N-Phenylsulfonyl indole

Tartaric acid, L-Lithium bromide N-Phenylsulfonyl indole 1,2-Dibromoethane Trifluoroacetic acid 1-Chloroethyl chloroformate Formaldehyde Allyl bromide... 

Zhou P, Yan Y, Bernotas R, et al. 4-(2-Aminoethoxy)-N-(phenylsulfonyl) indoles as novel 5-HTe receptor ligands. Bioorg Med Chem Lett 2005 15 1393-1396. 

Table 27 Halogen-metal exchange reactions of 3-iodo-N-(phenylsulfonyl)indole (6)...

Nitration of indole is not possible with HNO3/H2SO4 instead, polymerization is observed. Indoles substituted in the 2-position can be nitrated either in the 3-position (benzoyl nitrate) or in the 6-position (HNO3/H2SO4). (N-Phenylsulfonyl)indole or (N-benzyl)indole are readily nitrated by HNO3/acetic anhydride in the 3-position [133] ... 

Srinivasan found that the typical stoichiometric Pd(OAc)2 conditions effect cyclization of 2-(N-arylaminomethyl)indoles to aryl-fused p-carbolines in low yield [e.g., 51 to 52] [73]. Similar to the chemistry observed with N-(phenylsulfonyl)pyrrole, 1,4-naphthoquinone also undergoes Pd(OAc)2 oxidative coupling with A-(phenylsulfonyl)indole to give 53 in 68% yield [74],... 

A solution of 2-lithio-l-(phenylsulfonyl)indole was prepared by adding 1-(phenylsulfonyl)indole (11.7 mmol) dissolved in THF (30 ml) to a solution of LDA prepared from (i-Pr)2NH (1.12 eq) and n-BuLi (1.05 eq) in THF (30 ml) at — 75°C. The solution was stirred at — 70°C for 1 h and then warmed slowly to 5DC over 1 h. The solution was recooled to — 78JC. A solution of acetaldehyde (l.OOg, 22.7 mmol) in THF (5 ml) was added rapidly by syringe. The reaction mixture was then allowed to come slowly to room temperature and poured into 1% HC1 (350 ml). The solution was extracted with CH,C12 (3 x 250 ml) and the combined extract was washed with water (400 ml) and brine (2 x 400 ml) and then dried over K2C03. The solvent was evaporated in vacuo and the residue purified by chromatography to give the product (3.28 g, 93%). 

Several methods for synthesizing N-protected (usually with electron-withdrawing groups) 2-and 3-haloindoles have been developed and the resulting haloindoles are much less prone to decomposition than the unsubstituted compounds. Bromination of N-(phcnylsulfonyl)indole (3), which is readily available via lithiation [9, 10] or phase-transfer chemistry [11, 12], affords 3-bromo-l-(phenylsulfonyl)indole (4) in nearly quantitative yield [12]. 

Engler has noticed an interesting dichotomy in his indole synthesis involving benzoquinone monoimides <97TL6135>. For instance, while reaction of the quinone monoimide 96 with N-phenylsulfonyl enol ethers in the presence of Ti(IV) Lewis acid catalysts affords the expected tetrahydrocarbolines 97, reactions promoted by BF3 produce substituted benzofurans. 

The selective C2-lithiation of 3-substituted-l-(phenylsulfonyl)indoles 37 is a common strategy for the synthesis of 2,3-disubstituted indoles 39. The bases that have been used to prepare 3-alkyl-2-lithio-AA-(phenylsulfonyl) indoles 38 include LDA, n-butyllithium, scc-butyllithium, and phenyllithium... 

Other reports on the [3+2] cycloadditions of indoles and nitrile oxides focus on intermolecular reactions. For example, Gribble [80] has investigated the reaction of (phenylsulfonyl)-2-(tri-n alkylstannyl)indoles 169 with tetranitromethane to give the novel isoxazolo[5,4-b]indole derivative 173 (Scheme 49). The mechanism cascade is thought to proceed through the degradation of the dinitromethyl anion to a nitrile oxide 171, followed by a 1,3-dipolar cycloaddition to form a nitroindole intermediate 172 and subsequent loss of nitrous acid or SnR3N02. Treatment of the isoxazole 173 with base then leads to the formation of the oxindole tautomer 175 as the major product. 

An example is the metalation/alkylation of (l-phenylsulfonyl)indole, which (after removal of the N-sulfonyl moiety by alkaline hydrolysis) allows the directed synthesis of 2-alkyl indoles 31. 

Recently, Li successfully conducted the Suzuki and Stille reactions on the pyrazine ring of 3-bromoquinoxalin-2-ylamines [51]. Indolylquinoxaline 92 was obtained from the union of 3-bromoquinoxalin-2-ylamine 90 and l-phenylsulfonyl-2-tri-n-butylstannyl-l//-indole (91). A wide variety of heterocyclic stannanes bearing various functional groups underwent Stille coupling with 90 under the same conditions to give the corresponding adducts in 72-98% yields. 

Diazo-1 -(4-methyl-phenylsulfonyl)-E14b, 1300 (aus N-NO —amid) Indol... 

The saltlike alkali metal compounds of indole react with electrophiles such as haloalkanes, acyl halides, sulfonyl halides and trimethylchlorosilane to form the corresponding 1-substituted indoles. 1-Benzylindole isomerizes to 2-benzylindole when heated in polyphosphoric acid [47]. 1-Phenyl-sulfonylindole is lithiated in the 2-position by n-butyllithium. Subsequent alkylation with haloalkanes and cleavage of the phenylsulfonyl residue with sodium hydroxide yields 2-alkylindole. 

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