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Carboxy‐ and Cyano‐Hydroxylation of Alkenes. Synthesis of 3‐Hydroxy‐4‐amino Acids and Butyrolactones via the Isoxazoline Route
Author(s) -
Halling Karen,
Thomsen Ib,
Torssell Kurt B. G.
Publication year - 1989
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.198919890255
Subject(s) - chemistry , dehydrohalogenation , catalysis , hydroxylation , organic chemistry , potassium carbonate , acetic acid , reagent , cycloaddition , medicinal chemistry , hydrogenolysis , sodium hypochlorite , lactone , hydrogen , enzyme
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.