Arylamine hydrochloride

A series of 3-substituted 2-nitrosiminobenzothiazohnes (35a-e) as well as the disub-stituted analog 35f were prepared (Scheme 3.24) [198]. The reaction of an arylamine hydrochloride with potassium thiocyanate gave the corresponding unsymmetrical thiourea [199]. Oxidative cyclizations with bromine provide the iminobenzothia-zolines [191, 200], which on treatment with sodium nitrite in acetic acid afforded the nitrosiminobenzothiazoline (35a-f). The nitrosiminobenzoselenazoline (42) was similarly prepared. 

It has been known for some time that alkyl- or arylamine hydrochlorides... 

Amino-6-arylaminopurines. These interesting purines (2), many of which have useful biological effects, can be prepared directly from guanine (1) by reaction with an arylamine hydrochloride and P205 in the presence of (C2HS),N-HC1 at 200°. ... 

The opportunity to introduce substituents at C-2 of the pyrrolopyrimidine is afforded by the use of 2-(substituted)amino-3-cyanopyrroles. Treatment of acylaminopyrroles (127), most commonly with R3 = Me, with phosphorus pentoxide, an arylamine hydrochloride, and jV,Ar-dimethyl-cyclohexylamine at elevated temperatures, gives the derivatives (128 X = NH) (Equation (42)) <83LA2066,84CS73, 85CS222,85S101,88CS303,90H(3l)367,93AP(326)303>. In some cases the 4-imino derivative has been converted to the 4-oxo derivative (128 X = O) by hydrolysis. 

The results (Table 9) indicate that the Mannich bases deriving from attack on the less substituted C atom arc obtained more frequently, the B attack being preferred only under particularly selected reaction conditions, such as the use of mcthyleneimmonium salts in dilute trifluoroacetic acid solution for very long reaction times " or with ethanolic primary arylamine hydrochlorides.- However, few exceptions to the prevailing behavior have been observed. - - ... 

In general, arylamine hydrochlorides or hydrobromides give better yields than using the free amines. This strategy was used in the synthesis of 6-(arylamino)purin-2-amines 10 starting from guanine. ... 

The short and convenient synthesis of novel naphthopyranoquinolines from naphthopyran chloroaldehydes via the Doebner-Miller synthesis was developed in the laboratory of J.K. Ray. The chloroaldehydes were treated with 2.5 equivalents of a substituted aniline in ethanol in the presence of 2N HCI to afford enaminoimine hydrochlorides in good yield. These hydrochloride salts were exposed to heat at a temperature slightly above their melting point, resulting in ring-closure and elimination of one equivalent of arylamine hydrochloride. 

Amidines 101 can also be generated by treatment of amides 103 with arylamine hydrochlorides in the presence of dehydrating agents, such as P2O5. In this case, attempts to isolate the corresponding amidines failed, but this procedure made it possible to prepare thienopyrimidines 99 (1981CS245, 1988CS195). 

In an extension of this method, the corresponding 9-arylamino derivatives result directly when the ester, cyclohexanone and an arylamine hydrochloride are heated with phosphorus pentoxide and -dimethylcyclohei lamine. Under these conditions, anthranilamide affords the unsubstituted 9-aminoacridine, presumably yia the nitrile (N.S. Girgis and E.B. Pedersen, Synthesis, 1985. 547). 

Another interesting application of iminium chlorides in organic synthesis involves their use as catalysts in the conversion of carboxylic acids to carboxylic acid chlorides ( ), carbamates to isocyanates ( ), amino-acids to isocyanato acid chlorides and arylamine hydrochlorides to isocyanates In these reactions chlorodimethylformiminium chloride is being used, because it is readily available. However, other imidoyl halides could react in a like manner. 

Formation of quinoline derivatives by prolonged heating of arylamine hydrochlorides with ketones with or without use of aluminum chloride or phosphorus pentachloride ... 

As expected, 4-aryloxy groups in pyridine oxides can be replaced by amines . 4-Alkoxy709 and 4-aryloxy-groups706 in quaternary pyridinium salts are readily replaced. In contrast to 4-phenoxypyridine, 4-phenoxy-pyridine hydrochloride does not react with arylamine hydrochlorides, presumably because of the lowering of the nucleophilic power of the amine... 

Monosubstituted [ CJguanidines are straightforwardly available through treatment of [ CJcyanamide with alkyl or arylamine hydrochlorides in n-butanol at elevated temperamre under anhydrous conditions, as in the preparation of l-(2-methyl-5-nitrophe-... 

The experimental procedure can be varied by the use of reagents which will give biguanides in situ and thus form the required triazine. Examples include 493, 554) the interaction of arylamines (e.g. p-chloro-aniline hydrochloride) and cyanoguanidine, followed by acetone and hydrochloric acid. Acetone may be replaced by its bisulphite compound, by diethyl acetal or by isopropenyl acetate, but p-chlorophenylbiguanide fails to condense 113) with acetone diethyl acetal at 130°. Under the correct acid conditions, the isomeric p-chloroanilino-triazine (CXXV) is not formed on the other hand, the free p-chlorophenylbiguanide base did not react with acetone in the absence of a catalyst. 

It may be noted that some aromatic amines react with 5 per cent hydrochloric acid to form insoluble hydrochlorides the latter sometimes dissolve upon warming slightly and diluting with water. The appearance of the solid will usually show whether the arylamine has undergone a change the solid should be... 

Tertiary arylamines were prepared in good yields by hydrogenation of an alcoholic solution of a nitro compound and an aldehyde over Raney Ni in the presence of triethy-lamine hydrochloride or, better, over platinum oxide in the presence of acetic acid (eq. 6.22).48 Base metal and platinum metal sulfides are also effective to the reductive alkylation of nitro compounds with ketones36,37 as in an example shown in eq. 6.23. 

Substituted quinazolin-4-amines 12 are prepared in a one-step synthesis by heating quin-azolin-4(3/f)-one in a mixture of phosphorus pentoxide, A,A-dimethylcyclohexylamine (DMCA), and an appropriate amine or amine hydrochloride. Dimethylamine and primary arylamines are used as hydrochlorides, whereas with secondary amines, heterocyclic amines, benzyl- and furfurylamines it is necessary to use the free amine rather than the amine hydrochloride. 

The reactions of A-chloroalkylphosphazenes with hydroxylamine hydrochloride to give (73) proceed in a similar manner. Derivatives of (73) were obtained by reactions with arylamines, with sodium aryloxides, and with acetic (or formic) acid. The latter is noteworthy in that the proton of the hydroxy-group in (74) does not migrate to nitrogen. 

From the results of early studies by Sorokin and Irvine and McNicoll, i t was long believed that only aldoses react readily with arylamines research on these derivatives was revived by Barry and Honeyman in 1950. As a result of careful experimentation, the reaction conditions were so changed that the product was obtained crystalline, and even derivatives could be prepared. At first, a mixture of D-fructose and the amine hydrochloride in anhydrous ethanol was boiled, but this method was criticized in... 

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