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Since the first reports on the photoreactions of 1-phenyl-2-(pentamethyldisilanyl)ethyne 1 and phenylpentamethyldisilane 2 by Ishikawa et al., the intermolecular photolysis of these compounds and their derivatives has been extensively investigated. It is well known that the photolysis of 1-phenyl-2-(pentamethyldisilanyl)ethyne afforded silacyclopropene 3-10 and 1-sila-1,2-propadiene 11-13 intermediate and the photoreaction of phenylpentamethyldisilane gave silatriene 14-20 intermediate. However, relatively little is known about the intramolecular photoreactions of ortho-substituted 1-phenyl-2-(pentamethyldisilanyl)ethynes and ortho-substituted phenylpentamethyldisilanes.Recently, we have found that the photolysis of orthosubstituted 1-phenyl-2-(pentamethyldisilanyl)ethynes 21 and ortho-substituted phenylpenta methyldisilanes 22,23 afforded the novel intramolecular photoproducts via silacyclopropene, 1-sila-1,2-propadiene, and silatriene intermediates.Very recently, we have found that the photoreaction of (2-hydroxymethylphenyl)pentamethyldisilane 24 and (2-hydroxyethoxyphenyl)pentamethyldisilane 25 afforded the novel intramolecular photoproducts via silatriene intermediates.In connection with our ongoing studies for the utility of silacyclopropenes, 1-sila-1,2-propadiene, and silatriene as reaction intermediates in organic synthesis of silicon-containing heterocyclic compounds, we were now interested in the synthesis of silicon-containing large ring compounds via the photolysis of ortho-substituted phenylpentamethyldisilanes. And, we have investigated the photoreactions of (2-hydroxypropoxyphenyl)pentamethyldisilane 2, since novel photoproducts from the intramolecular reaction of orthosubstituted group with the silatriene intermediate are expected and we would like to report the detailed photochemical study of 2.The starting material 2 was prepared by the reaction of (2-hydroxyphenyl)pentamethyldisilane 25 (1) with 3-chloro-1-propanol in the presence of sodium hydroxide and tetra-nbutyl ammonium iodide using microwave reactor, Micro-SYNTH in water as a solvent as shown in Scheme 1.To investigate whether or not the hydroxypropoxy group as ortho-substituent in 2 reacts intramolecularly with silatriene moiety in the reaction intermediate 3 formed in the photoexcited state of 2, the photoreaction of 2 in benzene was studied.Photolysis of 2 in deaerated benzene with 254 nm UV light gave a novel photoproduct 6 (32% yield) along with some decomposition products of unknown structure as shown in Scheme 2, when 95% of 2 was photolyzed but the expected intramolecular photoproduct was not obtained. The formation of a novel photoproduct 6 can best be explained in terms of the initial formation of silatriene intermediate 3 arising from1,3-migration of trimethylsilyl radical, which is formed via the homolytic cleavage of silicon-silicon bond of pentamethyldisilanyl group in the photoexcited state of 2 to the C6 position of benzene ring as shown in Scheme 2. The intramolecular reaction to form a oxirane ring in this silatriene ...

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Lung cancer can be divided into non-small cell lung cancer (NSCLC) and small cell lung cancer, and the incidence and mortality rate are continuously increasing. In many cases, lung cancer cannot be completely treated with surgery, so chemotherapy is used in parallel; however, the treatment often fails due to drug resistance. Therefore, it is necessary to develop a new therapeutic agent with a new target. The expression of sphingosine kinase promotes cancer cell growth and survival and induces resistance to chemotherapeutic agents. Sphingosine-1-phosphate (S1P), produced by sphingosine kinase (SK), has been shown to regulate cancer cell death and proliferation. PF-543, currently known as an SK inhibitor, has been reported to demonstrate low anticancer activity in several cancers. Therefore, in this study, a derivative of PF-543 capable of increasing anticancer activity was synthesized and its efficacy was evaluated by using an NSCLC cell line and xenograft animal model. Based on the cytotoxic activity of the synthesized compound on lung cancer cells, the piperidine forms (Compounds 2 and 4) were observed to exhibit superior anticancer activity than the pyrrolidine forms of the head group (Compounds 1 and 3). Compounds 2 and 4 showed inhibitory effects on SK1 and SK2 activity, and S1P produced by SK was reduced by both compounds. Compounds 2 and 4 demonstrated an increase in the cytotoxicity in the NSCLC cells through increased apoptosis. As a result of using an SK1 and SK2 siRNA model to determine whether the cytotoxic effects of Compounds 2 and 4 were due to SK1 and SK2 inhibition, it was found that the cytotoxic effect of the derivative was SK1 and SK2 dependent. The metabolic stability of Compounds 2 and 4 was superior compared to PF-543, and the xenograft experiment was performed using Compound 4, which had more excellent MS. Compound 4 demonstrated the inhibition of tumor formation. The results of this experiment suggest that the bulky tail structure of PF-543 derivatives is effective for mediating anticancer activity, and the results are expected to be applied to the treatment of NSCLC.

