Heterogeneous Copper-Catalyzed Cross-Coupling for Sustainable Synthesis of Chiral Allenes: Application to the Synthesis of Allenic Natural Products.

Classical Crabbé type SN 2' substitutions of propargylic substrates has served as one of the standard methods for the synthesis of allenes. However, the stereospecific version of this transformation often requires either stoichiometric amounts of organocopper reagents or special functional groups on the substrates, and the chirality transfer efficiency is also capricious. Herein, we report a sustainable methodology for the synthesis of diverse 1,3-di and tri-substituted allenes by using a simple and cheap cellulose supported heterogeneous nanocopper catalyst (MCC-Amp-Cu(I/II)). This approach represents the first example of heterogeneous catalysis for the synthesis of chiral allenes. High yields and excellent enantiospecificity (up to 97 % yield, 99 % ee) were achieved for a wide range of di- and tri-substituted allenes bearing various functional groups. It is worth noting that the applied heterogeneous catalyst could be recycled at least 5 times without any reduced reactivity. To demonstrate the synthetic utility of the developed protocol, we have applied it to the total synthesis of several chiral allenic natural products.

Sugar-Assisted Kinetic Resolutions in Metal/Chiral Amine Co-Catalyzed α-Allylations and [4+2] Cycloadditions: Highly Enantioselective Synthesis of Sugar and Chromane Derivatives.

Functionalized triose-, furanose and chromane-derivatives were synthesized by the titled reactions. The sugar-assisted kinetic resolution/C-C bond-forming cascade processes generate a functionalized sugar derivative with a quaternary stereocenter in a highly enantioselective fashion (up to >99 % ee) by using a simple combination of metal and chiral amine co-catalysts. Notably, the interplay between the chiral sugar substrate and the chiral amino acid derivative allowed for the construction of a functionalized sugar product with high enantioselectivity (up to 99 %) also when using a combination of racemic amine catalyst (0 % ee) and metal catalyst.

Anterior uterine incarceration complicated by placenta previa and placenta accreta spectrum disorder: a case report.

Background: Uterine incarceration is a rare obstetric complication that is always associated with retroversion and prone to misdiagnosis. Pelvic examination and imaging methods including ultrasound and magnetic resonance imaging (MRI) are used as the primary diagnostic tool. We present an asymptomatic anterior uterine incarceration complicated by placenta previa and placenta accreta spectrum (PAS) disorder, which could be diagnosed during the pregnancy periods, but was first diagnosed during the cesarean section (CS) and got the surgeons into trouble. Case Description: A 28-year-old woman, gravidity 4, parity 1, was hospitalized due to placenta previa and PAS disorder diagnosed by ultrasound and MRI at 35.6 weeks of gestation. She had not experienced any discomfort. Given her history of a previous CS, she underwent a well-prepared cesarean delivery for the termination of the pregnancy. The patient had a series of periodical ultrasound and MRI examinations in which placenta previa and placenta accreta were described in disregard of the abnormal location of cervix; consequently, interior uterine incarceration was first diagnosed during the surgery, which caused significant difficulties in the operation which lasted 3 hours and 21 minutes. The patient developed severe hemorrhaging and lost approximately 5,000 mL of blood. Fortunately, she delivered a health male infant weighing 3,440 grams with quite good Apgar scores. During the follow-up, maternal and child health was confirmed. Conclusions: With regard to patients who have undergone previous pelvic surgery, doctors need to pay close attention to the position of the cervix, the pelvic adhesion situation during the prenatal examination, and be on alert for uterine incarceration. Uterine incarceration can be accurately recognized by periodic sonography and MRI if the radiologist is aware of this unusual condition. We do suggest that special are must be taken to avoid unnecessary trauma by misdiagnosis because of lack of awareness.

Defense against oxidative stress in Caenorhabditis elegans by dark tea.

Dark tea, rich in nutricines including tea polyphenols and free amino acids, is a kind of post-fermented tea. The potential application of nutricines against oxidative damage and senescence, which drives animal health maintenance and disease prevention, has attracted considerable interest. In this study, the effect of dark tea and its effects on longevity and defense against oxidative stress was investigated in the Caenorhabditis elegans (C. elegans) model. Under normal conditions, dark tea extended the lifespan without significant impairment of propagation. It also improved the motility, alleviated the fat accumulation and apoptosis. Additionally, orally administered dark tea could significantly decrease the level of reactive oxygen species (ROS) and resulted in a superior lifespan in H2O2-induced oxidative stressed C. elegans. In antioxidant assays in vitro, dark tea was found to be rich in strong hydroxyl, DPPH and ABTS+ free radical scavenging capacity. Interestingly, mRNA sequence analyses further revealed that dark tea may catalyze intracellular relevant oxidative substrates and synthesize antioxidants through synthetic and metabolic pathways. These results suggest that dark tea is worth further exploration as a potential dietary supplement for the maintenance of animal health and the prevention of related diseases.

Efficient Heterogeneous Copper-Catalyzed Alder-Ene Reaction of Allenynamides to Pyrrolines.

