Indole-3-carboxylic acid, 1-methoxy

Esters of 2-(2-azidophenyl)ethyl alcohol are photolyzed under a high-pressure mercury lamp to a reactive nitrene intermediate which, following insertion into the alkyl side-chain, undergoes elimination to give the free carboxylic acid (up to 32%) and producing indole. The photochemical release was somewhat improved (65-80%) when 5-azido-4-(hydroxy-methyl)-l-methoxy naphthalene was used (see Scheme 27). 

To a solution of the S-(+)-4-acethoxy-9-[2-(5-ethyl-l,2,3,6-tetrahydro-pyridin-3yl)-l-(lH-indol-2-yl)-l-methoxycarbonyl-ethyl]-3a-ethyl-5-hydroxy-8-methoxy-6-methyl-3a,4,5,5a,6,ll,12,12b-octahydro-lH-6,12a-diaza-indeno[7,l-ca]fluorene-5-carboxylic acid methyl ester in dioxane and glacial acetic acid was added 37% aqueous formaldehyde and the mixture stirred at 35°C for 24 h. The solution was evaporated in vacuo and the residue suspended in chloroform and washed with cold aqueous 5% K2C03 solution. The chloroform layer was dried (MgS04), filtered, and evaporated. The residue was chromatographed eluting with EtOAc/MeOH, 10% NH4OH to give the product navelbine. 

In a similar heterocyclic quinodimethane ring construction strategy, the hexacyclic adducts (64) were isolated in good yield upon condensation of appropriately functionalized indole imines with ( )-bicyclo[2.2.1]hept-5-ene-2-carboxylic acid chloride (Equation (35)) (88JA2242). In a demonstration of the utility of this new method for indole alkaloid synthesis, further transformations conducted on compound (64 R = R2 = H, R3 = Et) were shown to lead to ( —)-16-methoxy-tabersonine. 

C111H15N3O5 0.5 CH4O, 3-Carbamoyl-1,2-dihydro-4-hydroxy-5-methoxy-3H-pyrrolo[3,2-e]indole-7-carboxylic acid methyl ester methanol solvate, 44B, 255... 

CA Index Name l//-Indole-6-carboxylic acid, 2-[4-[bis [2- [(acetyloxy)methoxy] -2-oxoethyl] amino] -3- [2- [2-[bis[2-[(acetyloxy)methoxy]-2-oxoethyl]amino]-5-me-thylphenoxyjethoxyjphenyl]-, (acetyloxy)methyl ester... 

Beccalli et al. reported a synthesis of carbazomycin B (261) by a Diels-Alder cycloaddition using the 3-vinylindole 831 as diene, analogous to Pindur s synthesis of 4-deoxycarbazomycin B (619). The required 3-vinylindole, (Z)-ethyl 3-[(l-ethoxy-carbonyloxy-2-methoxy)ethenyl]-2-(ethoxy-carbonyloxy)indole-l-carboxylate (831), was synthesized starting from indol-2(3H)one (830) (620). The Diels-Alder reaction of the diene 831 with dimethyl acetylene dicarboxylate (DMAD) (535) gave the tetrasubstituted carbazole 832. Compound 832 was transformed to the acid 833 by alkaline hydrolysis. Finally, reduction of 833 with Red-Al afforded carbazomycin B (261) (621) (Scheme 5.99). 

Cyclization of the anilide 213 using TiCU produced the 3-chloro-substituted oxindole 214 (Equation 69), whereas a similar reaction induced by BF3-OEt2 gave the corresponding methoxy-substituted derivative <1998T4889>. Lewis acids have also been used in an approach to indole-2-carboxylates based on cyclization of (Z)-A(A -dimethyl-aminopropenoates derived by exposure of A -arylglycinates to DMEDMA <2006SL749>. 

Replacement of methoxy groups by chlorine atom(s) in the phenylhydrazine ring also leads to a mixture of products, some of which are anomalous. The equation shows the main product when 2,6-dichlorophenylhydrazine reacts with ethyl pyruvate, no indole is formed in the presence of ethanolic hydrogen chloride, but zinc chloride-acetic acid gives a low yield (4.9%) of ethyl 5,7-dichloroindole-2-carboxylate [3764]. A study of the indolization of a-phenyl-a-... 

A stirred suspension of K-fert-butoxide in benzene treated with a soln. of methyl 5-methoxy-6-methyl-2-indolecarboxylate in benzene followed by methyl acrylate, refluxed 2 hrs., then stirred 63 hrs. at room temp. methyl 2,3-dihydro -7-methoxy-6-methyl-1- oxo-IH-pyrrolo[1,2-a]indole-2-carboxylate (Y 63-82%) refluxed ca. 18 hrs. in 95%-acetic acid 2,3-dihydro-7-methoxy-6-methyl-lH-pyrrolo[1,2-a]indol-l-one (Y 86%). F. ring closure s. G. R. Allen, Jr., J. F. Poletto, and M. J. Weiss, J. Org. Ghem. 30, 2897 (1965) ring closure with transesterification s. J. Org. Ghem. 30, 2910. 

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