- Pt(IV)-catalyzed generation and [4+2]-cycloaddition reactions of o-quinone methides
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Novel intermolecular and intramolecular generations of ortho-quinone methides and their formal [4+2]-cycloaddition reactions with olefins catalyzed by PtCl4 and AuCl3 under mild conditions have been developed. Good to excellent yields (up to 99%) and diastereoselectivity (up to >99:1) of the chromans were obtained. PtCl4 was found to be effective and compatible with various functional groups present in the substrates. A mechanism accounting for its catalytic cycle is proposed and discussed.
- Radomkit, Suttipol,Sarnpitak, Pakornwit,Tummatorn, Jumreang,Batsomboon, Paratchata,Ruchirawat, Somsak,Ploypradith, Poonsakdi
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p. 3904 - 3914
(2011/06/22)
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- Design, synthesis and biological evaluation of novel riccardiphenol analogs
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A novel, facile, high yield, and less cumbersome synthesis of riccardiphenol analogs is described. The synthesized compounds were characterized and assessed for its in vitro activity in a panel of human cancer cell lines of differing origin: HuCCT-1, BxPC3, Panc-1, Mia-Paca, A431, Hep2, and HN006. HuCCT-1 was derived from an intrahepatic cholangiocarcinoma; BxPC3, Mia-Paca, and Panc-1 were derived from pancreatic cancers; A431 was derived from a vulvar epithelial carcinoma; and Hep2 and HN006 were derived from squamous cell carcinomas of the head and neck. The cytotoxicity of a newly developed riccardiphenol analog against human cancer cell lines was assessed. The cancer cells exhibited varying sensitivities to the compound, with IC50 values from 30 to 50 μM. This susceptibility was particularly interesting in the case of lines such as Hep2 and BxPC3 that are resistant to classic cytotoxic drugs as well as some targeted agents. These results demonstrate that the novel riccardiphenol analog has effective action against human-derived cancer cell in vitro.
- Kumar, Srinivas K.,Amador, Maria,Hidalgo, Manuel,Bhat, Sujata V.,Khan, Saeed R.
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p. 2873 - 2880
(2007/10/03)
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- Total synthesis and absolute configuration of riccardiphenols A and B, isolated from the Liverwort Riccardia crassa
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The title compounds were synthesized as optically active forms using chiral Michael addition of the imine, prepared from 2-methylcyclohexanone and (S)-(-)-phenylethylamine, to methyl propiolate. The etherification of the intermediate triol was accomplished by TsOH-catalyzed cyclization. The absolute configurations of the natural products, riccardiphenols A and B, were established as 1 and 2, respectively.
- Tori,Hamaguchi,Sagawa,Sono,Asakawa
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p. 5362 - 5370
(2007/10/03)
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