- Use of Hypervalent Iodine in the Synthesis of Isomeric Dihydrooxazoles
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[Figure not available: see fulltext.] A convenient synthesis of 2- and/or 3-oxazolines has been developed depending on the structure and stereochemistry of the starting amino alcohol. PhI(OAc)2 acted as oxidant on the intermediate imine, as sup
- Carlucci, Claudia,Tota, Arianna,Colella, Marco,Ronamazzi, Giuseppe,Clarkson, Guy J.,Luisi, Renzo,Degennaro, Leonardo
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p. 428 - 436
(2018/06/11)
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- Stereoselective synthesis of β-lactams by condensation of titanium enolates of 2-pyridyl thioesters with imines bearing a chiral auxiliary
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Several amines have been tested as chiral auxiliaries in the stereoselective synthesis of β-lactams by condensation of the titanium enolates of 2-pyridyl thioesters with chiral imines. The amines were selected among the following classes of compounds: ben
- Annunziata, Rita,Benaglia, Maurizio,Cinquini, Mauro,Cozzi, Franco,Raimondi, Laura
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p. 9471 - 9486
(2007/10/02)
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- Synthetic Versatility of N(Silylmethyl)imines: Water-Induced Generation of N-Protonated Azomethine Ylides of Nonstabilized Type and Fluoride-Induced Generation of 2-Azallyl Anions
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N-(Silylmethyl)imines generate N-protonated azomethine ylides of nonstabilized type when treated with water in HMPA, which undergo stereospecific and regioselective cycloadditions with electron-poor olefins affording N-unsubstituted pyrrolidines.On the other hand, fluoride-induced desilylation of the imines leads to 2-azallyl anions which are found to be synthetic equivalents of aminomethyl anion in the Michael additions with electron-poor olefins and nucleophilic additions with carbonyl compounds.
- Tsuge, Otohiko,Kanemasa, Shuji,Hatada, Akira,Matsuda, Koyo
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p. 2537 - 2546
(2007/10/02)
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- SYNTHETIC APPLICATIONS OF CHROMIUM(VI) REAGENTS IN COMBINATION WITH CHLOROTRIMETHYLSILANE
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The synthetic utility of chromium(VI) reagents together with chlorotrimethylsilane, as new oxidizing systems, is described.Pyridinium dichromate (PDC) in combination with chlorotrimethylsilane oxidizes tert-butyldimethylsilyl ethers in good to excellent yields.Trimethylsilyl chlorochromate, a new chromium(VI) reagent, also was found efficient for this oxidative-deprotection method.These reagents were applied to the oxidation of some N-(2-phenyl-2-hydroxyethyl)azetidin-2-ones as well as N-(2-phenyl-2-trialkylsiloxy)azetidin-2-ones into their corresponding carbonyl compounds, key intermediates for N-unsubstituted β-lactams.Oxidation of hydroquinones and protected trialkylsilyl hydroquinones was also described.Protection of hydroquinones by means of the tert-butyldimethylsilyl group was achieved by using the readily available tert-butyldimethylchlorosilane (TBDMCS) and 1,8-diazabicycloundec-7-ene (DBU) as base, which avoids the use of sophisticated and (or) sensitive reagents.
- Cossio, Fernando P.,Aizpurua, Jesus M.,Palomo, Claudio
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p. 225 - 231
(2007/10/02)
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