7,7-Diphenyl indole

Bromination of the diphenyl indole derivative 316 with bromine in DMF or trimethylammonium bromide afforded the 7-bromo derivative 317. Reaction with allyl bromide or its derivatives gave A-allyl derivatives 318 that upon cyclization with palladium acetate gave 7,9-dimethoxy-l,2-diphenylpyrrolo[3,2,l-// ]quinoline derivatives 319 (92T7601) (Scheme 57). 

On the contrary, if jnst two positions in a cation-radical have the increased density of an nnpaired electron, dimerization nnderstandably follows a head-to-tail pattern. This is the case of 2,3-diphenyl indole (Check and Nelson 1978 Scheme 3.12). 

Recently, evidence for the transient ex istence of cation-radicals from simple pyrroles and indoles has been furnished by the observation of anodic regiospecific cyanation of these heterocycles.455 Both heterocycles are preferentially cyanated at the 2-position. Methyl side chains at these positions are also activated to cyanation and deuteration. Indole cation-radicals have been generated by photoionization in an aqueous medium.456 Unsubstituted at N, their lifetime in neutral solution is 10-6sec before they lose the N-proton however, it is longer in more acidic conditions.456 The photophysical properties of indole, its cation-radical, and neutral radical have been the subject of a recent theoretical analysis.457 On anodic oxidation of 2,3-diphenyl indole in acetonitrile, the initially formed cation-radicals dimerize to a product identified, primarily on the basis of 13C NMR, as 3-(5-indolyl)-indolenine (141).458... 

Substituted hydrazines yield the corresponding substituted in-dols for example, from diphenylliydrazine and acetone diphenyl-indol is formed ... 

Diphenyl-indol 20,468. 2.3.Diphenyl-indol 20, 520, II 334. 9-Benzyl-acridin 20. 520. 

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]. 

Azido-2,3-diphenyl-3//-indole (510) gave mainly 2,3-diphenylquinoxaline (511) (MeaNCHO, reflux, 16 h 82%) = similarly. ... 

Methyl-37/-indoles react with 2 equiv of diethyl malonate in hot diphenyl ether to give pyranoindolizines such as 125. However, under the same conditions, 2-methvl-2.3-di hydro-1 //-indoles give the regioisomeric pyrrolopyrano-quinolines, for example, 126 (Scheme 35) <2003JHC297>. 

A final type of cyclopropenium cyanines is found in the azatriapentafulvalenium ions 145,146, and 147/148, which have been prepared93,112,113 from diphenyl and di-n-propyl cyclopropenone or ethoxy cation 75 and indole derivatives as well as from diphenyl methylthio cyclopropenium cation and phenyl-substituted pyr-roles114> ... 

Excellent ee-values (up to 94%) have been obtained for the hydrogenation of various 2-substituted N-acetyl indoles with an in-situ prepared rhodium catalyst modified with the trans-chelating diphosphine (S,S)-(R,R)-2,2"-bis[l-(diphenyl-phosphino)ethyl]-1,1"-biferrocene (Scheme 16.23) [88]. A strong base was required as co-reagent to observe both high conversion (TOFs of 50-100) and en-... 

Most of the early applications of palladium to indole chemistry involved oxidative coupling or cyclization using stoichiometric Pd(II). Akermark first reported the efficient oxidative coupling of diphenyl amines to carbazoles 37 with Pd(OAc)2 in refluxing acetic acid [45]. The reaction is applicable to several ring-substituted carbazoles (Br, Cl, OMe, Me, NO2), and 20 years later Akermark and colleagues made this reaction catalytic in the conversion of arylaminoquinones 38 to carbazole-l,4-quinones 39 [46]. This oxidative cyclization is particularly useful for the synthesis of benzocarbazole-6,11-quinones (e.g., 40). 

Trichloroethane, Trichloroethylene Dioxanol, see 1,4-Dioxane Dioxanone, see 1,4-Dioxane Dioxindole, see Indole 2,2 -Diphenic acid, see Phenanthrene Diphenyl disulfide, see Fonofos... 

Chlor-3,3-diphenyl-2-formyl-l-methyl-2,3-dihydro-indol 35%... 

The influence of a C-2 substituent upon the reaction course has been investigated. If only a 2-aryl group is present, as in 145 (R = H), then 4-quinolones 146 are formed (85H2375). But ferricyanide oxidation of 2,4-diphenyl derivatives resulted in the release of the 2-phenyl group and formation of the quinolones 147 instead of the exptected indole derivatives (83CCC2965). 

A number of reduction products of 2,8-dichloro-6,12-diphenyldibenzo[f>,/][l,5]diazocine (283) have been obtained (66JOC3356). LAH in ether gives mainly the frans-diphenyl-tetrahydro compound (282), whereas reduction in pyridine stops at the dihydro stage (284) (78%). Catalytic hydrogenation or zinc-acid reduction gives the tetracyclic indolo[3,2-6]indole system (286) which is readily oxidized back to the diazocine. Transannular cycliz-ation to (286) occurs on treatment of the dihydrodiazocine with NaH. Troeger s base derivatives, e.g. (287), were formed from the tetrahydro derivatives with formaldehyde. 

Lithiation can be diverted away from C-2 of indole by the use of a bulky N-substituent. Although 1-methylgramine is cleanly lithiated at C-2, l-(triisopropylsilyl)gramine is lithiated selectively at C-4 and can lead to useful 4-substituted indoles electrophiles include 1,2-dibromoethane, DMF, and diphenyl sulfide (Scheme 60) (93H(36)29). 

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