RUTHENIUM CATALYZED OXIDATION OF CYANOHYDRINS TO ACYL CYANIDES USEFUL REAGENTS FOR SELECTIVE N-BENZOYLATION OF AMINOALCOHOLS
Ruthenium catalyzed oxidation of cyanohydrins with tert-butyl hydroperoxide gives the corresponding acyl cyanides in good to excellent yields.Acyl cyanides thus obtained are useful reagents for selective N-benzoylation of aminoalcohols.
A combination of low-valent ruthenium complexes and peroxides such as t-BuOOH and peracids serves as efficient catalytic systems for the oxidation of aromatic and aliphatic hydroxy compounds. The utility of these methods was demonstrated by the synthesis of acyl cyanides which are versatile synthetic intermediates. The principle of the catalytic oxidations with peracids lead to the novel and efficient method for aerobic oxidation of alcohols in the presence of aldehydes. This reaction is of importance in synthetic and large scale industrial processes and from environmental points of view. The present principle will provide new chemistry of oxidative transformations of various industrially important functional materials.
Murahashi,Naota
p. 203 - 213
(2007/10/03)
Ruthenium-catalyzed oxidations for selective syntheses of ketones and acyl cyanides. Selective acylation of amino compounds with acyl cyanides
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 cynides 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 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.
Murahashi,Naota
p. 433 - 440
(2007/10/02)
Palladium-Catalyzed Decarbonylation of Acyl Cyanides
The palladium-catalyzed decarbonylation of aromatic and heteroaromatic acyl cyanides 1 gives the corresponding nitriles 2 in excellent yields.Alkylacyl cyanides can be converted into the corresponding alkenes via decarbonylation followed by β-elimination of hydrogen cyanide.Because of easy preparation of acyl cyanides by the oxidation of cyanohydrins, the present decarbonylation reaction provides an efficient method for the preparation of nitriles from aldehydes under mild and neutral conditions.The catalytic decarbonylation involves the following processes; oxidative addition of acyl cyanides 1 to Pd(PPh3)4 to give acylpalladium complexes 13, acyl-aryl rearrangement, reductive elimination.When an acyl cyanide has a β-hydrogen, the intermediate cyanoalkylcarbonylpalladium (15) undergoes β-elimination to give alkenes.