C. Uncuţa, A. Tudose, M. Cǎproiu
Dec 24, 1999
Citations
0
Influential Citations
10
Citations
Journal
Tetrahedron
Abstract
The reaction of 2,4,6-trisubstituted pyrylium salts 1 with hydroxylamine gave regio- and stereo-selectively 1,3,5-trisubstituted 2- cis -pentene-1,5-dione 1-oximes 4 . On cyclization, 3,5,5-trisubstituted 2-isoxazolines 6 and 2,4,6-trisubstituted pyridine 1-oxides 5 were obtained, originating in the antilsyn stereoisomers of oxime 4 , respectively. Beckmann reaction of keto-ketoximes 4 with thionyl chloride unexpectedly gave 2-aryl (or alkyl) amino-4,6-di-substituted pyrylium salts 7 , the first example of rearrangement/cyclization involving carbonylic oxygen as terminator. Crystallographic data are provided for ( Z )- N - t -butyl-3,6,6-trimethyl-2-heptenecarboxamide 13b .