Synthese und thermischer Zerfall von O‐Alkyl‐N‐vinylhydroxylamin‐Derivaten

Abstract

Die 0x0-iminiumsalze I l a -e und 13a -e werden durch Oximierung der w-Chlorketone 9a -e iiber die cyclischen Oximether 10a -e bzw. die cyclischen Imin-oxide 12a -e und deren anschlienende Alkylierung mit ,,Meerweinsalr" hergestellt. Die Deprotonierungsreaktionen von 11 a -e sowie 13a-e fiihren uber die regioselektiv hergesiellten Zwischenprodukte 14a-e bzw. 17a-e zu den a,p-ungesattigten lminen 15a -e und den cyclischen lminen 18a -e. Synthesis and Thermolysis of 0-Alkyl-N-vinylhydroxylamine DerivativesOxoiminium salts l l a -e and 13a-e have been prepared from the o-chloroketones 9 a -e by oximation via the cyclic oxime ethers 10a-e and the cyclic imine oxides 12a-e, followed by alkylation with ,,Meerwein salt". The deprotonation reaction of 11 a -e and 13a -e yields, uiu the regioselectively prepared intermediates 14a -e and 17a -e, the a$-unsaturated imines 15a -e and the cyclic imines 18a-e, respectively.In Fortfuhrung unserer Untersuchungen uber 0x0-iminiumsalze') bemiihten wir uns urn die Synthese sowie die chemischen Anwendungsm6glichkeiten der bisher nur wenig untersuchten N-Vinyl-O-alkylhydroxylamine2'.

Rearrangement of N-Oxyenamines and Related Reactions

“…Other examples of retro-ene reactions of N -alkoxy-enamines have also been reported. ,,, For example, the derivatives 435 , formed by deprotonation of the salts 434 , were observed by low-temperature NMR analysis (Scheme , eq 1) . The N -alkoxyenamines 437 are the intermediates of the base-promoted decomposition of 2-alkylpyridinium salts 436 (Scheme , eq 2) …”

“…Thus, the 3-cyano-substituted products 408 (R′ = 3-CN) undergo cycloreversion during work up . Some alkyl-substituted 2 H -oxazines 408 were observed using NMR techniques at −65 °C, but they underwent cycloreversion on warming up to −20 °C . The N -siloxyderivatives 416 (Chart ) seemed to decompose already at negative temperatures. , The O-anions 417 also cycloreverse to the corresponding enoximes .…”

Photochemical Rearrangement of Oxaziridines and Nitrones in the Hexahydroindole Series: A Convenient Synthetic Route to 1-Azabicyclo[5.2.0]nonan-2-ones as Novel RGD Mimetics

“…Na 2 WO 4 ·H 2 O gave the highest yield of 38% 22b. This method is superior to another reported synthesis of nitrone 10 (yield ca. 12%).…”

Chemistry of Six-Membered Cyclic Oxime Ethers. Application in the Synthesis of Bioactive Compounds

“…The initial functionalized oximes 44 can be obtained from the corresponding ketones 45 and hydroxylamine (route 1, Scheme ) or by the nitrosation of chlorides 46 containing an activated methylene group (route 2, Scheme ). In some procedures, the cyclization 44 → 1 occurs simultaneously upon the preparation of the starting oximes. ,− …”