A -Methylindole

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]. 

Apart from the syntheses already quoted as of possible biological interest, mention must be made of a series which are primarily of chemical interest. Kermack, Perkin and Rob mson prepared norharman, i.e., /S-carboline (VII) by warming A-methylindole-2-carboxyacetalylamide (XVIII) with alcoholic hydrogen chloride, thereby converting it into 2-keto-l-methyl-2 3-dihydro-/S-carboline (XIX), which on distillation... 

Similarly, iV,A/ -dimethyl-3,3 -bisindolylmethane (169) has been used in a related experiment, where treatment thereof with trifluoroacetic fflihydride (TFAA) in diethyl ether at room temperature yielded a mixture of products from which the trifluoromethyl-substituted indolo[3,2-b]carbazole 170 was isolated as the major pentacyclic component, accompanied by the hydroxy derivative 171 as well as small amounts of the indolo[2,3-h]carbazole 146 (Scheme 20). The precursor 169 could also be prepared in situ from A-methylindol-3-methanol under... 

This is the most convenient method of preparing indole-3-acetic acid if an agitated autoclave is available. The method can be used to prepare other indole-3-acetic acids from a-hydroxy acids. For example, a-methylindole-3-acetic acid has been prepared by condensing indole with lactic acid. 

Methylindole, 40, 68 a-Methylindole-3-acetic acid, 44, 66 Methyl iodide, methylation of dihydroresorcinol with, 41, 57... 

Experiment. E. Fischer s Indole Synthesis.—Mix 2 g. of phenylhydrazine with 2 c.c. of acetone in a test tube. Water is eliminated and a turbidity appears. Suspend the tube in the boiling water bath for forty-five minutes, then add 6 g. of dry zinc chloride and heat the mixture for a few minutes with stirring in an oil bath at 180°. Now wash the dark-coloured melt into a small round-bottomed flask with four volumes of dilute hydrochloric acid and separate the resultant a-methylindole by distillation with steam. The substance collects as an oil which soon solidifies. After drying crystallise it from a little petrol ether. Melting point 59°. 

The excellent chemoselectivity achieved with catalyst 153r may be attributed to its steric properties the bulky 3,3 -silyl substituents (R = SiPhj) ensure an effective shielding of the carbonyl group and thus prevent 1,2-addition. In the presence of catalyst 153r (5 mol%), the reaction of A-methylindoles 151 and p,y-unsaturated a-ketoesters 152 furnished the 1,4-addition products 155 in moderate to good yields and enantioselectivities (43-88%, 80-92% ee) (Scheme 64). 

Novel axially chiral bis-arylthioureas [e.g. (35)] catalyse the asymmetric substitution of indole and A-methylindole by nitroalkenes.41 2-Nitroethenylcyclohexane is ... 

The usefulness of relaxation measurements as a probe for charge-transfer complexation was investigated for the pair trinitrobenzene and methylindole (Blackburn and Friesen, 1977). On addition of trinitrobenzene to a methylindole solution the 13C 7) values of methylindole decrease, an... 

The first proton to be removed from A-methylpyrrole by -butyllithium is from an -position a second deprotonation occurs to give a mixture of 2,4- and 2,5-dilithiated derivatives. In both furan and thiophene, initial abstraction of a proton at C(2) is followed by proton abstraction from C(5). A-Methylindole, benzo[ ]furan, benzo[ ]thiophene, selenophene, benzo[ ]selenophene, tellurophene, and benzo[ ]tellurophene similarly yield 2-lithio derivatives. 

Competitive metallation experiments with A-methylpyrrole and thiophene and with A-methylindole and benzol] thiophene indicate that the sulfur-containing heterocycles react more rapidly with -butyllithium in ether. The comparative reactivity of thiophene and furan with -butyllithium depends on the metallation conditions. In hexane, furan reacts more rapidly than thiophene but in ether, in the presence of tetramethylethylenediamine (TMEDA), the order of reactivity is reversed. 

The decisive role of DABCO was also seen in the analogous reactions of A -methylindole (Equation 202). Treatment of the latter with S2CI2 (5 equiv) and DABCO (5 equiv) gave the 2,3-dichloroindole 811 in high yield (78%), but with a deficiency of S2CI2 (0.8 equiv) in the absence of a base the only product was the unchlorinated pentathiepin 812 in 72% yield. 

Photolysis of phenylselenomalonates in the presence of an excess of indole or A -methylindole led to the desired substituted products 1019 in poor yield (25-28%) (Scheme 197) <1999TL2677>. 

In the present context, the term electron rich alkenes refers primarily to enol ethers, enol sulfides, and A-vinylamides or A-vinylamines. Such alkenes are typically much more readily ionizable than are simple alkenes. The conversion of these substrates to the corresponding (highly electron deficient) cation radicals represents a sharp Umpolung. The Diels-Alder additions of tra j -anethole, phenyl vinyl ether, phenyl vinyl sulfide, 1,3-dioxole, and A-methylindole to 1,3-cyclohexadiene have been reported (Scheme 22) [49, 52]. 

A simple two-step synthesis of benzo[b]thiophene-2(3//)- (43) and -3(2//)-ones (44) has been reported (70JCS(C)1926) (Scheme 16). Similar results are also obtained by starting with A-methylindole (45). Compound 46 is obtained in a one-pot reaction in moderate yield (87MI1) (Scheme 17). 

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