N, V-Dimethylaniline

The rate constants for proton transfer as a function of substituent and solvent are given in Table 2.3 [43]. All experiments involved the 355-nm irradiation of various benzophenones in the presence of 0.4 M N, /V-dimethylaniline. 

Table 23 The secondary a-deuterium and incoming nucleophile nitrogen KIEs found for the Sn2 reactions between p-substituted N,/V-dimethylanilines and methyl iodide in ethanol at 25°C.a...

Baeyer-Villiger reaction of 57 with H3PO5 gives the phenol 59. However, the peracetic acid or trifluoroperacetic acid gives the carboxylic acid 58 (equation 93)258. Oxidation of N,V-dimethylaniline in aqueous CH3CN at 30 °C affords the V-oxide in 82% yield256. 

Nucleophilic substitution occurs in the 2, 4. and 6 positions of pyridine under relatively mild conditions. As an example, amination of pyridine with sodium amide in N, /V-dimethylaniline at I80°C gives 2-aminopyridine in good yield. 

Table 2 Addition-Oxidation with Anisole, N,/V-Dimethylaniline and [(Fluorobenzene)Cr(CO)3] Complexes...

In summary, although the BH model predicts an inverted region for the kinetics of proton in the nonadiabatic regime, the BH model is only in qualitative accord with the data derived from the proton transfer within the benzophenone-N, /V-dimethylaniline contact radical ion pairs. The failure of the model lies in its ID nature as it does not take into account the degrees of freedom for the vibrations associated with the proton-transfer mode. By incorporating these vibrations into the BH model, the LH model provides an excellent account of the parameters serving to control the kinetics of nonadiabatic proton transfer. A more rigorous test for the LH model will come when the kinetic deuterium isotope effects for benzophenone-iV, /V-di methylaniline contact radical ions are examined as well as the temperature dependence of these processes are measured. 

Just how good nitrogen is in donating electrons into the jc system is shown by comparing the relative rates for the bromination of benzene, methoxybenzene (anisole), and N /V-dimethylaniline. 

The effect of the ortfto-methyl group in N,)V-dimethylanilines on 13C chemical shift has also been found useful for evaluating the angle and barrier to rotation of the NMe2... 

Photoreduction of benzophenones and acetophenones by amines has been studied in detail. A mechanism has been derived for the reaction of benzophenone with N,)V-dimethylaniline that involves a triplet exciplex in the formation of the radical ion pair, as indicated in Scheme 49. 

The intermediate in the Gabriel-Posner synthesis of quinazolin-2(lH)-one (fusion of o-aminobenzaldehyde with excess of urea), was found to be o-ureidobenzylidene urea (19), which then cyclized on heating, or in the presence of acid, with elimination of urea. The intermediate reacted with aniline, iV-methylaniline, and N,V-dimethylaniline to form 4-p-aminophenyl, 4-p-methylaminophenyl, and 4-p-dimethylaminophenyl quinazolin-2(lH)-ones in an unusual manner. Several quinazolin-2(li/)-ones were prepared by converting o-acylanilines into o-ureidophenyl ketones followed by cycli-zation in acetic acid medium for long periods at 55°C. A novel modification of this cyclization involved a Curtius or Hofmann reaction on 2 -benzoyl-oxanilic acid chlorides (20 = Cl) or amides (20 = NH2), respectively. 

A -Dialkylarylamines react under classical conditions at C-4 if that position is unsubstituted. For example, N V-dimethylaniline reacts with formaldehyde and dimethylamine to afford 4-N X-dimethyl-amino-A V-dimethylbenzylamine in 82% yield (equation 20).37 Under acidic conditions fragmentation of the initial product can occur, leading to the formation of diarylmethanes. In the reaction of A V-dimethy-laniline with formaldehyde and pyrrolidine the best yield of the Mannich base (44%) is obtained in the presence of 1.5 mol equiv. of acetic acid with 4.0 mol equiv. the yield is only 7%.38 The reaction of N-methylenemorpholinium chloride with 4-N -morpholinylmethyl-N,lV-dimethylaniline results in the introduction of a second /V-morpholinylmethyl residue at the 2-position, but with other iminium chlorides quaternary salts are formed by reaction with the nitrogen of the 4-dialkylaminomethyl group.39 There is also a brief report of the use of the mixed N V-dialkylmethyleneiminium salt, N-r-butyl-N-methyl-methyleneiminium perchlorate, with N V-dimethylaniline.40... 

Our preliminary studies show that the catalyst system can tolerate at least some functionalities on the arene thus, while substrates containing unprotected -OH or COoH groups are hydrogenated only to a small degree or not at all, aryl-ethers (anisole), -esters (methyl benzoate), -ketones (acetophenone, benzophenone), and N,]V-dimethylaniline are all hydrogenated. In general, no products corresponding to states of intermediate reduction (cyclohexenes or cyclohexadienes) are detected. 

Several reports describe the formation of dimethylamino-biphenyls. The photochemical reaction of p-dimethylaminotoluidine in the presence of an electron acceptor such as tetracyanoethene results in (258), while phenylation of N/V-dimethylaniline N-oxide (259) with benzene in the presence of trifluoromethanesulphonic acid gives mainly 4(-JVN-dimethylamino)-biphenyl (260) together with small amounts of the 2-isomer. 

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