A Scrutiny on the Reductive Amination of Carbonyl Compounds Catalyzed by Homogeneous Rh(I) Diphosphane Complexes
摘要:
The reductive amination of a series of aldehydes with secondary amines and H-2 in the presence of a homogeneous Rh-diphosphane catalyst was studied in order to establish a general mechanism of this reaction and to identify conditions for the improvement of the amine/alcohol ratio in the product. Several possible intermediates as constituents of changing equilibria like half-aminals. N,O-acetals and aminals were observed in the reaction mixture by means of H-1 NMR spectroscopy. In individual trials, these compounds could be successfully hydrogenated under the conditions applied for reductive amination (50 bar H-2 pressure, MeOH). Some evidence is accumulated that half-aminals and N,O-acetals might be key intermediates of the reductive amination. Moreover, it was found that the formation of the undesired product alcohol is likely based on the reduction of the starting carbonyl compound. However, due to numerous equilibria consisting of several intermediates, general conclusions are hard to be drawn. Proof will be given that, in several cases, the efficiency of the reductive amination of aliphatic aldehydes can be significantly improved by prehydrogenation of the cationic [Rh(dppb)(COD)](+) complex.
[EN] CHEMICAL PROCESSES AND COMPOUNDS DERIVED THEREFROM<br/>[FR] PROCÉDÉS CHIMIQUES ET COMPOSÉS DÉRIVÉS DE CEUX-CI
申请人:UNIV MONASH
公开号:WO2006012683A1
公开(公告)日:2006-02-09
The present invention relates to N-substituted anilines and derivatives thereof and in particular to chemical processes for the preparation of N-substituted anilines and derivatives thereof.
本发明涉及N-取代苯胺及其衍生物,特别是用于制备N-取代苯胺及其衍生物的化学过程。
Rediscovering aminal chemistry: copper(<scp>ii</scp>) catalysed formation under mild conditions
作者:Juliana G. Pereira、João P. M. António、Ricardo Mendonça、Rafael F. A. Gomes、Carlos A. M. Afonso
DOI:10.1039/d0gc01977a
日期:——
aldehyde lithiation. Nevertheless, the existing methodologies for their formation typically employ harsh conditions limiting their usefulness. In this work, we present an efficient and mild methodology for the preparation of aminals from aromatic aldehydes, including furanic platforms. These mildconditions allowed ease of access to a plethora of aminals and as such we set out to explore previously unaccessible
SYNTHESIS OF SOME NEW SUBSTITUTED FLAVANONES AND RELATED 4-CHROMANONES BY A NOVEL SYNTHETIC METHOD
作者:Mihail Lucian Birsa
DOI:10.1081/scc-120001517
日期:2002.1.1
ABSTRACT A new heterocyclocondensation between substituted N,N,-dialkyldithiocarbamates and benzaldehyde aminals is described. The mild reaction condition, easily accessible reactants, offers a new useful synthesis of flavanones or 4-chromanones.
The unprecedented direct detection of the freeradical intermediate 7 in the reduction of Schiff bases 2 to the corresponding amines by formic acid using the EPR technique is reported. Monitoring the same reaction by NMR, line broadenings and signal shifts are observed, while the further evolution to products is triggered off by heating. No product formation or line broadening/shifts of the imine derivatives
Atom-efficient transition-metal-free arylation of <i>N</i>,<i>O</i>-acetals using diarylzinc reagents through Zn/Zn cooperativity
作者:Andryj M. Borys、Jose M. Gil-Negrete、Eva Hevia
DOI:10.1039/d1cc04137a
日期:——
Exploiting the cooperative action of Lewis acid Zn(C6F5)2 with diarylzinc reagents, the efficient arylation of N,O-acetals to access diarylmethylamines is reported. Reactions take place under mild reaction conditions without the need for transtion-metal catalysis. Mechanisticinvestigations have revealed that Zn(C6F5)2 not only acts as a Lewis acid activator, but also enables the regeneration of nucleophilic
利用路易斯酸 Zn(C 6 F 5 ) 2与二芳基锌试剂的协同作用,报道了N , O -缩醛的有效芳基化以获得二芳基甲胺。反应在温和的反应条件下进行,不需要过渡金属催化。机理研究表明,Zn(C 6 F 5 ) 2不仅可以作为路易斯酸活化剂,而且可以使亲核 ZnAr 2物质再生,允许使用限制为 50 mol%。