Visible-Light-Mediated Activation of Remote C(sp3)-H Bonds by Carbon-Centered Biradical via Intramolecular 1,5- or 1,6-Hydrogen Atom Transfer.

In this study, we introduce a novel intramolecular hydrogen atom transfer (HAT) reaction that efficiently yields azetidine, oxetane, and indoline derivatives through a mechanism resembling the carbon analogue of the Norrish-Yang reaction. This process is facilitated by excited triplet-state carbon-centered biradicals, enabling the 1,5-HAT reaction by suppressing the critical 1,4-biradical intermediates from undergoing the Norrish Type II cleavage reaction, and pioneering unprecedented 1,6-HAT reactions initiated by excited triplet-state alkenes. We demonstrate the synthetic utility and compatibility of this method across various functional groups, validated through scope evaluation, large-scale synthesis, and derivatization. Our findings are supported by control experiments, deuterium labeling, kinetic studies, cyclic voltammetry, Stern-Volmer experiments, and density functional theory (DFT) calculations.

A comparative study of clinicopathological and imaging features of HBV-negative and HBV-positive intrahepatic cholangiocarcinoma patients with different pathologic differentiation degrees.

Hepatitis B is a risk factor for the development of intrahepatic cholangiocarcinoma. The prognosis of HBV-related ICC remains to be further investigated. To investigate the clinical, pathological and imaging features of intrahepatic cholangiocarcinoma of hepatitis B virus-positive and -negative patients. Data from January 31, 2012 to December 31, 2019 of 138 patients were retrospectively analyzed. The patients were divided into hepatitis B virus-positive group (group A[n = 66]) and virus-negative group (group B[n = 72]), and the patients were divided into groups according to pathological differentiation degree and tumor size. The differences in clinical, imaging characteristics and the progression-free survival between groups were analyzed. There were significant differences in gender, age, HBc antibody, CA125 and AFP, tumor distribution site, maximum diameter, plain scan density, inferior hepatic angle, peritumoral bile duct dilatation, vascular encasement invasion, intrahepatic bile duct dilatation and lymphadenopathy between the two groups (P < 0.05); There were statistical differences in signs of vascular encasement invasion between the two groups with well-to-moderately differentiated tumors (P < 0.05); there were statistical differences in tumor density uniformity, signs of vascular encasement invasion and lymphadenopathy between the two groups with poorly differentiated tumors (P < 0.05). Large groups A and B showed differences in tumor density uniformity, vascular encasement invasion, arterial phase, overall reinforcement pattern, peritumoral bile duct stones and biliary dilatation (P < 0.05). There was no statistical difference in postoperative PFS between the two groups (P > 0.05). The clinical and imaging features of ICC of hepatitis B virus-positive and -negative patients are different, and there is little difference in postoperative disease-free survival time.

Nomogram based on clinical and preoperative CT features for predicting the early recurrence of combined hepatocellular-cholangiocarcinoma: a multicenter study.

PURPOSE: To establish and validate a multiparameter prediction model for early recurrence after radical resection in patients diagnosed with combined hepatocellular-cholangiocarcinoma (cHCC-CC). MATERIALS AND METHODS: This study reviewed the clinical characteristics and preoperative CT images of 143 cHCC-CC patients who underwent radical resection from three institutions. A total of 110 patients from institution 1 were randomly divided into training set (n = 78) and testing set (n = 32) in the ratio of 7-3. Univariate and multivariate logistic regression analysis were used to construct a nomogram prediction model in the training set, which was internally and externally validated in the testing set and the validation set (n = 33) from institutions 2 and 3. The area under the curve (AUC) of receiver operating characteristics (ROC), decision curve analysis (DCA), and calibration analysis were used to evaluate the model's performance. RESULTS: The combined model demonstrated superior predictive performance compared to the clinical model, the CT model, the pathological model and the clinic-CT model in predicting the early postoperative recurrence. The nomogram based on the combined model included AST, ALP, tumor size, tumor margin, arterial phase peritumoral enhancement, and MVI (Microvascular invasion). The model had AUCs of 0.89 (95% CI 0.81-0.96), 0.85 (95% CI 0.70-0.99), and 0.86 (95% CI 0.72-1.00) in the training, testing, and validation sets, respectively, indicating high predictive power. DCA showed that the combined model had good clinical value and correction effect. CONCLUSION: A nomogram incorporating clinical characteristics and preoperative CT features can be utilized to effectively predict the early postoperative recurrence in patients with cHCC-CC.

Visible-light-induced dual catalysis for N-α C(sp3)-H amination and alkenylation of N-alkyl benzamides.

The amination and alkenylation of the C(sp3)-H bond at the N-α position of secondary benzamides were both realized in this work by using N-hydroxyphthalimide (NHPI) imidate esters as substrates under a dual catalysis involving a photoredox catalyst and hydrogen atom transfer (HAT) catalyst. The developed methods significantly extended the scope of applications of the N-α position C(sp3)-H bond functionalization with regard to secondary N-alkylamides. More importantly, new reaction models in photoredox catalysis have been established. Based on corresponding experiments and density functional theory (DFT) calculations on the critical reaction steps combined with information reported previously, we proposed a synergistic photo- and organocatalytic reaction process for the C(sp3)-H bond functionalization and also clarified the occurrence of a chain process in the reaction pathway.

Visible-light-induced indole synthesis via intramolecular C-N bond formation: desulfonylative C(sp2)-H functionalization.

Despite significant advances made on the synthesis of indole derivatives through photochemical strategies during the past several years, the requirement of equivalent amounts of oxidants, bases or other additional additives has limited their practical applications in the synthesis of natural products and pharmaceuticals as environment-friendly processes. Herein, we report LED visible-light-induced redox neutral desulfonylative C(sp2)-H functionalization for the synthesis of N-substituted indoles with a broad scope through γ-fragmentation under mild conditions in the absence of any additional additive. The reaction mechanism paradigm has been investigated on the basis of deuterium labeling experiments, kinetic analysis, Hammett plotting analysis and DFT calculations.

Selective C(sp2)-H bond functionalization of olefins via visible-light-induced photoredox-quinuclidine dual catalysis.

The site selective C(sp2)-H bond functionalization of olefins has been achieved through a visible-light-induced photoredox-quinuclidine dual catalysis upon merging the quinuclidinium radical cation addition to alkene strategy and the distal heteroaryl ipso-migration strategy. This synthetic protocol features a simple operation with readily available starting materials in good step-economy to access alkenylheteroaromatic products in moderate to good yields under mild conditions. A plausible cascade catalytic reaction mechanism is also proposed.