N-Alkyl groups

The general rule has been formulated (P) that the less substituted enamine is formed from unsymmetrical ketones such as the 2-alkylcyclohexanones. In enamine 21 the R, group and the N-alkyl groups would interfere with one another if overlap is to be maintained between the nitrogen unshared electrons and the double bond. There would be less repulsion if the isomeric enamine (22) were formed. 2-Phenylcyclohexanone and pyrrolidine with p-toluenesulfonic acid as catalyst in refluxing benzene gave enamine... 

The acid-catalyzed reaction of acetophenone with acyclic secondary amines results in the formation of the expected enamine and a rearrangement product. The latter product arises from the transfer of one of the amino N-alkyl groups to the cnamine s carbon to produce a ketimine (53a). 

A kinetic study of the mercuric acetate oxidation of l-alkyl-3,5-dimethyl-piperidines (81) and 3-alkyl-3-azabicyclo[3.3.1]nonanes (82) was made to evaluate the effect of the N-alkyl group on the rate of oxidation and to contrast these two ring systems (70). The maximum factor in the piperidine... 

The second structural type found for organometallic cobalt porphyrins contains an organic fragment bridged between the cobalt and one pyrrolic nitrogen. Cobalt complexes of N-alkyl- or N-arylporphyrins arc well established (but will not be specifically addressed here). The bridged complexes are derivatives of these where the N-alkyl group also forms a cr-bond to cobalt. They are also related to the axially... 

Combined treatment of atrazine with ozone and H2O2 resulted in retention of the triazine ring, and oxidative dealkylation with or without replacement of the 2-chloro group by hydroxyl (Nelieu et al. 2000). Reaction with ozone and hydroxyl radicals formed the analogous products with the additional formation of the acetamido group from one of the N-alkylated groups (Acero et al. 2000). 

Mcl-PHAs are also classified according to the type of substituent in the alkyl in the side chains so that poly(HAMCL)s containing unsubstituted n-alkyl groups are identified as medium-chain-length poly(3-hydroxy-n-alkanoate) [poly (nHAMCL)]. Both poly(nHAMCL) and PHAs containing unusual groups are described in Sect. 3. 

Triisopropylsilyloxyfurans were effective nucleophiles for the vinylogous Mannich addition to iminium ions that were formed by Rh2(cap)4-catalyzed oxidation of N-alkyl groups by THYDRO <06JA5648>. A stereoselective addition of 2-trimethylsilyloxyfurans to aryl aldehydes-derived aldimines employing a chiral phosphine/Ag complex as catalyst was developed <06AG(I)7230>. The prototypical example is shown below. 

Ester saponifaction was a favoured reaction for this type of study, because the hydrophobicity of the acyl moiety could easily be controlled by increasing the length of an n-alkyl group, and saponification of p-nitrophenyl n-alkanoates could be followed with very dilute substrate. Substrate concentration is an important factor, because provided that it is kept low it is reasonable to assume that the micelle structure is relatively unperturbed. 

Table 1 PAEs with sulfur-containing heteroaromatic rings (C H2 +i is n-alkyl group)... 

Fischer s base (1.6 R = H) with saUcylaldehyde (1.7). The same route can be used with an indolinium compound bearing different N-alkyl groups (1.6 R = alkyl) and ring substituents synthesised as shown in Figure 1.2 by alkylation of a 2-methylin-dole to produce (1.8 R = alkyl). Substituted saUcylaldehydes and also 2-hydroxy-naphthaldehydes can also be used to give other analogues. 

Our aim was to synthesize phosphoric acid triesters XXV and XXVI by the reaction of chloromethyl methylnitrosamine with the corresponding silver salts. Workup allowed the isolation of crystalline substances which were shown to be triesters XXVII and XXVIII. By variation of the N-alkyl group in the nitrosamine from methyl to ethyl, the corresponding phosphoric ethyl ester were obtained. Thus it seems clear that the N-alkyl group was transferred to the oxygen of phosphorus... 

Figure 10.5 Effect of N-alkyl group variation of monoaza crown ethers on extraction efficiency of [C4CjIm][Tf2N] containing N-alkyl aza-18-crown-6 (0.1 M). (Reproduced from the American Chemical Society from Luo, H. M., Dai, S., Bonnesen, R V., Anal. Chem., 76, 2773-2779, 2004. With permission.)...

X-ray analysis of an optically active oxaziridine substituted at nitrogen with the 1-phenylethyl group of known configuration led to the absolute configuration (+)-(2R,3R)-2-(S-1 -phenylethyl)-3-(p-bromophenyl)oxaziridine of the dextrorotatory compound as expected, C-aryl and N-alkyl groups were trans to each other (79MI50800). 

If, however, hydrogen is present in the a-position of the (V-alkyl substituent, 2-alkyl-oxaziridines are easily decomposed by alkali. Base attack on this H atom effects 1,2-elimination at the C—N bond. From (86) and aldimine (87) forms, and a mixture of ammonia and two carbonyl compounds is finally obtained, one of them containing the carbon atom of the original oxaziridine ring, the other originating from the N-alkyl group (57JA5739). 

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