Amines, N-arylation

N-Alkyl- IV/ld, 284 2-[l -(9- Anthryl)-2,2,2-trifluor-ethoxy]- E21a, 266 (R-COOH 4- Amine) N-Aryl-diazo- E14b, 1158 (aus 1,2,3-Triazolen)... 

Limitations Most of the catalysts currently require imines derived from aromatic amines. N aryl amines are thus easily made (as in the synthesis of SCH48461) but if primary amines are the target, the N aryl group has to be removed (as in the synthesis of colchinol). 

Keywords Aryl iodides, aliphatic amines, CuBr, racemic-1,1 -binaphthyl-2,2 -diol (rac-BINOL), K3PO4, N,N-Dimethyl formamide (DMF), room temperature, coupling reaction, amination, N-arylation of aliphatic amines... 

During their studies of the reaction of free sugars with amines, N-aryl-o-fructosylamines were synthesized by Sorokin [14], Kuhn and Birkofer [94], as well as Barry and Honeymoon [95] but, in contrast to N-arylaldosylamines, these compounds could not be induced, under the conditions applied, to rearrange into the desired a-aminocarbonyl compounds. 

R—N=N Aryl diazonium 10ns are formed by treatment of primary aromatic amines with nitrous acid They are ex tremely useful in the preparation of aryl halides phenols and aryl cyanides... 

In addition to iV-azo coupling to form triazenes, aromatic amines (R = aryl in Scheme 13-1) also undergo C-azo coupling because they are ambidentate nucleophiles. The competition between N- and C-coupling will be discussed in Section 13.3. 

Primary aromatic amines (e.g., aniline) and secondary aliphatic-aromatic amines (e. g., 7V-methylaniline) usually form triazenes in coupling reactions with benzenedi-azonium salts. If the nucleophilicity of the aryl residue is increased by addition of substituents or fused rings, as in 3-methylaniline and 1- and 2-naphthylamine, aminoazo formation takes place (C-coupling). However, the possibility has also been noted that in aminoazo formation the initial attack of the diazonium ion may still be at the amine N-atom, but the aN-complex might rearrange too rapidly to allow its identification (Beranek and Vecera, 1970). 

Bei N-Aryl-carbamidsaureestern werden dagegen die N-Hydroxymethyl-amine erhalten z.B.1 ... 

Independently, Caddick et al. reported microwave-assisted amination of aryl chlorides using a palladium-N-heterocyclic carbene complex as the catalyst (Scheme 99) [lOlj. Initial experiments in a domestic microwave oven (reflux conditions) revealed that the solvent is crucial for the reaction. The Pd source also proved very important, since Pd(OAc)2 at high power in DMF gave extensive catalyst decomposition and using it at medium and low power gave no reaction at all. Pd(dba)2/imidazohum salt (1 mol% catalyst loading) in DME with the addition of some DMF was found to be suitable. Oil bath experiments indicated that only thermal effects are governing the amination reactions. 

The reaction of amines with aryl halides requires a catalyst in most cases to initiate the reaction. There are several approaches that result in N-aryl amines. Treatment of cyclohexylamine with p-MeC6H4B(OH)2 and Cu(OAc)2 gave the N-aryl amide in 63% yield. Aryl halides react with amines in the presence of palladium... 

Grubbs reported the synthesis of several N, N -aryl substituted imidazolinium salts 35 from chiral Ar,AT -aryl diamines obtained by palladium-catalyzed amination of the appropriate aryl bromide with (li, 2i )-diaminocyclohexane... 

Overman LE, Owen CE, Pavan MM, Richards CJ (2003) Catalytic asymmetric rearrangement of allylic N-aryl trifluoroacetimidates. A useful method for transforming prochiral allylic alcohols to chiral allylic amines. Org Lett 5 1809-1812... 

The N,N-diethylamide of salicylic acid is a useful ligand in conjunction with Cul and permits amination of aryl bromides by primary alkylamines.151... 

Watanabe reports a new method for the direct conversion of o-choroacetaldehyde N,N-disubstituted hydrazones into 1-aminoindole derivatives 93 by palladium-catalyzed intramolecular ring closure of 92 in the presence of P Bu3 or the bisferrocenyl ligand 94 <00AG(E)2501>. When X = Cl, this cyclizative process can be coupled with other Pd-catalyzed processes with nucleophilic reagents (e.g., amines, azoles, aryl boronic acids) so as to furnish indole derivatives with substituents on the carbocyclic ring. 

Oxidative attack on a carbon-hydrogen bond of an alkyl group a to a nitrogen atom is not restricted to saturated aliphatic amines. In fact X in an X-N-CH- structural subunit can be virtually any common atomic grouping that can be found in stable organic molecules. For example, w-carbon hydrogens of Aralkyl-substituted aromatic cyclic amines (119), aryl amines (120), amides (121), amidines (122), A-nitrosodialkylamines (123), etc. are all subject to oxidative attack, carbinolamine formation, and in most cases release of an aldehyde or ketone depending on the substitution pattern (1° or 2°)... 

Only a few more recent examples of the numerous studies on N-arylations with aryllead triacetates will be discussed here. For earlier publications in this field, the interested reader is referred to the pioneering arylations of aliphatic and aromatic amines by Barton s group, 8 as well as the comprehensive review article by Elliott and... 

As mentioned above, iridium complexes are also active in the formation of amines via the hydrosilylation/protodesUylation of imines. In the presence of 2 equiv. of HSiEts, the cationic complex [lr bis(pyrazol-l-yl)methane (CO)2][BPh4] (C4) catalyzes the reduction of various imines, including N-alkyl and N-aryl imines and both aldimines and ketimmes. Excellent conversions directly to the amine products were achieved rapidly at room temperature in a methanol solution (Scheme 14.7) [53]. 

The double N-arylation of primary amines or ammonia equivalents 592 with 2,2 -biphenylylene ditriflate (591) under Buchwald-Hartwig N-arylation conditions gave the unsymmetrically multi-substituted carbazoles 593. Among the various... 

VAPOL-derived phosphoric acid 11 was shown to catalyze the amidation of Boc-protected N-aryl imines with sulfonamide, phthaUmide, and maleimide nucleophiles to furnish the corresponding chiral aminals in excellent yields and ee s (Scheme 5.29) [52, 53]. This represents the first general catalytic and asymmetric... 

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