Carbanion, electrophilic amination

Cannizzaro reaction, 2, 3 Carbanion, electrophilic amination, 72, 1 Carbenes, 13, 2 26, 2 28, 1 Carbene complexes in phenol and quinone synthesis, 70, 2... 

The action of chloroamine and bromoamine on organometallic reagents has been reviewed102 and a comprehensive review of electrophilic aminations of carbanions has appeared103. Alkyl, alkenyl and aryllithium compounds are converted into tertiary amines 84 by reaction with the mesityl compounds 83 (R2 = Me or Et Ar = 2,4, 6-MesCeHj)104. 

This methodology is also an important and potentially valuable method for C—N bond formation using the amination of carbon nucleophiles with electrophilic nitrogen transfer reagents (Scheme 1) Amination of ordinary carbanions and a-carbanion derived from carbonyl compounds and nitriles provides an important method for the synthesis of amines and a-amino carbonyl compounds and nitriles", respectively. For this purpose, a number of electrophilic amination reagents, which are synthetic equivalents of the R2N+ synthon, have been developed and the synthetic potential of electrophilic amination of carbon nucleophiles has been studied in detail . ... 

Substituted hydroxylamines 1-5 (R = R = H) and their A-mono- or A,A-disub-stituted derivatives 1-5 have been used extensively for electrophilic amination of both carbanions and enolates since the first report in 1938 on the use of 0-methylhydroxylamine 1 (R = Me) for conversion of Grignard reagents to primary amines. Oximes 7 (Z = H) have found limited applicability as amination reagents for carbon nucleophiles and then-use was first reported in 1907. Ketone 0-sulfonyloximes 7 (Z = SO2R) have recently been developed. 

This chapter on electrophilic amination using O-substituted hydroxylamines 1-5 and oximes 7 is focused on the various methods that have been reported for the amination of carbon nucleophiles. Synthetic aspects and applications of the methods for C—N bond formation are accompanied by a brief discussion of the reaction mechanisms. The preparation of O-substituted hydroxylamines and oximes has not been considered in detail. This review covers the literature up to August 2007 and is partly based on reviews on the electrophilic amination of carbanions and a-amination of carbonyl compounds. ... 

The only reported example of the use of O-phenylhydroxylamine Ig for electrophilic amination of carbanions is the conversion of phenyhnagnesium bromide into aniline. ... 

There are a few reports on the use of oximes as electrophilic amination reagents. Since 1984, ketone O-sulfonyloxknes have found applicability as amino transfer reagents to car-banions. In the reaction of organometaUic compounds with oximes, carbanions attack the carbonyl carbon of the oxime, giving Af-substituted hydroxylamines as addition products (Scheme 53, path a). However, a number of scattered reports have been also published on the formation of aziridines by a-deprotonation, followed by addition (path b) or formation of azirines by a-deprotonation before addition (path c). Addition of carbanions to azirines also yields aziridines, which are hydrolyzed to a-aminoalcohols. 

In this chapter, C—N couplings, e.g. substitution reactions of carbanions on nitrogen atom of oximes to yield primary amines, have been reviewed. A list of oximes and 0-sulfonyloximes used for electrophilic amination is given in Table 6. These reagents aminate carbanions to A-organylimines as isolable intermediates which are hydrolyzed to primary amines (Scheme 53, path d Scheme 54). Depending on the organometaUic... 

Armstrong et al. studied the electrophilic amination of carbanions with A -carboxamido-oxaziridines <2000TL2247>. A range of 3-aryl-A -carboxamido oxaziridines was evaluated and the 3-(2-cyanophenyl) oxaziridine 108 gave optimum yields of the amination products. A variety of ketone, ester, and amide enolates, as well as sulfone-, phosphonate-, and nitrile-stabilized carbonions underwent the desired amination (Table 6). 

Little work could be found on the electrophilic amination of simple nitrile-stabilized carbanions. The lithium anion of propionitrile reacts normally with an N-substituted oxaziridine (Eq. 141).158 The amination of nitriles with a camphor-derived N-unsubstituted oxaziridine was discussed earlier (Eq. II).151 Aminoma-lononitrile is formed from malononitrile anion and 0-(mesitylenesulfonyl)hydro-xylamine (Eq. 142).463... 

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