Beckmann and cyclization reactions of δ-oxo-α,β-unsaturated ketoximes obtained from pyrylium salts and hydroxylamine. formation of 2-aryl(or alkyl)amino-4,6-disubstituted pyrylium salts
作者:Cornelia Uncuţa、Adriana Tudose、Miron Teodor Căproiu、Marieta Plăveţi、Rita Kakou-Yao
DOI:10.1016/s0040-4020(99)00958-8
日期:1999.12
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
2,4,6-三取代的吡啶鎓盐1与羟胺的反应给出了区域和立体选择性的1,3,5-三取代的2-顺-戊烯-1,5-二酮1-肟4。在环化时,获得分别源自肟4的安硫炔立体异构体的3,5,5-三取代的2-异恶唑啉6和2,4,6-三取代的吡啶1-氧化物5。酮基酮肟4与亚硫酰氯的贝克曼反应出乎意料地得到2-芳基(或烷基)氨基-4,6-二取代的吡啶鎓盐7,是涉及羰基氧作为终止剂的重排/环化的第一个例子。提供了用于(晶体学数据Ž) - ñ -吨丁基-3,6,6-三甲基-2- heptenecarboxamide 13B。