Under microwave irradiation 3Å molecular sieves promote the oxidation of secondary (linear and cyclic) and benzylic alcohols to the corresponding carbonyl compounds by t-butylhydroperoxide. Under the same conditions, α,β-unsaturated alcohols are converted into α,β-epoxyalcohols in regio- and diastereoselective way. Both oxidative processes can be performed under solvent-free conditions; however, epoxidation
From allylic alcohols to saturated carbonyls using Fe(CO)5 as catalyst: scope and limitation studies and preparation of two perfume components
作者:Hassan Cherkaoui、Mohammed Soufiaoui、René Grée
DOI:10.1016/s0040-4020(01)00114-4
日期:2001.3
The direct conversion of allylicalcohols to saturated carbonyls, using Fe(CO)5 as a catalyst, offers good synthetic potential. Mono-, di- and even trisubstituted alkenes bearing various alkyl, aryl and electronwithdrawing groups on the allylic system give good to excellent yields of rearranged products. Limitations occur mainly with polyunsaturated derivatives. This reaction was applied to a short
Ruthenium-Catalyzed Oxidations for Selective Syntheses of Ketones and Acyl Cyanides. Selective Acylation of Amino Compounds with Acyl Cyanides
作者:Shun-Ichi Murahashi、Takeshi Naota
DOI:10.1055/s-1993-25877
日期:——
Oxidation of alcohols to the corresponding carbonyl compounds with tert-butyl hydroperoxide in the presence of dichlorotris(triphenylphosphine)ruthenium catalyst gives the corresponding carbonyl compounds with high efficiency. This method can be applied to the oxidation of cyanohydrins to give acyl cyanides which are versatile synthetic intermediates. Acylation of amino compounds with acyl cyanides thus obtained proceeds chemoselectively. Thus, the reaction of amino alcohols with acyl cyanides gives N-acylated products exclusively. In the similar N-acylation of polyamines primary amines are selectively acylated in the presence of secondary amines. These reactions are highly useful for the synthesis of spermidine and spermine alkaloids such as spermidine siderophores. Dimeric cyclocoupling reaction of diacyl cyanides such as iso- and terephthaloyl cyanides with polyamines can be performed under the similar reaction conditions to give the corresponding polyazamacrocycles with high efficiency.
racemic compounds. However, it was possible to use asymmetric synthesis for the preparation of opticallyactive aldols. Various mechanistic studies have been performed using, for instance, a deuterated alcohol or a deuterated catalyst. They gave strong support to a mechanism involving first a transition-metal-mediated isomerization of the allylicalcohol into the free enol, followed by the addition of