Some chiralcatalysts have been tested in the reaction of ethyl 2-bromopropionate with potassium phthalimide and in the borohydride reduction of phenyl t-butyl ketone under phase-transfer conditions. The mechanism of the N-alkylation reaction and the influence of the molecular structure of the catalysts on stereoselectivity are analysed.
Nonsymmetrical Azocarbonamide Carboxylates as Effective Mitsunobu Reagents
作者:Daniel P. Furkert、Benjamin Breitenbach、Ludovic Juen、Ina Sroka、Mathilde Pantin、Margaret A. Brimble
DOI:10.1002/ejoc.201403152
日期:2014.12
Mitsunobu reagents possessing both dialkyl amide and ester substituents was developed. These new reagents were readily prepared in a single pot from inexpensive, commercially available materials by using a scalable and environmentally friendly procedure. They were shown to exhibit activity parallel to that of diethyl azodicarboxylate/diisopropyl azodicarboxylate in a wide variety of Mitsunobu reactions
N-Substituted phthalimides can be obtained in very good yields, under essentially neutral conditions, by mixing or heating an alkyl (oraryl) azide, triphenylphosphine, and phthalicanhydride in benzene or toluene, in the presence of a catalytic amount of tetrabutylannionium cyanide. Application of the reaction into the domain of carbohydrates is promising.
Clean inversion of secondary mesylates and tosylates is effected by CsF in DMF. A variety of oxygen-, sulfur-, nitrogen-, and carbon-nucleophiles are employable. The reaction conditions have been optimized. The use of CsF in DMF is crucial and the reaction proceeds on the surface of solid CsF. It is suggested that hydrogen bonding between CsF and an active hydrogen of nucleophiles is responsible for the smooth reaction. Cesium carbonate fails to give rise to high specificity of inversion indicative of superiority of CsF. (C) 1997 Elsevier Science Ltd.