Mn(III)-Iodosylarene Porphyrins as an Active Oxidant in Oxidation Reactions: Synthesis, Characterization, and Reactivity Studies

Guo, Mian,Lee, Yong-Min,Seo, Mi Sook,Kwon, Yong-Ju,Li, Xiao-Xi,Ohta, Takehiro,Kim, Won-Suk,Sarangi, Ritimukta,Fukuzumi, Shunichi,Nam, Wonwoo American Chemical Society 2018 Inorganic Chemistry Vol.57 No.16

<P>Mn(III)-iodosylarene porphyrin adducts, [Mn(III)(ArIO)(Porp)]<SUP>+</SUP>, were synthesized by reacting electron-deficient Mn(III) porphyrin complexes with iodosylarene (ArIO) at −60 °C and characterized using various spectroscopic methods. The [Mn(III)(ArIO)(Porp)]<SUP>+</SUP> species were then investigated in the epoxidation of olefins under stoichiometric conditions. In the epoxidation of olefins by the Mn(III)-iodosylarene porphyrin species, epoxide was formed as the sole product with high chemoselectivities and stereoselectivities. For example, cyclohexene oxide was formed exclusively with trace amounts of allylic oxidation products; <I>cis</I>- and <I>trans</I>-stilbenes were oxidized to the corresponding <I>cis</I>- and <I>trans</I>-stilbene oxides, respectively. In the catalytic epoxidation of cyclohexene by an electron-deficient Mn(III) porphyrin complex and <SUP>s</SUP>PhIO at low temperature (e.g., −60 °C), the Mn(III)-iodosylarene porphyrin species was evidenced as the active oxidant that effects the olefin epoxidation to give epoxide as the product. However, at high temperature (e.g., 0 °C) or in the case of using an electron-rich manganese(III) porphyrin catalyst, allylic oxidation products, along with cyclohexene oxide, were yielded, indicating that the active oxidant(s) was not the Mn(III)-iodosylarene adduct but probably high-valent Mn-oxo species in the catalytic reactions. We also report the conversion of the Mn(III)-iodosylarene porphyrins to high-valent Mn-oxo porphyrins under various conditions, such as at high temperature, with electron-rich porphyrin ligand, and in the presence of base (OH<SUP>-</SUP>). The present study reports the first example of spectroscopically well-characterized Mn(III)-iodosylarene porphyrin species being an active oxidant in the stoichiometric and catalytic oxidation reactions. Other aspects, such as one oxidant versus multiple oxidants debate, also were discussed.</P><P>Mn(III)-iodosylarene porphyrin adducts, [Mn(III)(ArIO)(Porp)]<SUP>+</SUP>, were synthesized by reacting electron-deficient Mn(III) porphyrin complexes with iodosylarene (ArIO) and characterized using various spectroscopic methods. In the epoxidation of olefins by the Mn(III)-iodosylarene porphyrin species, epoxide was formed as the sole product with high chemoselectivities and stereoselectivities. The present study reports the first example of spectroscopically well-characterized Mn(III)-iodosylarene porphyrin species being an active oxidant in the stoichiometric and catalytic oxidation reactions.</P> [FIG OMISSION]</BR>

High-Spin Mn(V)-Oxo Intermediate in Nonheme Manganese Complex-Catalyzed Alkane Hydroxylation Reaction: Experimental and Theoretical Approach

Li, Xiao-Xi,Guo, Mian,Qiu, Bin,Cho, Kyung-Bin,Sun, Wei,Nam, Wonwoo American Chemical Society 2019 Inorganic Chemistry Vol.58 No.21

<P>Mononuclear nonheme manganese complexes are highly efficient catalysts in the catalytic oxidation of hydrocarbons by hydrogen peroxide in the presence of carboxylic acids. Although high-valent Mn(V)-oxo complexes have been proposed as the active oxidants that afford high regio-, stereo-, and enantioselectivities in the catalytic oxidation reactions, the importance of the spin state (e.g., <I>S</I> = 0 or 1) of the proposed Mn(V)-oxo species is an area that requires further study. In the present study, we have theoretically demonstrated that a mononuclear nonheme Mn(V)-oxo species with an <I>S</I> = 1 ground spin state is the active oxidant that effects the stereo- and enantioselective alkane hydroxylation reaction; it is noted that synthetic octahedral Mn(V)-oxo complexes, characterized spectroscopically and/or structurally, possess an <I>S</I> = 0 spin state and are sluggish oxidants. In an experimental approach, we have investigated the catalytic hydroxylation of alkanes by a mononuclear nonheme Mn(II) complex, [(<I>S</I>-PMB)Mn<SUP>II</SUP>]<SUP>2+</SUP>, and H<SUB>2</SUB>O<SUB>2</SUB> in the presence of carboxylic acids; alcohol is the major product with high stereo- and enantioselectivities. A synthetic Mn(IV)-oxo complex, [(<I>S</I>-PMB)Mn<SUP>IV</SUP>(O)]<SUP>2+</SUP>, is inactive in C-H bond activation reactions, ruling out the Mn(IV)-oxo species as an active oxidant. DFT calculations have shown that a Mn(V)-oxo species with an <I>S</I> = 1 spin state, [(<I>S</I>-PMB)Mn<SUP>V</SUP>(O)(OAc)]<SUP>2+</SUP>, is highly reactive and capable of oxygenating the C-H bond via oxygen rebound mechanism; we propose that the triplet spin state of the Mn(V)-oxo species results from the consequence of breaking the equatorial symmetry due to the binding of an equatorial oxygen from an acetate ligand. Thus, the present study reports that, different from the previously reported <I>S</I> = 0 Mn(V)-oxo species, Mn(V)-oxo species with a triplet ground spin state are highly reactive oxidants that are responsible for the regio-, stereo-, and enantioselectivities in the catalytic hydroxylation of alkanes by mononuclear nonheme manganese complexes and terminal oxidants.</P><P>It is theoretically demonstrated that a mononuclear nonheme Mn(V)-oxo species with an <I>S</I> = 1 ground spin state, [(<I>S</I>-PMB)Mn<SUP>V</SUP>(O)(OAc)]<SUP>2+</SUP>, is highly reactive and capable of oxygenating the C−H bond via oxygen rebound mechanism. Thus, it is proposed that a triplet spin state (<I>S</I> = 1) Mn(V)-oxo intermediate is generated as an active oxidant that is responsible for the regio-, stereo-, and enantioselectivities in the catalytic hydroxylation of alkanes by nonheme manganese catalysts and terminal oxidants.</P> [FIG OMISSION]</BR>

