Reduction reactions amides

Reactions of the carboxyl group include salt and acid chloride formation, esterification, pyrolysis, reduction, and amide, nitrile, and amine formation. Salt formation occurs when the carboxyUc acid reacts with an alkaline substance (22)... 

Conversion of Amides into Amines Reduction Like other carboxylic acid derivatives, amides can be reduced by LiAlH.4. The product of the reduction, however, is an amine rather than an alcohol. The net effect of an amide reduction reaction is thus the conversion of the amide carbonyl group into a methylene group (C=0 —> CTbV This kind of reaction is specific for amides and does not occur with other carboxylic acid derivatives. 

Several syntheses of thienobenzazepines have been reported in the literature however, they generally require the use of reagents and/or reaction conditions which present challenges on a preparative scale. In this manuscript we describe a new and efficient synthesis of the thieno[2,3-c]benzazepine tricycle that involves a key selective reduction-intramolecular amidation cyclization process and enables large-scale preparation of these important compounds. 

It would be interesting to examine thulium diiodide in one-electron reduction reactions. On the basis of the work by Evans and Allen (2000), Tml2 has the potential to be an effective replacement for Sml2, when the latter is too weak as a reductant, when subambient reaction temperatures are desirable, etc. Perhaps, Tml2 activity in THF can be controlled by the addition of hexamethylphosphotri-amide in the same manner as it regulates power and reactivity of SmBr2 (Knettle and Flowers 2001). 

Reduction of amides may yield aldehydes, alcohols or amines. Which of these three classes is formed depends on the structure of the amide, on the reducing agent, and to a certain extent on reaction conditions. 

A number of organic species, including amides, oximes, and nitriles, undergo reductive amination, a variety of reduction reactions that produce cimines. In general, these processes involve imines, R=N-R, or related species. Reduction processes include hydrogenation using Raney nickel as the catalyst (for nitriles), the reaction with sodium/EtOH (for oximes), and the use of lithium aluminum hydride, LiAlH (for amides or nitriles). Figure 13-16 illustrates the preparation of amphetamine by reductive amination. 

Amides require vigorous reaction conditions for reduction by LiAlH4 so that little selectivity can be achieved with this reagent. Diborane, however, permits the reduction of amides in the presence of ester and nitro groups. 

Hydrazotc acid, HN,. ply.. = 4.72, and most of its covalent compounds (including its heavy metal salts) are explosive. It is formed (1) in 90% yield by reaction of sodium amide with nitrous oxide, (2) by reaction of hydraztntum ion with nitrous acid, (3) by oxidation of hydrazimum salts, (4) by reactio n of hydt azinium hydrate with nitrogen trichloride tin benzene solution). Hvdrazoic acid forms metal azides with the corresponding hydroxides and carbonates. It reacts with HC1 to give ammonium chlonde and nitrogen, with H2SO4 to form hydrazinium acid solfate, with benzene to form aniline, and it enters into a number of oxidation-reduction reactions. 

The reduction of amides of fluorocarboxylic acids with the tetrahydroaluminate appears generally hazardous at all stages. During reduction of /V-ethylheptafluor-obutyramide in ether, violent and prolonged gas evolution caused a fire. Towards the end of reduction of trifluoroacetamide in ether, solid separated and stopped the stirrer. Attempts to restart the stirrer by hand caused a violent explosion [1]. During decomposition by water of the reaction complex formed by interaction... 

Liquid injection molding, for silicone rubbers, 3, 674—675 Liquid ligands, in metal vapor synthesis, 1, 229 Liquid-phase catalysis, supported, for green olefin hydroformylation, 12, 855 Lithiacarbaboranes, preparation, 3, 114 Lithiation, arene chromium tricarbonyls, 5, 236 Lithium aluminum amides, reactions, 3, 282 Lithium aluminum hydride, for alcohol reductions, 3, 279 Lithium borohydride, in hydroborations, 9, 158 Lithium gallium hydride, in reduction reactions, 9, 738 Lithium indium hydride, in carbonyl reductions, 9, 713—714... 

During model studies directed towards the synthesis of the Mycalamides, Hoffmann and co-workers 41 discovered a reduction reaction which accompanied the deprotection of an /V-SEM derivative [Scheme 8.152]. Treatment of 152 1 with TT1AF in DMPU at 45 returned the a-hydroxy amide 152 2 as a 3 1 mixture of diastereoisomers. The authors speculate that the reduction reaction was caused by a reagent of the type N-CH2-0 or F-CH2-0 derived from cleavage of the SEM group. The reduction was a welcome and useful surprise since the nascent hydroxyl group is present in the natural product. 

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