化学
脱卤化氢
催化作用
羟基化
有机化学
碳酸钾
醋酸
试剂
环加成
药物化学
氢解
次氯酸钠
内酯
氢
酶
作者
Karen Halling,Ib Thomsen,Kurt Torssell
标识
DOI:10.1002/jlac.198919890255
摘要
Abstract Dichloro‐ and dibromoformaldoximes are useful 1,3‐dipolar cycloaddition reagents. They are conveniently preparated in situ, in high yields by dihalogenation of glyoxalic acid aldoxime with N ‐bromo‐ and N ‐chlorosuccinimide or tert ‐butyl hypochlorite. Dehydrohalogenation with potassium hydrogen carbonate in the presence of alkenes gives 3‐halo‐isoxazolines in a one‐pot reaction. Reduction with iron pentacarbonyl gives β‐hydroxynitriles. Methoxylation and catalytic reduction give β‐hydroxy esters. Allyl alcohols and allylamines are transformed with halonitrile oxides into butyrolactones ( DL ‐angelica lactone) and DL ‐3‐hydroxy‐4‐amino acids (carnitine, 4‐amino‐3‐hydroxybutyric acid), respectively. The lactonization is best effected by heating the γ‐silyloxy ester in acetic acid with potassium hydrogen sulfate as catalyst. A synthesis of N ‐Boc‐dihydromuscimol is described.
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