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It is well known that the photoreactions of aryldisilanes show four reaction patterns 1 since the first report on the photolysis of phenylpentamethyldisilane and (p-tolyl)pentamethyldisilane by Ishikawa et al.2 in 1975 : (path a) formation of a silene compound via elimination of a trimethylsilane 3 , (path b) formation of a silene compound arising from 1,3-shift of trimethylsilyl radical, which is formed via homolytic cleavage of silicon-silicon bond [4][5][6][7][8][9] , (path c) formation of a trimethylsilyl compound via elimination of a silylene 10,11 , (path d) formation of a direct solvolysis compound via elimination of a trimethylalkoxysilane or pentamethylalkoxydisilane. 12,13Silenes having the C=Si moiety are regarded as highly interesting intermediates. Consequently the synthesis and reactions of silenes as useful intermediates have been extensively investigated.14,15 The intermolecular reactions between highly unstable silenes and the compounds containing functional groups such as OH [16][17][18][19][20][21][22] , C=O 23-26, and C=C 27-31 bonds resulted in the formation of the addition products.In connections with the photolysis of aryldisilanes, we recently disclosed the intramolecular reactions between the silene intermediates resulted from the photoreactions of ortho-substituted aryldisilanes and ortho-substituents to give the novel silicon-containing heterocyclic compounds such as the photoinduced intramolecular reactions of (2-substitutedphenyl)pentamethyldisilanes 32 , (2-alkoxymethylphenyl)pentamethyldisilanes 33 , 2-(pentamethyldisilanyloxy)phenylpentamethyldisilane 34 and (2-hydroxyethoxyphenyl)pentamethyldisilane. 35 We have also investigated the synthesis of siliconcontaining heterocyclic compounds through the intramolecular reactions of silacyclopropene or 1-silaallene moiety with ortho-substituents in ortho-substituted-phenylethynylpentamethyldisilanes 36. As a part of our continuous studies utilizing the silenes as reaction intermediates for the synthesis of silicon-containing heterocyclic compounds, we investigated the photoreactions of (2-acetoxyphenyl)pentamethyldisilane which has the acetoxy group as ortho substituent to phenylpentamethyldisilane because it was expected that the novel photoproducts could be formed from the intramolecular reaction of ortho-substituted acetoxy group with the silene intermediate. In this note, we would like to report the detailed photochemical study of (2-acetoxyphenyl)pentamethyldisilane.The starting (2-acetoxyphenyl)pentamethyldisilane 2 was prepared from the reaction of (2-hydroxyphenyl)pentamethyldisilane 1 35 with acetyl chloride using triethylamine as base in tetrahydrofuran at room temperature (Scheme 1).In order to investigate a possibility that the C=O bond as ortho substituent in 2 reacts intramolecularly with a silene, the photolysis of 2 was performed.Irradiation of 2 in deaerated benzene with 254nm UV light afforded two photo-Fries rearrangement products 4 (18% yield) and 5 (10% yield) along with some decomposition products of unknown structu...

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Aryl pyridjl ethers were prepared from phcnols and active halopyridines under essentially neutral condition via fluoride ion assisted reaction. Owing to the increasing interest of heteroanalogs of diphenyl ethers like Fluazifop-butyl 1 in agricultural applications as herbicide', the development of a facile synthetic methodology of forming ether linkage is certainly warranted. CF, *O-@ 0-CH -C 9 -0-C&C&CH,CH, Fluazifop-butyl -1 The ether linkage between pyridine ring and phenyl moiety of Flazifop-Butyl 1 can be formed via several routes. However, we were particularly interested in the preparation of aryl pyridyl ethers like -1 under essentially neutral condition.