and radiological investigation to understand the structure of the clivus and neurovascular structures relevant to the extended trans-nasal trans-sphenoid procedure and determine a safe corridor for the penetration of the clivus.</p><p>Method</p><p>We examined the clivus region in the computed tomographic angiography (CTA) images of 220 adults, magnetic resonance (MR) images of 50 adults, and dry skull specimens of 10 adults. Multiplanar reconstruction (MPR) of the CT images was performed, and the anatomical features of the clivus were studied in the coronal, sagittal, and axial planes. The data from the images were used to determine the anatomical parameters of the clivus and neurovascular structures, such as the internal carotid artery and inferior petrosal sinus.</p><p>Results</p><p>The examination of the CTA and MR images of the enrolled subjects revealed that the thickness of the clivus helped determine the depth of the penetration, while the distance from the sagittal midline to the important neurovascular structures determined the width of the penetration. Further, data from the CTA and MR images were consistent with those retrieved from the examination of the cadaveric specimens.</p><p>Conclusion</p><p>Our findings provided certain pointers that may be useful in guiding the surgery such that inadvertent injury to vital structures is avoided and also provided supportive information for the choice of the appropriate endoscopic equipment.</p></div

Sulcus of the inferior petrosal sinus measured in the specimen.

<p><b>Line M:</b> Mid-sagittal line; <b>Curve S:</b> the medial boundary of the sulcus of the inferior petrosal sinus (safe corridor for fenestration of the posterior aspect of the clivus); <b>SPS:</b> sulcus of the inferior petrosal sinus; <b>D5:</b> Distance between the sulcus of the inferior petrosal sinus and the mid-sagittal line; <b>D6:</b> Distance between the sulcus of the inferior petrosal sinus and mid-sagittal line; <b>D7:</b> Distance between the sulcus of the inferior petrosal sinus and mid-sagittal line.</p

Location of trigeminal nerve in the MR image.

<p><b>9A</b>: Distance from the initial part of the trigeminal nerve to the mid-sagittal line; <b>Line M:</b> mid-sagittal line; <b>TN</b>: trigeminal nerve; <b>D8:</b> distance between the root of the trigeminal nerve and the mid-sagittal line. <b>9B: Line S:</b> Position of the axial plane in plane 8A; <b>PG:</b> the pituitary gland; <b>D9:</b> the distance between the axial plane through the root of trigeminal nerve and lowest, central point of the SF.</p