Oxindoles from indoles

Although some efforts are being made to develop EMRs based on the immobilization of peroxidases onto the membrane [106, 112], the most applied configurations correspond to the use of direct contact reactors for wastewater treatment, with SBP and MnP applied to effluents containing both phenols [74] and dyes [8, 85]. Some attempts were made to apply an EMR for the synthesis of oxindole from indole by CPO [86]. However, the reactor was only stable for a short period (10 residence times). Afterward, the polymerization of oxindole yielded a solid substance, which blocked the membrane, causing enzyme deactivation and the reduction of the total turnover numbers compared to those obtained in batch assays. 

Oxindoles from indoles via ]-(2-indolyl)pyridinium salts 4-Carboxy-3,4-dihydrocarbostyrils from 3-indoleacetic acid esters... 

N-Bromosuccinimide palladium-carbon Oxindole- from indole-3-alkanoic acids... 

Ha.logena.tlon, 3-Chloroindole can be obtained by chlorination with either hypochlorite ion or with sulfuryl chloride. In the former case the reaction proceeds through a 1-chloroindole intermediate (13). 3-Chloroindole [16863-96-0] is quite unstable to acidic aqueous solution, in which it is hydroly2ed to oxindole. 3-Bromoindole [1484-27-1] has been obtained from indole using pytidinium tribromide as the source of electrophilic bromine. Indole reacts with iodine to give 3-iodoindole [26340-47-6]. Both the 3-bromo and 3-iodo compounds are susceptible to hydrolysis in acid but are relatively stable in base. 

Folkes, L. K., Rossiter, S., and Wardman, P., 2002, Reactivity toward thiols and cytotoxicity of 3-methylene-2-oxindoles, cytotoxins from indole-3-acetic acids, on activation by peroxidases, Chem. Res. Toxicol. 15 877-882. 

HINSBERG - ST0L16 lndole-Oxindole Synthesis Indole synthesis Iron anilines and glyoxal (Hinsberg). oxindole synthesis from anilines and a-haloacyl halides (Stolle). 

A variety of methods have been developed for the selective installation of chirality at oxindole C3 that involve transfer of functionality from indole C2. The Vedejs group has prepared a small collection of chiral DMAP (4-(lV,A-dimethylamino) pyridine) derivatives bearing conformationally restricted side chains that have been employed as nucleophilic catalysts to direct the transfer of indolyl C2 acetate or carboxylate groups to oxindole C3 with excellent enantiofacial selectivity [15]. As illustrated in Scheme 1, indolyl acetate 1 was converted to the chiral oxindole 3 (94%, 91% ee) using DMAP catalyst 2, while the opposite sense of enantioselec-tivity was observed when indolyl carboxylate 4 was treated with DMAP catalyst 5 to afford 6 as the major oxindole adduct (99%, 94% ee). In addition to probing modifications of the DMAP side chains, it was demonstrated that the overall rate of the reaction catalyzed by DMAP 2 was decreased when the indolyl acetate 1 contained a branched isopropyl substituent at C3 however, good enantioselectivity was observed with the branching substituent (82%, 94% ee). It was also... 

Racemic entry to quaternary C3 hydroxy oxindoles from C3-substituted indoles has been achieved using a variety of oxidants including dimethyldioxirane [56], CeCl3 7H20/IBX [57], or PCC (pyridinium chlorochromate) with polyaniline salt (PANl) as acid catalyst [58]. 

Boron, Phosphorus, and Selenium Compounds. Oxone has been used to oxidize carbon-boron bonds during the work-up of hydroboration reactions to obtain high yields of the resultant alcohols (eq 73). Aqueous Oxone/acetone oxidizes electron-poor and electron-rich aromatic and aliphatic boronic acids and esters to the corresponding alcohols rapidly and efficiently (eq 74). A one-pot procedure for the synthesis of iweta-substituted phenols from benzenes has been developed, and a similar strategy has been devised for the synthesis of Boc-oxindoles from Boc-indoles. i3i... 

Oxindole and indole alkaloids corynoxeine, hirsutine, and hirsuteine from uncaria Uncaria rhynchophylla Miq.) as the main compounds of the extract destabilize the formation of Ap aggregates [185]. They also have a neuropro-tective effect and inhibit glutamate-induced neurotoxicity in the cells of the cerebellum [186]. 

Rearrangements related to the Bartoli-indole synthesis have also been designed for the preparation of ortho-alkylated anilides and oxindoles from O-acetyl-JV-arylhydroxylamines. 

Khorshidi and Tabatabaeian (2010) used Ru(III)-exchanged FAU-Y zeolite as an efficient reusable heterogeneous catalyst for preparation of oxindoles from condensation reaction of indoles with isatins nnder very mild reaction conditions (Scheme 2.11). In evaluating the reusability of the solid catalyst, only 8% loss of efficiency in terms of the product yield was observed after five runs, which promises minimization of waste. 

The heterogeneous catalyst kaolin, preloaded with KOH, was used for the synthesis of 3-hydroxy-3-indolyl oxindoles from isatins and indoles in good to excellent yields by Srihari and Murthy (2011) (Scheme 2.15). The feasibility of the reaction was studied in various organic solvents such as CH2CI2, CH3CN, DMF, MeOH, and DMSO and found that the reaction did not proceed in CH2CI2, DMF, and DMSO, whereas the... 

The preparation of oxindoles from yohimbines by rearrangement of chloroindolenine derivatives (i — ii) affords an unusually efficient route to the oxindole alkaloids from their corresponding indole counterparts, N. Finch and W. I. Taylor, J. Amer. Chem. Soc., 84, 1318 (1962) 84, 3871 (1962) J. Shavel and H. Zinnes, J. Amer. Chem. Soc., 84, 1320 (1962). 

The above reaction offers a convenient synthetic pathway to oxindoles from parent indoles bearing an aminoethyl side chain at the 3-position. The yields are almost quantitative, as checked with tryptophan, 5-fluoro-tryptophan, tryptamine and serotonin (727). 

Kobayashi, T., and N. Inokuchi A New Method for the Preparation of Oxindoles from Parent Indoles. Tetrahedron 20, 2055-2058 (1964). 

Gassman and co-workers developed a synthetic route from anilines to indoles and oxindoles which involves [2.3]-sigmatropic rearrangement of anilinosul-fonium ylides. These can be prepared from Ai-chloroanilines and ot-thiomcthyl-ketones or from an aniline and a chlorosulfonium salt[l]. The latter sequence is preferable for anilines with ER substituents. Rearrangement and cyclizalion occurs on treatment of the anilinosulfonium salts with EtjN. The initial cyclization product is a 3-(methylthio)indole and these can be desulfurized with Raney nickel. Use of 2-(methylthio)acetaldehyde generates 2,3-unsubstituled indoles after desulfurization[2]. Treatment of 3-methylthioindoles with tri-fiuoroacetic acid/thiosalieylie acid is a possible alternative to Raney nickel for desulfurization[3]. 

During the past two decades a great number of papers have been published on the isolation, structure elucidation, synthesis and transformation, biogenesis, chemotaxonomy, and pharmacology of indole alkaloids. In this chapter we summarize the new results that appeared from 1968 to mid 1984 for the cory-nantheine-yohimbine group of monoterpene indole alkaloids with greater emphasis on their chemistry, excluding the related oxindoles and heteroyohimbines. 

Indoles from isatins or oxindoles via diborane Synthesis 2,84 (1972)... 

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