Remote proton elimination: C-H activation enabled by distal acidification.

Generally, the acidity of carbon-hydrogen bonds is most sensitive to functionality just one or two bonds away. Here, we present an approach to the formation of carbon-carbon σ bonds by remote proton elimination, a distinct mode of carbon-hydrogen activation enabled by distal acidification through five carbon-carbon bonds. Application of remote proton elimination to cyclodecyl cations unveiled an appealing method for the synthesis of decalins. The transformation is regioconvergent, proceeds without the need for a directing group or precious metal, and demonstrates exquisite site selectivity. An in-depth computational study illuminated the reaction mechanism. Additionally, we describe the complete stereoisomeric enrichment of the decalin products through epimerization mediated by hydrogen atom transfer.

Synthesis of Complex Tetracyclic Fused Scaffolds Enabled by (3 + 2) Cycloaddition.

We describe the single-step formation of complex tetracyclic fused scaffolds enabled by (3 + 2) cycloaddition of azomethine ylides. Various indoles, N-protecting groups, and amino acids are well tolerated. The products are obtained in a catalyst-free manner with moderate to excellent yield and high diastereoselectivity. Representing a new scaffold that is not yet found in nature, the construction of pyrrolidine-fused cyclohepta-, azepino-, or oxepinoindoles could be found valuable in the synthesis of new pseudo-natural products.

Chemical and Redox Noninnocence of Pentane-2,4-dione Bis(S-methylisothiosemicarbazone) in Cobalt Complexes and Their Application in Wacker-Type Oxidation.

Cobalt complexes with multiproton- and multielectron-responsive ligands are of interest for challenging catalytic transformations. The chemical and redox noninnocence of pentane-2,4-dione bis(S-methylisothiosemicarbazone) (PBIT) in a series of cobalt complexes has been studied by a range of methods, including spectroscopy [UV-vis, NMR, electron paramagnetic resonance (EPR), X-ray absorption spectroscopy (XAS)], cyclic voltammetry, X-ray diffraction, and density functional theory (DFT) calculations. Two complexes [CoIII(H2LSMe)I]I and [CoIII(LSMe)I2] were found to act as precatalysts in a Wacker-type oxidation of olefins using phenylsilane, the role of which was elucidated through isotopic labeling. Insights into the mechanism of the catalytic transformation as well as the substrate scope of this selective reaction are described, and the essential role of phenylsilane and the noninnocence of PBIT are disclosed. Among the several relevant species characterized was an unprecedented Co(III) complex with a dianionic diradical PBIT ligand ([CoIII(LSMe••)I]).

COMBINED CENTRAL RETINAL ARTERIAL AND VENOUS OCCLUSIONS DUE TO LEUKEMIC INFILTRATION.

PURPOSE: To report combined central arterial and venous occlusions secondary to bilateral leukemic interfascicular optic nerve infiltration in a 56-year-old man. This was the sole presentation of a relapse in T/myeloid mixed-phenotype acute leukemia after 5 months of remission. METHODS: Case report with clinical photography. RESULTS: A 56-year-old man reported to be in complete remission of T/myeloid mixed-phenotype acute leukemia presented with sudden painless loss of vision in his left eye. Fundoscopy showed unilateral severe optic disk swelling with characteristic findings of a central retinal vein occlusion, namely, intraretinal and preretinal hemorrhages and cotton-wool spots, as well as the features of a central retinal artery occlusion resulting in a pale, edematous retina and a characteristic cherry-red spot. Blood analysis, cerebrospinal fluid evaluation, and bone marrow analysis were performed in combination with medical imaging. No evidence of leukemic relapse was found. An optic nerve biopsy was indicated because of decompensation of the contralateral eye and ultimately confirmed leukemic infiltration. CONCLUSION: Regardless of no hematological and nonspecific imaging findings, optic nerve biopsy may be crucial for clinical decision-making in a patient with acute complete vision loss and a history of leukemia.

Reoperation for bleeding after cardiac surgery.

BACKGROUND: Postoperative cardio-surgical haemostatic management is centre-specific and experience-based, which leads to a variability in patient care. This study aimed to identify which postoperative haemostatic interventions may reduce the need for reoperation after cardiac surgery in adults. METHODS: A retrospective case-control study in a tertiary centre. Adult, elective, primary cardiac surgical patients were selected (n = 2098); cases (n = 42) were patients who underwent reoperation within 72 h after the initial surgery. Interventions administered to control surgical bleeding were compared for the need to re-operate using multiple logistic regression. RESULTS: Rate of cardiac surgical reoperation was 2% in the study population. Three variables were found to be associated with cardiac reoperation: preoperative administration of fresh frozen plasma (OR 5.45, CI 2.34-12.35), cumulative volume of chest tube drainage and cumulative count of packed red blood cells transfusion on ICU (OR 1.98, CI 1.56-2.51). CONCLUSION: No significant difference among specific types of postoperative haemostatic interventions was found between patients who needed reoperation and those who did not. Perioperative transfusion of fresh frozen plasma, postoperative transfusion of packed cells and cumulative volume of chest tube drainage were associated with reoperation after cardiac surgery. These variables could help predict the need for reoperation.

Chemoselective Alpha-Deuteration of Amides via Retro-ene Reaction.

A synthetically convenient approach for the direct α-deuteration of amides is reported. This mechanistically unusual process relies on a retro-ene-type process, triggered by the addition of deuterated dimethyl sulfoxide to a keteniminium intermediate, generated through electrophilic amide activation. The transformation displays broad functional-group tolerance and high deuterium incorporation.