Ethoxycarbonyl indole

In situ quaternization method ethyl 2-(ethoxycarbonyl)-2-formamido-3-(indol-3-yl)propanoate[7,8J... 

Directed thallation has been useful for synthesis of some 4- and 7-substituted indoles. Electrophilic thallation directed by 3-substituents is a potential route to 4-substituled indoles. 3-Formyl[7], 3-acetyi[8] and 3-ethoxycarbonyl[7] groups can all promote 4-thallation. 1-Acetylindoline is the preferred starting... 

The classic Reissert indole synthesis, involving the reducdve cyclization of o-ni-trophenylpymvic acid, has been used for synthesis of 2-ethoxycarbonyl-4-alkoxymethylindo-les The modified Reissert reacdon, involving the reducdve cyclizadon of an o-rdtrophenyl acetoaldehyde, has been adapted to solid-phase synthesis... 

Ethyl 3-azido-l-methyl-177-indole-2-carboxylate 361 is prepared in 70% yield by diazotization of amine 360 followed by substitution of the created diazonium group with sodium azide. In cycloadditions with nitrile anions, azide 361 forms triazole intermediates 362. However, under the reaction conditions, cyclocondensation of the amino and ethoxycarbonyl groups in 362 results in formation of an additional ring. This domino process provides efficiently 4/7-indolo[2,3-i ]l,2,3-triazolo[l,5- ]pyrimidines 363 in 70-80% yield (Scheme 57) <2006TL2187>. 

Heat 1.1 g 2-ethoxycarbonyl-5-hydroxyindoIe(5-OH-indole and perhaps 5-OH-DMT will work) and 0.9 g powdered AICI3 at 145° in orthodichlorobenzene. Add 2-3 ml acetylchloride and keep the temperature at 145-150° for 2 hours. Cool and hydrolyze with ice cold 2N HCI. Extract with chloroform and dry, evaporate in vacuum to get 4-acetyl-2-ethoxy-carbonyl-5-hydroxyindole in ca. 50% yield. This paper also gives a method for borminating the starting cpd. in the 4 position. 

Chandrasekhar and colleagues used Af-acyl-Af, 0-bis(ethoxycarbonyl)hydroxylamines in a similar procedure to prepare amines. Aromatic Af-hydroxyimide derivatives were used by Marzoni and Varney " and Giitschow " to synthesize benz[crf]indol-2(l//)-one and 1-benzoxazin-4-one derivatives, respectively, via Lossen rearrangements. Both Af-benzyloxy and A-mesyloxy derivatives were used. 

The related cyclization of 2-ethynylanilines 67 also represents one of the usefiil methods for the synthesis of 2-substituted indoles since the precursors are easily prepared from 2-haloanilines 66 by Pd-catalyzed cross-coupling with terminal alkynes. Althou cyclizations of such alkynes are normally effected using Cu(I) or Pd(II) species, Sakamoto showed that in the absence of such metals, base catalysis (e.g., NaOEt) alone can accomplish the same goal. This author now reports that tetrabutylammonium fluoride (TBAF) is capable of inducing cyclization to the indoles 68 without affecting functionalities such as bromo, cyano, ethoxycarbonyl, and ethynyl <99JCS(P1)529>. 

An alternative approach to the PQQ-triester 130, a precursor to the cofactor PQQ, was developed starting with diethyl 4-oxopent-2-ynedioate 128 <1996HCA658>. Diastereoselective formation of diethyl (Z)-2-(2-(ethoxycarbonyl)-5-methoxy-l/7-indol-6-ylamino)-4-oxopent-2-enedioate 129 followed by acid-catalyzed cyclocondensation gave the target 130 (Scheme 19). 

Hydroxy-5-(2-indolyl)-l,3,4-oxadiazole171 allgemeine Arbeitsvorschrift 0,01 mol des N-substituierten 2-Hydrazinocarbonyl-indols erhitzt man mit 1,09 g(0,01 mol) Kohlensaure-chlorid-ethylestcr in 4 m/Ethanol 24 h unter RuckfluB und isoliert nach dem Abkuhlen die 2-Ethoxycarbonyl-l-(2-indolyl)-hydrazinc, die mit Ethanol gewaschen und umkristallisiert werden. Danach suspendiert man diese in 10 ml Diphcnylether, erhitzt 3 h unter RuckfluB, kiihlt ab und versetzt mit Petrolether (60-80°). 

Ethoxycarbonyl-2-hydroximino-ethyl) -2-oxo-2J-dihydro-indol 50% Schmp. 184° (Ethanol/Cyclohexan)... 

Carboxy 7 chloro-2 (ethoxycarbonyl)indole-3-propanoic acid. 68... 

Fused pyrroles have been prepared by the condensation of an amino group with a suitably positioned carbonyl function. Thus, reduction of ethyl (3-nitro-2-thienyl)pyruvate (226) with tin(IV) chloride gave 5-ethoxycarbonyl thieno[3,2-6]pyrrole (47), by the spontaneous cyclization of the intermediate amino derivative (227 Scheme 76) (64JOC2160). The formation of indolo[3,2-6]indole (229), a dibenzannelated pyrrolopyrrole, by the cyclization of (228) with tin(IV) chloride (Scheme 77) is an example of a case where reduction of the imino function in the starting material is necessary before cyclization will occur (78AHC(22)183). 

Indole, 3-ethoxycarbonyl-N-phenyl-geometry, 4, 162 Indole, 2-ethoxy-1-methyl-cycloaddition reactions with dimethyl acetylenedicarboxylate, 4, 268 reactions... 

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