11 research outputs found

    The [2,3]-sigmatropic rearrangement of propargylic sulfonates to allenic sulfones and further applications to oxacycles and dihydrofuranones

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    [ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] The scope of [2,3]-sigmatropic rearrangement of propargylic sulfinates to allenic sulfones by silver catalysis was expanded. A series of new propargylic sulfinate esters was generated from a variety of aromatic and heteroaromatic sulfonyl chlorides and their rearrangement to allenic sulfones is reported. In addition, the synthesis of propargylic sulfinate esters containing electron-withdrawing benzenesulfonyl chlorides was optimized and reported. In the course of pursuing a Nazarov cyclization of allenyl vinyl ketones (AVK), we discovered multiple new reactions. Allenyl alcohols underwent an intramolecular cyclization to 2,5-dihydrofurans in the presence of Fetizon's reagent and this process was then optimized using silver fluoride. The methodology was expanded to synthesize higher membered oxacycles also. A tandem cyclization of hydroxypropargylic sulfinate esters to 2,5-hydrofurans was also developed. A new synthesis of a'-hydroxyenones was developed by the oxidation of a-allenyl alcohols with Cr (VI) regents and then extended to synthesize dihydrofuran- 3(2H)-ones by acid catalysis

    A Synthesis of Dihydrofuran-3(2<i>H</i>)‑ones

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    Treatment of readily available α′-hydroxyenones with a catalytic amount of strong acid in refluxing toluene affords the corresponding dihydrofuran-3­(2<i>H</i>)-ones in excellent yields via a formal 5-endo-trig cyclization

    Silver-Catalyzed Cyclization of Sulfonyl Allenes to Dihydrofurans

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    Treatment of α-hydroxy allenic sulfones with 10 mol % of silver fluoride in acetonitrile at ambient temperature furnished the corresponding 3-tosyl 2,5-dihydrofurans in excellent yields via a 5-<i>endo-trig</i> cyclization. The starting α-hydroxy allenic sulfones were prepared by lithiation of allenic sulfones and trapping with carbonyl compounds

    A Synthesis of Dihydrofuran-3(2<i>H</i>)‑ones

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    Treatment of readily available α′-hydroxyenones with a catalytic amount of strong acid in refluxing toluene affords the corresponding dihydrofuran-3­(2<i>H</i>)-ones in excellent yields via a formal 5-endo-trig cyclization

    Catalytic Generation of Vinylthionium Ions. (4 + 3)-Cycloadditions and Friedel–Crafts Alkylations

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    A 3-phenylsulfanyl-substituted allylic alcohol and an ester thereof were treated with Brønsted acids or a gold catalyst, respectively, to generate vinylthionium ions. These species react with dienes, primarily substituted furans, to give products of either (4 + 3)-cycloaddition or Friedel–Crafts alkylation. The results are rationalized on the basis of a stepwise mechanism in which the relative rates of ring closure versus proton loss in the intermediate σ-complex determine the course of the reaction

    CHAPTER 13: PARBOILING OF RICE

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    Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

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    © 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 licenseBackground: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit
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