Trialkylamine N-oxide

Since the PK reaction with electron-defident alkynes was also problematic, even when stoichiometric Co2(CO)g was employed, promoters such as trialkylamine N-oxide were required for the reaction to proceed [14]. Alternatively, W(CO)5-THF may be employed semi-catalytically for this class of substrates [9cj. The rhodium catalyst [RhCl(CO)2]2, has shown great versatility for electron-deficient alkynes (Scheme 11.4) the reaction times are much shorter (1-3 h) than those of the usual examples (Tab. 11.3). This rhodium-catalyzed PK reaction may be extended to the synthesis of 6,5-fused ring analogs, as exemplified in the synthesis of bicyclo[4.3.0]nonenone 2o from the 1,7-enyne lo (Eq.4) [13 bj. 

Deoxygenation of amine oxides. Trialkylamine N-oxides and dialkylarylam-ine N-oxides are converted to the tertiary amines on reaction with this anhydride in CH2C12 at 25°.1... 

From IR studies it has been concluded that the N—O stretch of trialkylamine N-oxides is practically insensitive to coordination, unlike their aromatic counterparts, but that the predominantly M—O stretching frequencies are higher than in the aromatic cases. This has been attributed, in part, to the lack of 7c-character in the N—O bond which makes these the more effective ligands. 

Oxone adsorbed on silica gel or alumina is a very effective oxidant for the selective oxidation of primary and secondary amines to hydroxylamines without overoxidation. These reactions can even be accomplished under solvent-free conditions and with very short reaction times with heating or microwave irradiation (eq 53). Pyridine and trialkylamines were also readily oxidized to their N-oxides. It is suggested that the hydroxylamines are protected from overoxidation because of their strong adsorption to the silica gel or alumina surface. 

Transalkylation of Tertiary Amine A-Oxides. N- t-Butyldimethylsilyloxy)-A-methylpiperidinium triflate is quantitatively formed from the reaction of A-methylpiperidine A-oxide (eq 13). The resulting amine salts derived from various trialkylamine A-oxides undergo transalkylation by treatment with Methyllithium in THF at 0 °C followed by alkyl halides and Tetra-n-butylammonium Fluoride in a sealed tube at 110 °C for 10 h, to afford trisubstituted amines (eq 14). ... 

Numerous cationic azo dyes are prepared by the action of /V-hydroxymcthyl-chloroacetamide on azo dyes in sulfuric acid medium, followed by displacement of the reactive chloro substituent by pyridine or trialkylamine. Of special significance for dyeing paper are dyes that are prepared by coupling of diazotized 2-(4 -aminophenyl)-5-methylbenzothiazole to acetoacetaiylides, pyrazolones, naphthols [143], or barbituric acid derivatives [144], followed by reaction with N-hydroxymethylchloro-acetamide and pyridine. The azo dye obtained by oxidative dimerization of 2-(4 -aminophenyl)-5-methylbenzothiazole may also be subjected to this conversion [145], Dye 51 colors paper yellow. 

Trialkylamines can be effectively used as transfer agents in phase transfer peroxomolybdate oxidations of thioethers to sulphones. Use of tri-n-butylamine in this way brings a number of advantages over traditional quaternary ammonium ions avoidance of tars and easy separation of products from catalyst and auxiliaries. 

Trialkylamines in aqueous solution undergo hydroxide ion catalyzed oxidative dealkylation, affording secondary nitroxyl radicals R R N-O beside olefins and carbonyl compounds [57]. An... 

In the first step, the nucleophilic addition reactions need to be controlled under inert gas atmosphere because both triethylphosphine and tri(n-butyl)phosphine are quite pyrophoric and easy to react with oxygen in air to form trialkylphosphine oxides. However, the nucleophilic addition reactions are relatively fast when compared to those of the corresponding trialkylamines [15]. Another important point is a selection of halides. The rates of the reaction with alkyl bromide are much... 

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