ABSTRACT
Direct oxidative C(sp)-H/C(sp3 )-H cross-coupling offers an ideal and environmentally benign protocol for C(sp)-C(sp3 ) bond formations. As such, reactivity and site-selectivity with respect to C(sp3 )-H bond cleavage have remained a persistent challenge. Herein is reported a simple method for iron-catalyzed/silver-mediated tertiary alkylation of terminal alkynes with readily available and versatile 1,3-dicarbonyl compounds. The reaction is suitable for an array of substrates and proceeds in a highly selective manner even employing alkanes containing other tertiary, benzylic, and C(sp3 )-H bonds alpha to heteroatoms. Elaboration of the products enables the synthesis of a series of versatile building blocks. Control experiments implicate the in situ generation of a tertiary carbon-centered radical species.
ABSTRACT
[This corrects the article DOI: 10.3892/ol.2017.6940.].
ABSTRACT
An efficient tertiary alkylation reaction of olefins with 1,3-dicarbonyl compounds was developed by virtue of copper catalyst without the use of expensive ligands or additives. In contrast to alkyl Heck-type reaction, alkyl halide is not required. Notably, by varying the nitrogen and air atmosphere, the reaction selectively produces alkylation and alkylation-oxygenation products, respectively. Initial investigations revealed that an α-carbonyl alkyl radical species might be involved in the process.
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A radical-mediated oxidative cross-coupling of readily accessible α-alkylated styrenes with 1,3-dicarbonyl compounds utilizing a combination of Cu(OAc)2 and air as a catalytic system is described. Rather than requiring α-halocarbonyl compounds, this efficient approach enables direct installation of tertiary functionalized alkyl motifs to olefins with simple carbonyl derivatives. The novel protocol is characterized with high allylic selectivities via a competing ß-H elimination. Both radical-clock and -trapping experiments provided clear-cut evidence for the intermediacy of an α-keto carbon-centered radical.
ABSTRACT
Radiotherapy resistance is an enduring major setback in lung cancer therapy, and is responsible for a large proportion of treatment failures. In previous years, cyclooxygenase-2 (COX-2) has frequently been reported to promote tumor occurrence and development, suggesting a potential role in radiotherapy resistance. To investigate whether COX-2 inhibitors can be applied in radiosensitization, an MTT assay was performed to examine cell viability after X-ray radiation in the presence or absence of the specific COX-2 inhibitor Celecoxib. Cell apoptosis and cell cycle changes were also detected through laser confocal scanning microcopy and flow cytometry. X-ray treatment only caused mild cell death in lung cancer A549 cells. However, combination treatment using celecoxib and X-ray radiation exhibited improved inhibitory effects and significantly suppressed cell proliferation. Therefore, COX-2 inhibitors combined with radiotherapy can counteract radiation-induced high COX-2 expression, demonstrating that celecoxib can function as a radiosensitizer of lung cancer cells. It is therefore reasonable to predict COX-2 inhibitors to be potential clinical radiotherapy synergists.
ABSTRACT
BACKGROUND: Non-small cell lung cancer (NSCLC) is the leading cause of cancer mortality worldwide. Platelet activation may play an important role in pathologic progress in lung cancer. In this study, we aimed to clarify the influence of activated platelets on lung cancer generation and growth, and the relationship among these functional and ultrastructural changes of platelets and the severity of pathogenetic condition in these patients with NSCLC. METHODS: One hundred and thirty-six cases of patients with pathologically confirmed NSCLC were included in this study. Fifty-four healthy people were enrolled as controls. The change of ultra microstructure and activity of blood platelets were observed under the transmission and scanning electron microscope. Simultaneous determination of plasma granule membrane protein 140 (GMP-140) was made. RESULTS: Transmission electron microscopy showed remarkable changes of ultra microstructure of platelets in patients with NSCLC, including swelling, increase of a-granules, vesicles, and glycogenosome. Scanning electron microscopy showed many more surface processes and wrinkles on platelets in patients with NSCLC. The reference plasma levels of GMP-140 of healthy controls were (18.2 +/- 2.7) microg/L. The plasma levels of GMP-140 in patients with NSCLC were (47.8 +/- 12.3) microg/L, which were much higher than those of the controls. There was a medium positive correlation between plasma levels of GMP-140 and amount of a-granules (r = 0.514, P < 0.01) and a high positive correlation between plasma levels of GMP-140 and area of platelet (r = 0.84, P < 0.01) in patients with NSCLC. The Kaplan-Meier survival curve analysis showed significant shift to the left in patients with NSCLC whose a-granules per platelet were 19 or more compared to those 18 or less (Log rank statistic, chi(2) = 17.38, P < 0.01). CONCLUSIONS: There are significant activated changes of ultra microstructure and increased activity of blood platelets in patients with NSCLC. These activated platelets may play an important role in the generation and growth of lung cancer. These changes can be used as a diagnostic index of severity, progression, and prognosis of NSCLC.
