Diphenylamine synthesis

Both, XantPhos and DPEPhos are remarkable Ugands which were developed by van Leeuwen and coworkers [50]. These Ugands are especiaUy useful in the coupUngs of various amine derivatives, such as amides [51, 52], hydrazines [53], oxazoUdinones [54] and ureas [55]. Furthermore, appUcations of XantPhos to the diphenylamine synthesis [48], and coupUngs of alkylarylamines [56], as weU as... 

In the synthesis of commercial sulfur-heterocycles two interesting reactions are used (i) diphenylamines may be connected by a sulfur bridge in the orfho-positions (ii) the amino grouping of sulfonamides undergoes condensation reactions with neighboring imino- and amide groups. 

The cyclized products 393 can be prepared by the intramolecular coupling of diphenyl ether or diphenylamine(333,334]. The reaction has been applied to the synthesis of an alkaloid 394[335]. The intramolecular coupling of benzoyl-A-methylindole affords 5-methyl-5,10-dihydroindenol[l,2-b]indol-10-one (395) in 60% yield in AcOH[336]. Staurosporine aglycone (396) was prepared by the intramolecular coupling of an indole ring[337]. 

BERNTHSEN Acndine synthesis Acndine synthesis from diphenylamine and cartxixylic acids... 

At the same, time attempts to apply this approach to the synthesis of phenotel-lurazine and its A-methyl derivative using diphenylamine and A-methyldiphenyl-amine as starting materials failed [83JOM(251)223 85KGS757]. The parent phe-notellurazine 35 (M = NH, R = R = H) has been prepared in low yield (7%) by refluxing an acetic acid solution of 4-trichlorotellurodiphenylamine 39 (89H1007). 

Polyphosphoric acid is preferred except in the case of the formamido compounds 1, R3 = H. The synthesis fails with diphenylamine derivatives lacking a substituent on nitrogen, benzimidazoles being produced (see Houben-Weyl, Vol. E8c, p 231 flf). 

Phenothiazines are well-known as intermediates for pharmaceuticals, and are also active as insecticides and antioxidants. These compounds are usually prepared by the thiation of diphenylamines with elemental sulfur. In this context, the group of Toma has elaborated a synthesis of 3-phthalimidophenothiazine, as shown in Scheme 6.265 [455]. Using a variety of high-boiling solvents under conventional thermal reflux conditions, low isolated yields of the desired product were obtained. The highest conversion and isolated product yield (55%) was achieved by microwave irradiation of a mixture of the starting N-(4-phenylaminophenyl)phthalimide with... 

J. Cho, A. Kimoto, M. Higuchi, and K. Yamamoto, Synthesis of diphenylamine-substituted phenylazomethine dendrimers and the performance of organic light-emitting diodes, Macro Chem. Phys., 206 635-641 (2005). 

Most syntheses of naturally occurring phenazines, though, are based on a two-step elaboration of the central heterocycle of the phenazine [78]. The first key step involves the generation of orf/zo-monosubstituted 88 or orf/zo, ortho -disubstituted diphenylamines 89-91 via nucleophilic aromatic substitution. Ring formation is then achieved by means of reductive or oxidative cyclization, for which a number of efficient methods are available. The main flaw of this approach is the synthesis of the substituted diphenylamines via nucleophilic aromatic substitution, as this reaction often can only be performed under strongly basic reaction conditions and at high temperatures. In addition, the diphenylamines required may only be achieved with certain substitution patterns with high yields. 

Lin and Zhang reported the synthesis of l-hydroxy-3-methylcarbazole (23) starting from the nitro derivative 625 (578). This synthesis uses a Buchwald-Hartwig amination for the synthesis of the diphenylamine 628. After protection of the hydroxy group in the nitrophenol 625 as a benzyl ether, the nitro group was reduced to the corresponding amino derivative 627. Amination of 627 with iodobenzene under Buchwald-Hartwig conditions afforded the diarylamine 628. Palladium(ll)-mediated cyclization of 628 led to the carbazole derivative 629, albeit in low... 

The method that has been most utilized for the preparation of aromatic carbazoles from noncarbazole precursors is the dehydrogenation of a tricyclic indole, usually a 1,2,3,4-tetrahydrocarbazole. The synthesis of the latter s is outside the scope of this article. The next most used precursors are biphenyls with an ortho nitrogen substituent, and the next, diphenylamines the synthesis of these precursors is also not dealt with in detail here. Finally, a variety of approaches utilizing precursor indoles have been described some of these have been used only once, whereas others have been used often enough that they can be described as general. 

Many acridines and benzacridines have been synthesized by the Bernthsen reaction (l884LA(224)l) in which a diphenylamine is heated with a carboxylic acid and zinc chloride, with or without aluminum chloride. The reaction has been reviewed (73HC(9)141), and will be outlined here. The yields are not generally high one of the better examples is the synthesis of 2-chloro-9-methylacridine (312) (63BCJ1477). In the synthesis of the... 

Methylnitramine decomposes explosively in contact with concentrated sulphuric acid. It is evolved when aniline reacts with tetryl, a diphenylamine derivative (p. 51) is produced simultaneously. Methylnitramine reacts with picryl chloride to form tetryl. The structure of tetryl (p. 40) was first proved by this synthesis. 

The addition of alkylated phenothiazines, e.g., decylphenothiaz-ine or tetradecylphenothiazine still improves the performance (67). Alkylated phenothiazines are synthesized by the reaction of an alkylated diphenylamine with elementary sulfur. The synthesis is shown in Figure 6.9. 

The Ic pattern for carbazole synthesis arises primarily in the dehydrogenative cyclization of diphenylamines. This cyclization can be accomplished photolytically, with an oxygen sensitive intermediate having been detected (equation 58) (81JA6889). Preparative work with substituted diphenylamines has resulted in rather variable yields, depending upon particular substituents. This variability may be the result of alteration in the dominant photochemical process with substituent changes. 

Generally high yields of substituted carbazoles can be obtained by oxidative cyclization of diphenylamines using Pd(OAc)2 to effect cyclization (equation 59) (75JOC1365). This method has been used, for example, to close the carbazole ring in the synthesis of the anti-tumor alkaloid ellipticine (equation 60) (80TL3319). 

JOURDAN-UIIMANN-GOLDBERG SYNTHESIS. Synthesis of substituted diphenylamines. The reaction products can be used as intermediates in the synthesis of acridones. 

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