Herein, we describe an efficient nanocopper-catalyzed Alder-ene reaction of allenynamides. The copper nanoparticles were immobilized on amino-functionalized microcrystalline cellulose. A solvent-controlled chemoselectivity of the reaction was observed, leading to the chemodivergent synthesis of pyrrolines (2,5-dihydropyrroles) and pyrroles. The heterogeneous copper catalyst exhibits high efficiency and good recyclability in the Alder-ene reaction, constituting a highly attractive catalytic system from an economical and environmental point of view.

Tuning the Sensitivity and Dynamic Range of Optical Oxygen Sensing Films by Blending Various Polymer Matrices.

In this work, eight different types of optical oxygen sensing films were prepared by impregnating indicator and matrix solution on the surface of a polypropylene microporous filter membrane. The polymer matrix of the sensing films was ethyl cellulose (EC), polymethyl methacrylate (PMMA), and their blends with different mixing ratios. Scanning electron microscopy (SEM), laser confocal microscopy, and fluorescence spectrometer were used to investigate the morphologies and optical properties of the sensing films. Phase delay measurements under different oxygen partial pressures (PO2) and temperatures were applied to investigate the analytical performances of the sensing film for gaseous O2 monitoring. Results show that the response time of all the sensing films was extremely fast. The sensitivities and dynamic ranges of the sensing films with the blended polymer matrix were separately decreased and increased as the EC/PMMA ratio decreased, and the S-V curve of the sensing films blended with equal content of EC and PMMA exhibited good linearity under different temperatures, showing a promising prospect in practical application.

Synergistic Catalysis: Highly Enantioselective Acetyl Aza-arene Addition to Enals.

A novel catalytic enantioselective methodology based on synergistic catalysis for the synthesis of chiral 2-acyl pyridines and pyrazines is reported. The strategy involves the metal-Lewis acid activation of acetyl aza-arenes and the secondary-amine activation of enals. The proposed mechanism is supported by DFT calculations.

Extended reverse dorsal metacarpal artery flap for coverage of finger defects distal to the proximal interphalangeal joint.

UNLABELLED: Finger reconstruction distal to the proximal interphalangeal (PIP) joint is a challenging task for hand surgeons. Although extended reverse dorsal metacarpal artery (RDMA) flaps were described for coverage of finger defects, reports on repairs beyond the PIP joint are limited. The occurrence of venous congestion of the flaps and their treatments require further clarification. METHODS: Extended RDMA flaps were used to cover the finger defects extending from the PIP joints to the fingertips in a series of 16 patients. The reconstructed fingers included the index, middle, ring, and little fingers; thumb reconstruction was not included in this study. The flap size ranged from 2.5×1.8 to 5×3 cm. A composite flap with a segment of tendon was applied for a complex reconstruction in 4 cases. Either superficial branch of radial nerve or dorsal branch of ulnar nerve was included in flap elevation because of its perineural vascular network contributing to the flap perfusion. The pivot point was located at the level of the middle point of the proximal phalanx, where the communicating branches between the proper palmar digital artery and the dorsal metacarpal artery exist. A teardrop skin pedicle was used to reduce the tension of the flap pedicle. RESULTS: All flaps totally survived except that 1 flap had epidermal loss later salvaged by secondary skin grafting. Venous congestion occurred in the distal part of 5 flaps and was effectively relieved after multiple subcutaneous heparin injections. Neither of the 2 cases of nerve repair resulted in significant improvement in sensation. All donor sites were primarily closed. CONCLUSIONS: Extended RDMA flaps can be effectively applied in the reconstruction of finger defects beyond PIP joint. Its advantages include a simple dissection, single-stage reconstruction, and preservation of digital artery and nerve. The donor site can be primarily closed if the flap width is less than 3 cm. Multiple subcutaneous heparin injection is a preferred solution in cases where venous congestion occurs in the flap.

[An experimental study on transplantation of frozen canine phalangeal joint allografts incorporated with autogenic bone marrow].

OBJECTIVE: To investigate the result of the transplantation of frozen canine phalangeal joint allografts perforated and incorporated with autogenic bone marrow. METHODS: A proximal interphalangeal joint defect of 1.5 cm was prepared at bilateral sides of twenty-four adult healthy out-bred dogs. Three different types of allografts were applied to repair the defects: fresh autogenic phalangeal joints (group A, n = 16), frozen phalangeal joint allografts perforated and incorporated with fresh autogenic bone marrow (group B, n = 16), and frozen phalangeal joint allografts (group C, n = 16). Radiographic and histological study were used to evaluate the survival of transplanted joints. The observation was done 1, 3, 6 and 12 months after operation respectively. RESULTS: Based on the radiographic and histological changes of the transplanted joints, the osteoarthropathy of transplanted canine phalangeal joints could be divided into 3 degrees: mild degeneration, moderate degeneration and severe degeneration. Mild degeneration was observed in group A from 3 to 12 months. Mild degeneration was also found in group B from 1 to 6 months, and the endochondral ossification was obvious within the drilled bony holes. However, some joints in group B underwent moderate degeneration 12 months after operation. Group C joints in the first month had moderate degeneration, which progressed to severe degeneration 3 months after operation. CONCLUSION: Transplantation of frozen canine phalangeal joint allografts perforated and incorporated with autogenic bone marrow can effectively delay the degeneration of transplanted osteoarticular allografts at the early and middle stage.