Indole 2,3-dimethyl

Read ions of Heterocyclic Enamines with a,p-Unsaturated Compounds Enamines react readily with compounds containing a double bone activated by electronegative groups. Addition of acrolein to 1-methyl-2 ethylidenepyrrolidine, followed by dehydrogenation, leads to 1,7-dimethyl indole (133) (Scheme 9) (215). 

An interesting addition of ethyl acrylate has been reported in the case of l-methyl-2-ethylidenepyrrolidine. An unsaturated amino ketone 144 is formed, which rearranges to 1,7-dimethyloctahydroindole (145) on reduction with formic acid, as established by dehydrogenation to 1,7-dimethyl-indole (Scheme 12) 217). 

The arylhydrazone 24 generally gives the 3-alkyl-2-methylindole 25 as major product. However, the indolization of ethyl methyl ketone has been reported to provide both 2,3-dimethyl indole and 2-ethyl indole. " ... 

To a stirred solution of 2,3-dimethyl indole (6, 1.45 g, 10 mmol, 1.0 equiv) and tetra-n-butylammonium sulfate (3.40g, 10 mmol, 1.0 equiv) in chloroform (150 mL) was added potassium hydroxide (50% aqueous solution, 20 mL) over 30 minutes. The stirring was continued for six hours, at which time the mixture was extracted with chloroform, the chloroform-water mixture was washed with water, and the organic layer concentrated. Silica gel chromatography provided 2,4-dimethyl-3-chloroquinoline (7, 1.52 g, 79% yield). 

With monochlorocarbene, pyrrole and indole underwent ring expansion to pyridine and quinohne, respectively, and 2,3-dimethyl-indole similarly gave 2,4-dimethylquinohne. ... 

Skatole (3-methylindole) readily forms a dimer hydrochloride with HCl in ether or with 15% aqueous HCl, as docs 1,3-dimethyl-indole. 3-n-Propylindole is also readily dimerized in dry ether/HCl/ ... 

When 1-methyl-, 1,2- and 1,3-dimethyl-indoles were oxidized on a platinum electrode in methanolic ammonium bromide solution, in addition to the oxidation products, products of nuclear bromination at the 3-and 5-positions were observed. 1,2- Dimethylindole (20) gave 3-bromo-1,2-dimethylindole (81CCC3278) [bromine in chloroform gave the same product (85CHE786)]. In acidic conditions the amidinium cation formed from 20 was brominated in the 5-position (Scheme 14). Acylated 2-aminoindoles reacted similarly in neutral media to give 3-bromo derivatives and when protonated to give 5-bromo products. Bromine in chloroform transformed l-methyl-2-dimethylaminoindole (21) into the 3-bromo derivative (85CHE782) (Scheme 15). 

N-, 2- and 2,3- alkylsubstituted indoles are reduced in acid solution to give good yields of the dihydroindolc [63]. Indole itself is polymerised under the acid conditions. Reaction was originally carried out in a medium of 60 % sulphuric acid at a lead cathode with no attempt made to find the optimum acid concentration. More recently, 20 % sulphuric acid has been proposed as the solvent in these reactions [64], Reduction of tetrahydrocarbazole 17 gives predominately cis-hexahydro-carbazole, the thermodynamically favoured isomer, along with 1 -2 % of the trans-isomer [65], 2,3-Dimethyl-indole yields a mixture of the cis- and trans-dihydro-indole isomers [63,66],... 

Miki and Hachiken reported a total synthesis of murrayaquinone A (107) using 4-benzyl-l-ferf-butyldimethylsiloxy-4fT-furo[3,4-f>]indole (854) as an indolo-2,3-quinodimethane equivalent for the Diels-Alder reaction with methyl acrylate (624). 4-Benzyl-3,4-dihydro-lfT-furo[3,4-f>]indol-l-one (853), the precursor for the 4H-furo[3,4-f>]indole (854), was prepared in five steps and 30% overall yield starting from dimethyl indole-2,3-dicarboxylate (851). Alkaline hydrolysis of 851 followed by N-benzylation of the dicarboxylic acid with benzyl bromide and sodium hydride in DMF, and treatment of the corresponding l-benzylindole-2,3-dicarboxylic acid with trifluoroacetic anhydride (TFAA) gave the anhydride 852. Reduction of 852 with sodium borohydride, followed by lactonization of the intermediate 2-hydroxy-methylindole-3-carboxylic acid with l-methyl-2-chloropyridinium iodide, led to the lactone 853. The lactone 853 was transformed to 4-benzyl-l-ferf-butyldimethylsiloxy-4H-furo[3,4- 7]indole 854 by a base-induced silylation. Without isolation, the... 

TRYPTAMINE, N,N-DIMETHYL INDOLE, 3-[2-(DIMETHYLAMINO)ETHYL] N,N-DIMETHYLTRYPTAMINE 3-[2-(DIMETHYLAMINO)ETHYL]INDOLE DESOXYBUFOTENINE NIGERINE... 

TRYPTAMINE, 2,a-DIMETHYL INDOLE, 2-METHYL-3-(2-AMINO)PROPANE 2-a-DIMETHYLTRYPTAMINE 2-METHYL-3-(2-AMINO)PROPYLINDOLE 2-Me-a-MT... 

TRYPTAMINE, 5-METHOXY-a,N-DIMETHYL INDOLE, 5-METHOXY-3-[2-(METHYLAMINO)PROPYL] 5-METHOXY-a,N-DIMETHYLTRYPTAMINE 5-METHOXY-3-[2-(METHYLAMINO)PROPYL]INDOLE a,N,0-TRIMETHYLSEROTONIN SEROTONIN, a,N,0-TRIMETHYL... 

Thionyl chloride has been used to introduce a sulfur atom in the preparation of an isothiazolo[4,5-6]indole derivative from TV-1-dimethyl indole-2-carboxamide. 2 83... 

The indole system has been the most extensively studied, particularly in regard to the mechanism of cyclization." It is noteworthy that in some instances an isomerization of the anilinoketone occurs, viz., R CH(NHRX OR" to R COCH(NHR)R From a preparative standpoint, the method is valuable in the formation of several indoles in excellent yields, e.g., 2,3-dimethyl indole (85%)" and 2-ethyl-3-methylindole (92%). Condensation of aniline derivatives of 2-chlorocyclohexanone yields the corresponding tetrahydrocarbazoles... 

Sulfonation of indole. Indole. I-methyl-, 2-methyl-, and 1.2-dimcthylindole are sulfonated by the reagent in refluxing pyridine at C3.3-Mcthylindole and 1,3-dimethyl-indole are sulfonated at Cj. 2,3-Dimethylindole does not react under these conditions. 

In a series of papers, Itahara established the utility of PdiOAc), in the oxidative cyclization of C- and A-benzoy I indoles, and two examples are shown [63]. Itahara also found that the cyclization of 3-benzoyl-1,2-dimethyl indole proceeds to the C-4 position (31% yield) [63a]. Under similar conditions, both 1-acetylindole and l-acetyl-3-methylindole are surprisingly intermolecularly arylated at the C-2 position by benzene and xylene (22-48% yield) [64, 65]. 

---