作者:Evelina Colacino、Pierrick Nun、Francesco Maria Colacino、Jean Martinez、Frédéric Lamaty
DOI:10.1016/j.tet.2008.03.091
日期:2008.6
13C MAS nuclear magnetic resonance experiments. We have also studied the temperature profile during the reaction. A comparative study with the corresponding solvent-free microwave activated reaction showed the superiority of the ball-milling method; 31 examples are described, including the synthesis of the anti-aging agent C-phenyl-N-tert-butyl nitrone (PBN) and one of its analogues C-2-pyridyl-N-tert-butylnitrone
Electronic effects in 1,3-dipolar cycloaddition reactions of N-alkyl and N-benzyl nitrones with dipolarophiles
作者:Andrei Bădoiu、E. Peter Kündig
DOI:10.1039/c1ob06144e
日期:——
1,3-Dipolar cycloadditions afforded fast access to isoxazolidines bearing N-alkyl or N-benzyl substituents. The electronic properties of the substituents in the nitrones define the activity of the dipoles and modulate diastereoselectivity in the non-catalyzed reactions. Using a chiral one-point binding ruthenium Lewis acid catalyst, products were obtained in good yields and with excellent regio-, diastereo-
Rh2(esp)2-Catalyzed Redox/Cycloaddition Cascade of Diazoacetoacetate Enones with N-Methyl Nitrones: Diastereoselective Synthesis of β-Lactams with Two Adjacent Chiral Centers
作者:Xichen Xu、Yingjun Zhao、Rujie Xu、Zhengqing Xu
DOI:10.1055/s-0040-1719883
日期:2022.5
employing Rh2(esp)2 as the catalyst, a reaction cascade operates by reducing an N-methyl nitrone to the corresponding N-methyl imine in the presence of a first molecule of the diazoacetoacetate enone. A second molecule of the diazoacetoacetate enone sensing a change in the reaction medium undergoes a Wolff rearrangement to afford a vinyl ketene. This vinyl ketene then reacts with the in situ generated
Chromium and Tungsten Pentacarbonyl Groups as Reactivity and Selectivity Auxiliaries in [3 + 2] Cycloaddition of Alkynyl Fischer Carbene Complexes with N-Alkyl Nitrones
作者:Kin Shing Chan、Ming Lok Yeung、Wai-kin Chan、Ru-Ji Wang、Thomas C. W. Mak
DOI:10.1021/jo00111a036
日期:1995.3
Alkynyl Fischer carbene complexes were found to undergo chemoselective, regioselective, and rate-enhanced 1,3-dipolar cycloaddition with nitrones to give 2,3-dihydroisoxazole carbene complexes in excellent yields. These alkynyl complexes can serve as synthons for substituted propiolate esters since the metal pentacarbonyl group of the cycloadducts can be easily oxidatively removed with DMSO. The tungsten carbene complex 4b reacted with 3 different series of N-alkyl nitrones: N-tert-butyl 2a-f, N-methyl 1a-h and N-benzyl 3 to give cycloadducts 6a-f, 7a-h, and 8-9, respectively, while the chromium carbene complex 4a reacted only with N-tert-butyl nitrones 2a-g to give isolable cycloadducts 5a-g. The structure of N-methyl cycloadduct 7d has been established by a single-crystal X-ray analysis. The reactivity of N-alkyl nitrones toward carbene complexes was in the order: N-Me > N-Bn > N-(t)Bu. In addition, our results showed that the rate of cycloaddition reaction increased as the electron donating ability of para-substituent in N-tert-butyl nitrone 2a-f increased.
Cyclic carbamates and isoxazolidines as IIb/IIIa antagonists
申请人:DuPont Pharmaceuticals Company
公开号:US06004955A1
公开(公告)日:1999-12-21
##STR1## This invention relates generally to cyclic carbamates and hydroxylamines which are useful as antagonists of the platelet glycoprotein IIb/IIIa fibrinogen receptor complex, to pharmaceutical compositions containing such compounds, processes for preparing such compounds, and to methods of using these compounds for the inhibition of platelet aggregation, as thrombolytics, and/or for the treatment of thromboembolic disorders.