- A chiral cobalt(II) complex catalyzed asymmetric formal [3+2] cycloaddition for the synthesis of 1,2,4-triazolines
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A highly efficient catalytic asymmetric formal [3+2] cycloaddition reaction of 5-alkoxyoxazoles with azodicarboxylate compounds has been realized by a chiral N,N′-dioxide/Co(BF4)2·6H2O complex. A series of poly-substituted 1,2,4-triazolines compounds were obtained in moderate to excellent yields (70-99%) with excellent enantioselectivities (82-98% ee).
- Ma, Baiwei,Luo, Weiwei,Lin, Lili,Liu, Xiaohua,Feng, Xiaoming
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p. 4077 - 4079
(2017/04/13)
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- Copper-Catalyzed Aerobic Oxidative [2 + 3] Cyclization/Aromatization Cascade Reaction: Atom-Economical Access to Tetrasubstituted 4,5-Biscarbonyl Imidazoles
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An atom-economical method for accessing tetrasubstituted 4,5-biscarbonylimidazoles by reaction between glycine derivatives and 5-alkoxyoxazoles is reported. The method, which involves a copper-catalyzed aerobic oxidative [2 + 3] cyclization/aromatization
- Xie, Jialin,Huang, Yuanqiong,Song, Hongjian,Liu, Yuxiu,Wang, Qingmin
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p. 6056 - 6059
(2017/11/27)
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- Titanium-catalyzed stereoselective synthesis of spirooxindole oxazolines
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A regio-and stereoselective cyclization between isatins and 5-methoxyoxazoles has been developed using catalytic titanium (IV) chloride (10 or 20 mol %) to afford spiro[3,3'-oxindoleoxazolines] in excellent yield (up to 99%) and diastereoselectivity (dr >
- Badillo, Joseph J.,Arevalo, Gary E.,Fettinger, James C.,Franz, Annaliese K.
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p. 418 - 421
(2011/04/15)
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- Evolution of the total syntheses of ustiloxin natural products and their analogues
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Ustiloxins A-F are antimitotic heterodetic cyclopeptides containing a 13-membered cyclic core structure with a synthetically challenging chiral tertiary alkyl-aryl ether linkage. The first total synthesis of ustiloxin D was achieved in 31 linear steps using an SNAr reaction. An NOE study of this synthetic product showed that ustiloxin D existed as a single atropisomer. Subsequently, highly concise and convergent syntheses of ustiloxins D and F were developed by utilizing a newly discovered ethynyl aziridine ring-opening reaction in a longest linear sequence of 15 steps. The approach was further optimized to achieve a better macrolactamization strategy. Ustiloxins D, F, and eight analogues (14-MeO-ustiloxin D, four analogues with different amino acid residues at the C-6 position, and three (9R,10S)-epi-ustiloxin analogues) were prepared via the second-generation route. Evaluation of these compounds as inhibitors of tubulin polymerization demonstrated that variation at the C-6 position is tolerated to a certain extent. In contrast, the S configuration of the C-9 methylamino group and a free phenolic hydroxyl group are essential for inhibition of tubulin polymerization.
- Li, Pixu,Evans, Cory D.,Wu, Yongzhong,Cao, Bin,Hamel, Ernest,Joullie, Madeleine M.
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p. 2351 - 2364
(2008/09/20)
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- A novel preparation of 2-aryl-5-methoxyoxazoles
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2-Aryl-5-methoxyoxazoles can be synthesized by oxidation of Schiff's bases with (diacetoxyiodo) benzene in good yields under mild conditions.
- Xia
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p. 382 - 383
(2007/10/03)
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