The synthesis and some reactions of N-hydroxycarbamates
作者:E. Boyland、R. Nery
DOI:10.1039/j39660000346
日期:——
chloroformate, gave N-hydroxy-N-phenylurethane. Hydroxylamine hydrochloride and ethyl chloroformate yielded a product which changed into hydroxyurethane. Alkyl N-hydroxycarbamates and hydroxyurea gave O-xanthydryl derivatives. The N-hydroxycarbamates with aqueous dipotassium tetracyanonickelate(II) formed dipotassium tricyanonitrosylnickelate(II). No evidence of a Lossen-type rearrangement during the acid
羟胺和氯甲酸烷基酯在碱性介质中反应,以形成ñ - , - NO -二- ,和NNO -三烷氧羰基羟胺,依次。N-甲基羟胺类似地得到N-和NO-二烷氧基羰基-N-甲基-羟胺,O-甲基羟胺产生N-和NN-二烷氧基羰基-O-甲基羟胺。N-苯基羟胺与1当量的氯甲酸乙酯反应,得到N-羟基-N-苯基氨基甲酸酯。盐酸羟胺和氯甲酸乙酯产生产物,其变为羟基氨基甲酸酯。N-羟基氨基甲酸酯烷基和羟基脲得到O-黄羟基衍生物。所述Ñ -hydroxycarbamates用含水四氰二钾(II)而形成二钾tricyanonitrosylnickelate(II)。在这些羟氨基衍生物的酸和碱水解过程中,没有证据表明发生了洛森型重排。讨论了可能的水解机理。
Hydroxamic Acids as Chemoselective (<i>ortho</i>
-Amino)arylation Reagents via Sigmatropic Rearrangement
The use of readily available hydroxamic acids as reagents for the chemoselective (ortho‐amino)arylation of amides is described. This reaction proceeds under metal‐free, mild conditions, displays a very broad scope, and constitutes a direct approach for the metal‐free attachment of aniline residues to carbonyl derivatives.
An efficient 1-pot procedure for the Zn-mediated redn. of nitro arenes in the presence of chloroformates leading to the corresponding N,O-bisprotected hydroxylamine is described. Reactions proceed smoothly under ambient conditions in THF-water mixts. in good to excellent yield (34-81%). Solvolysis of the bisprotected hydroxylamines with NaOMe at room temp. provides access to synthetically versatile
Enantioselective Synthesis of 2-Isoxazolines by a One-Flask Conjugate Addition/Oxime-Transfer Process
作者:Antti Pohjakallio、Petri M. Pihko
DOI:10.1002/chem.200802684
日期:2009.4.14
Enantioselective isoxazoline synthesis: A combination of 1) a catalytic enantioselectiveconjugateaddition of oximes to α,β‐unsaturated aldehydes and 2) an acid‐catalyzed intramolecular oxime‐transfer reaction lead to the first asymmetric synthesis of 3‐unsubstituted 2‐isoxazolines (see scheme).
Synthesis of α-Amino Acids by Umpolung of Weinreb Amide Enolates
作者:Sebastian Hirner、Donata K. Kirchner、Peter Somfai
DOI:10.1002/ejoc.200800683
日期:2008.11
An efficient and diastereoselective synthesis of alpha-amino acids from readily available starting materials has been developed. The key feature of this reaction is an umpolung of a glycine-derived ...