Protected amino acids as a nonbonding source of chirality in induction of single-handed screw-sense to helical macromolecular catalysts.

Chiral nonbonding interaction with N-protected amino acid methyl esters used as chiral additives in achiral solvents allows dynamic induction of single-handed helical conformation in poly(quinoxaline-2,3-diyl)s (PQX) bearing only achiral substituents. Ac-l-Pro-OMe, for instance, allows induction of energy preference of 0.16 kJ mol-1 per monomer unit for the M-helical structure over the P-helix in t-butyl methyl ether (MTBE). With this new mode of screw-sense induction, homochiral screw-sense has been induced in virtually achiral poly(quinoxaline-2,3-diyl)s 1000-mer containing phosphine pendants (PQXphos). Use of PQXphos as a helically dynamic ligand along with Ac-Pro-OMe (l or d) as a chiral additive in MTBE allowed a highly enantioselective Suzuki-Miyaura coupling reaction with up to 95% enantiomeric excess.

Beyond 53% internal quantum efficiency in a AlGaN quantum well at 326 nm UVA emission and single-peak operation of UVA LED: publisher's note.

This publisher's note contains corrections to Opt. Lett.45, 495 (2020)OPLEDP0146-959210.1364/OL.376894.

Asymmetric Catalysis in Chiral Solvents: Chirality Transfer with Amplification of Homochirality through a Helical Macromolecular Scaffold.

Use of chiral solvents in asymmetric synthesis as a sole source of enantioselection remains largely unexplored in organic synthesis. We found that the use of a helical macromolecular catalyst of which helical chirality is dynamically formed in chiral solvents allowed several mechanistically different reactions to proceed with high enantioselectivity. In this system, the chirality of the solvent, such as limonene, induces a configurational imbalance to the helical macromolecular scaffold of the catalyst, and in turn to the reaction products through palladium-catalyzed asymmetric reactions including Suzuki-Miyaura cross-coupling (up to 98% ee), styrene hydrosilylation (up to 95% ee), and silaboration (up to 89% ee). Not only enantiomerically pure limonene but also limonene with low enantiomeric excesses induce single-handed helical structures with majority-rule-based amplification of homochirality. The helical conformation of the macromolecular catalyst was retained even in the absence of limonene in the solid state, enabling asymmetric cross-coupling in achiral solvent with high enantioselectivity.

Retrocecal hernia preoperatively diagnosed by computed tomography: A case report.

INTRODUCTION: Retrocecal hernia is a rare type of pericecal hernia. Because it is difficult to diagnose preoperatively, it is often treated with emergency operation. CASE PRESENTATION: An 83-year-old male patient experienced sudden abdominal pain. Marked small bowel dilatation and intestinal obstruction were detected by abdominal computed tomography (CT). An enhanced CT scan also revealed a trapped cluster of small bowel loops behind the cecum and ascending colon. We preoperatively diagnosed small bowel ileus as a result of retrocecal hernia. After conservative therapy with a long intestinal tube, an emergency operation was performed. During the surgery, a portion of the ileum was found to be incarcerated in the retrocecal fossa. Intestinal resection was not necessary because the incarcerated ileum appeared viable, and the orifice to the hernia was opened. The patient was discharged without postoperative complications. DISCUSSION: The diagnosis of retrocecal hernia can often be confirmed intraoperatively. This disease is identified based on a minimal error in rotation with incarceration behind the cecum during the final phase of descent and fixation of the right colon or failure of cecal and retroperitoneal fixation. Early preoperative diagnosis is important to prevent intestinal ischemia, necrosis, and perforation and to reduce resection rates. CONCLUSION: Early preoperative diagnosis is important to avoid resection of the small intestine. CT scans are useful for preoperative diagnosis in case of retrocecal hernia.

Synthesis and Catalytic Applications of a Triptycene-Based Monophosphine Ligand for Palladium-Mediated Organic Transformations.

1-Methoxy-8-(diphenylphosphino)triptycene (1), featuring high structural rigidity and steric bulkiness around the phosphine functionality, was synthesized as a new chiral monophosphine ligand for transition metal-catalyzed reactions. In the presence of 5-10 mol ppm (i.e., 0.0005-0.001 mol %) Pd(OAc)2 and 1 (2 equiv for Pd), Suzuki-Miyaura cross-coupling reactions of aryl bromides and arylboronic acids proceeded effectively under mild atmospheric conditions to give the corresponding biaryl compounds in a high yield. The single-crystal X-ray analysis of a Pd(II) complex of 1 revealed its coordination structure, in which two homochiral molecules form a dimer, suggesting that triptycene could provide a chiral environment for asymmetric organic transformations. In fact, optically active 1 obtained by optical resolution showed good enantioselectivity in the palladium-catalyzed asymmetric hydrosilylation of styrene, which represents, for the first time, the asymmetric catalytic activity of triptycene-based monophosphine ligands.

Accessory liver lobe attached to the gallbladder wall preoperatively detected by ultrasonography: A case report.

INTRODUCTION: An accessory liver lobe is a rare developmental abnormality, which is often not diagnosed preoperatively, and is usually detected incidentally during abdominal surgery. This condition is often asymptomatic; here, we report on a case where the accessory liver lobe was diagnosed preoperatively using ultrasonography. CASE PRESENTATION: A 59-year-old woman presented to our hospital with right upper abdominal pain. An abdominal ultrasonography indicated the presence of gallbladder debris and an accessory liver lobe. She underwent laparoscopic cholecystectomy and resection of the accessory liver lobe without any complications. DISCUSSION: An accessory liver lobe is a rare anomaly of the liver. It is typically asymptomatic and is detected incidentally during surgery or autopsy in most cases. However, we diagnosed the accessory liver lobe using ultrasonography. An accessory liver lobe can occasionally result in complications, such as bleeding, portal vein obstruction, or malignant transformation to hepatocellular carcinoma. CONCLUSION: An accessory liver lobe should be resected to prevent complications and malignant transformation. Ultrasonography is useful for preoperative diagnosis in cases with an accessory liver lobe.

Pressure-dependent helix inversion of poly(quinoxaline-2,3-diyl)s containing chiral side chains in non-aqueous solvents.

Poly(quinoxaline-2,3-diyl)s with chiral (S)-2-butoxymethyl side chains dissolved in 1,2-dichloroethane experience a reversible pressure-dependent helix inversion from P- to M-helical structures between 0.1 MPa and 200 MPa.

Solitary pelvic kidney encountered during laparoscopic colectomy.

We report a case of solitary pelvic kidney encountered during laparoscopic colectomy. A 55-year-old man was admitted to undergo laparoscopic colectomy for an early sigmoid colon cancer, which had been detected after a polypectomy. The kidneys were not clearly visualized in their normal position by ultrasonography. During the operation, anomalous vessels in the presacral space and a mass covered with fatty tissue were identified. We converted the operation to a mini-laparotomy, and on performing intraoperative ultrasonography a solitary pelvic kidney was detected. An anterior resection was performed without operative complications. Laparoscopic ultrasonography (LUS) and hand-assisted laparoscopic surgery (HALS) should be considered as feasible adjuvants, when difficult situations arise during laparoscopic colectomy. In case of uncertainty about anatomical orientation or identification, it is prudent to convert to open surgery thereby preventing intraoperative complications such as injury to anomalous vessels or the ureter.