Comparison Different Methods of Intraoperative and Intraperitoneal Chemotherapy for Patients with Gastric Cancer: A Meta-analysis

Huang, Jin-Yu,Xu, Ying-Ying,Sun, Zhe,Zhu, Zhi,Song, Yong-Xi,Guo, Peng-Tao,You, Yi,Xu, Hui-Mian Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.9

Purpose: To investigate the efficacy and safety of intraperitoneal chemotherapy (IPC) for patients with gastric cancer and to compare effects between different regimens of IPC. Method: Randomized controlled trials comparing the effects of surgery plus intraperitoneal chemotherapy with surgery alone or comparing the efficacy between different regimens of intraperitoneal chemotherapy were searched for in Medline, Embase, Pubmed, the Cochrane Library and the Chinese BioMedical Disc and so on by two independent reviewers. After quality assessment and data extraction, data were pooled for meta-analysis using RevMan5.16 software. Tests of interaction were used to test for differences of effects among subgroups grouped according to different IPC regimens. Results: Fifteen RCTs with a total of 1713 patients with gastric cancer were included for quality assessment and data extraction. Ten studies were judged to be of fair quality and entered into meta-analysis. Hyperthermic intraoperative intraperitoneal chemotherapy (HR=0.60, P<0.01), hyperthermic intraoperative intraperitoneal chemotherapy plus postoperative intraperitoneal chemotherapy (HR=0.47, P<0.01) and normothermic intraoperative intraperitoneal chemotherapy (HR=0.70, P=0.01) were associated with a significant improvement in overall survival. Tests of interaction showed that hyperthermia and additional postoperative intraperitoneal chemotherapy did not impact on its effect. Further analysis revealed that intraperitoneal chemotherapy remarkably decrease the rate of postoperative hepatic metastasis by 73% (OR=0.27, 95% CI=0.12 to 0.67, P<0.01). However, intraperitoneal chemotherapy increased risks of marrow depression (OR=5.74, P<0.01), fever (OR=3.67, P=0.02) and intra-abdominal abscess (OR=3.57, P<0.01). Conclusion: The present meta-analysis demonstrates that hyperthermic intraoperative intraperitoneal chemotherapy and normothermic intraoperative intraperitoneal chemotherapy should be recommended to treat patients with gastric cancer because of improvement in overall survival. However, it is noteworthy that intraperitoneal chemotherapy can increase the risks of marrow depression, intra-abdominal abscesses, and fever.

Prediction of Pathologic Response to Neoadjuvant Chemoradiotherapy in Patients with Esophageal Squamous Cell Carcinoma Incorporating Hematological Biomarkers

Yingjia Wu,Jinbin Chen,Lei Zhao,Qiaoqiao Li,Jinhan Zhu,Hong Yang,Suping Guo,Mian Xi 대한암학회 2021 Cancer Research and Treatment Vol.53 No.1

Purpose This study aimed to develop a nomogram for predicting pathologic complete response (pCR) after neoadjuvant chemoradiotherapy (CRT) in patients with esophageal squamous cell carcinoma (ESCC) by integrating hematological biomarkers and clinicopathological characteristics. Materials and Methods Between 2003 and 2017, 306 ESCC patients who underwent neoadjuvant CRT followed by esophagectomy were analyzed. Besides clinicopathological factors, hematological parameters before, during, and after CRT were collected. Univariate and multivariate logistic regression analyses were performed to identify predictive factors for pCR. A nomogram model was built and internally validated. Results Absolute lymphocyte count (ALC), lymphocyte to monocyte ratio, albumin, hemoglobin, white blood cell, neutrophil, and platelet count generally declined, whereas neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) increased significantly following neoadjuvant CRT. After surgery, 124 patients (40.5%) achieved a pCR. The pCR group demonstrated significantly more favorable survival than the non-pCR group. On multivariate analysis, significant factors associated with pCR included sex, chemotherapy regimen, post-CRT endoscopic finding, pre-CRT NLR, ALC nadir during CRT, and post-CRT PLR, which were incorporated into the prediction model. The nomogram indicated good accuracy in predicting pCR, with a C-index of 0.75 (95% confidence interval, 0.71 to 0.78). Conclusion Female, chemotherapy regimen of cisplatin/vinorelbine, negative post-CRT endoscopic finding, pre-CRT NLR (≤ 2.1), ALC nadir during CRT (> 0.35×109/L), and post-CRT PLR (≤ 83.0) were significantly associated with pCR in ESCC patients treated with neoadjuvant CRT. A nomogram incorporating hematological biomarkers to predict pCR was developed and internally validated, showing good predictive performance.