Results 151 to 160 of about 453,943 (222)

Asymmetric [3+3] Cycloaddition of N‐Vinyl Oxindole Nitrones with 2‐Indolylmethanols to Prepare Spirooxindole[1,2]oxazines

Advanced Synthesis & Catalysis
We describe a chiral phosphoric acid (CPA) catalyzed asymmetric [3+3] cycloaddition of N‐viny oxindole nitrones with 2‐indolylmethanols to prepare various spirooxindole[1,2]oxazines in 43‐93% yields and 88:12‐97:3 enantiomeric ratios.
Ning Zou, Yu‐Zheng Wu, Xin‐Yi Zhong, Cui Wei, Li-Min Liao, Dong‐Liang Mo, Wen-Jun Zhou   +6 more
semanticscholar   +1 more source

Iodine(III)-Mediated Keto-oximation of O-Alkynyl Hydroxylamines: A Route to 3-Acyl Isoxazolines and 1,2-Oxazines.

Organic Letters
An intramolecular iodine(III)-mediated keto-oximation of O-alkynyl hydroxylamines offers rapid and straightforward access to 3-acyl Δ2-isoxazolines and 1,2-oxazines.
Santosh J. Gharpure, Kaushik C Pansuriya, Juhi Pal, Showkat A Hajam, Sanyog Kumari   +4 more
semanticscholar   +1 more source

Sc(OTf)3‐catalyzed tandem (3+3)‐annulation/lactonization of cyclopropanes with salicylaldehyde nitrones to access polycyclic 1,2‐oxazines

Journal of Heterocyclic Chemistry
A Sc(OTf)3‐catalyzed tandem (3 + 3)‐annulation/lactonization of donor‐acceptor cyclopropane 1,1‐dieters with salicylaldehyde nitrones has been reported, affording a wide range of tetrahydrochromeno[4,3‐c][1,2]oxazin‐5(1H)‐ones in moderate yields with ...
Zhipin Liu, J. Pang, Lijie Che, Liping Pang, Chunfang Gan, Jianguo Cui, Yanmin Huang   +6 more
semanticscholar   +1 more source

Regio-, Enantio-Controlled Cascade Oxa-Michael Addition of Hydroxyl Amine: Synthesis of Dihydro-1,2-Oxazines.

Journal of Organic Chemistry
Herein, we disclose a cinchona-alkaloid-based squaramide-catalyzed intermolecular oxa-Michael cascade addition cyclization of N-protected hydroxyl amine to formyl-tethered Michael acceptors toward the synthesis of enantioenriched 1,2-oxazine scaffolds ...
Chandan Kamilya, P. Ghorai
semanticscholar   +1 more source

Nitrogen inversion in 3,6‐dihydro‐1,2‐oxazines

Organic Magnetic Resonance, 1980
AbstractThe nitrogen inversion barriers of nine 3,6‐dihydro‐1,2‐oxazines are discussed. Polar solvents were found to increase the nitrogen inversion barriers which, in turn, decrease with increasing size of the N‐substituent.
Henryk Labaziewicz, Frank G. Riddell
openaire   +1 more source

Synthesis of tetrahydro-1,2-oxazin-3-one

Bulletin of the Academy of Sciences of the USSR Division of Chemical Science, 1962
1. Tetrahydro-l,2-oxazin-3-one was synthesized. 2. A new reaction-the decyclization of butyrolactone under the action of acetone oxime with formation of 4-(aminooxy)butyric acid-was discovered.
R. M. Khomutov, M. Ya. Karpeiskii, E. S. Severin   +2 more
openaire   +1 more source

ChemInform Abstract: Reductive Transformations of 6H‐1,2‐Oxazines with Hydride Reagents: Formation of Aziridines and 3‐Hydroxyalkylated 1,2‐Oxazines.

ChemInform, 1994
AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
R. ZIMMER, K. HOMANN, H.‐U. REISSIG
openaire   +1 more source

MsOH‐Mediated Cascade Cyclization of O ‐Homopropargyl Hydroxylamines with Aldehydes to Access 4‐Arylidene‐1,2‐Oxazines

Annalen der Pharmacie
Brønsted acid‐mediated synthesis of 4‐arylidene oxazines from O ‐homopropargyl hydroxylamines is developed. A series of control experiments have been carried out, revealing that the formation of 4‐arylidene oxazines proceeds through an alkyne–oximium
Santosh J. Gharpure, Kaushik C Pansuriya, Juhi Pal   +2 more
semanticscholar   +1 more source

Synthesis of 6H-1,2-oxazin-6-ones (microreview)

Chemistry of Heterocyclic Compounds, 2020
The microreview is devoted to the methods of synthesis of 6H-1,2-oxazin-6-ones published after 1999 and covers both universal and specific methods for the preparation of this class of compounds.
Alexey V. Nizovtsev, Mikhail S. Baranov
openaire   +1 more source

ChemInform Abstract: 3,6‐Dihydro‐2H‐1,2‐oxazines (Microreview)

ChemInform, 2016
AbstractReview: [21 refs.
Greta Utecht, Marcin Jasinski
openaire   +1 more source