5.6- Dihydro-l,4,2-dioxazine

CyclischeHydroximsaureester,z.B. 5,6-Dihydro-l,4,2-dioxazine,werdendurchAlkylierung von Hydroxamsauren mit 1,2-Dibrom-ethanen in Gegenwart von Kaliumcarbo-nat95 bzw. aus N-Hydroxy-phthalimiden mit Chlormethyl-oxiran liber die Zwischenstufe des N-(2,3-Epoxy-propyloxy)-phthalimids hergestellt96 z. B. ... 

Acylnitroso compounds are best recognized for their ability to participate as dependable lit components of Diels-Alder reactions with dienes, and these observations have found substantial application in the total synthesis of natural products (Chapter 3). However, Mackay and coworkers have detailed the isolation of 5,6-dihydro-l,4,2-dioxazine 9a (10%) from the reaction of acylnitroso 7a with cyclopentadiene [Eq. (39)] ... 

Although this product may arise from the [3,3]-sigmatropic rearrangement of the oxazine 8a, the acylnitroso 7b provided 5,6-dihydro-l,4,2-dioxazine 9b in excellent yield without the apparent intermediacy of the oxazine 8b. These observations suggest the potentially useful 4ir participation of acylnitroso compounds in Diels-Alder reactions. 

The aryl ether structure of fluoxastrobin (72 2005, HEC Bayer CropScience) [159] combines a methoximino 5,6-dihydro-l,4,2-dioxazin-2-yl toxophore with an optimally adjusted side-chain bearing a 6-(2-chlorophenoxy)-5-fluoro-pyrimidin-4-yl-oxy moiety as an essentia] element. 

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