Synthesis of Nonracemic 9-(1-Methoxycarbonylethyl)-1,2,3,4-tetrahydrocarbazole

A new approach has been proposed to the synthesis of indole derivatives containing a chiral substituent at the nitrogen atom, comprizing Fischer indolization of phenylhydrazines with a chiral substituent at the -nitrogen atom. The initial hydrazines were obtained by the alkylation (Mitsunobu reaction applying optically active esters of lactic acid) of anilines containing an electron-accepting substituent at the amino group. Subsequent removal of the activating acceptor grouping was realized by nitrosation of the chiral secondary aniline followed by reduction of the corresponding N-nitroso compound.     

Interaction of (1-phenylethyl)indole-2-carbonitrile with C-nucleophiles

Methods of obtaining ketones and enamino esters have been developed on the basis of reactions of 1-(1-phenylethyl)indole-2-carbonitrile with organomagnesium and organozinc compounds. Removal of a benzyl group from the indole nitrogen atom by the Grignard reagent has been discovered. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1179–1183, August, 2006.     

Catalyst-Free Arylation of Tertiary Phosphines with Diaryliodonium Salts Enabled by Visible Light

The visible-light-induced arylation of tertiary phosphines with aryl(mesityl)iodonium triflates to produce the quaternary phosphonium salts occurs under mild, metal, and catalyst-free conditions. Photo-excited EDA complexes between diaryliodonium salts and phosphines supposedly enable this transformation, which is difficult to achieve through the traditional ground-state reactions. Demonstrating high functional group tolerance, broad scope, and complete selectivity of the aryl group transfer, the method is particularly compatible with sterically congested phosphines, which are challenging under metal-based catalytic methods.     

Synthesis of indoles from pyridinium compounds 10. Influence of solvents on process of indolization of 3-intropyridinium cations by the action of the N-methylimine of methyl ethyl ketone

A study has been made of the influence of solvents on the process of indolization of the methiodide of sym-3-nitrocollidine by the action of the N-methylimine of methyl ethyl ketone. An inversely proportional relationship has been found between the content of the 3,7-unsubstituted indole in the indole fractions and the donor strength of the solvent.For Communication 9, See [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, 1187–1190, September 1992.     

Synthesis of Derivatives of 2-(Indol-1-yl)propionic Acids

We have developed a method for synthesis of N-substituted derivatives of indole from N-phenylalanine, including Fischer cyclization of the corresponding arylalkylhydrazones. The starting hydrazines were obtained by reduction of the corresponding nitrosamines. We have established that the optimum reduction method is to use metallic zinc in a methanol-hydrochloric acid system at low temperatures.     

On the Absolute Convergence of Fourier Series

The necessary and sufficient conditions of the absolute convergence of a trigonometric Fourier series are established for continuous 2-periodic functions which in [0, 2] have a finite number of intervals of convexity, and whose nth Fourier coefficients are O((l/n; f)/n), where ( f) is the continuity modulus of the function f.     

Determination of the ultra long range spin-spin coupling constants using overall line shape analysis in the1H NMR spectra of fullerene-C60 cycloadducts with 1-(4-nitrophenyl)-3-phenylnitrile ylide

On the basis of the overall signal line shape in the¹H NMR spectra of [6,6]-closed and [5,6]-open fullerene-C₆₀ cycloadducts with 1-(4-nitrophenyl)-3-phenylnitrile ylide we determined the values of the long range spin-spin coupling for the aliphatic proton of the heterocyclic fragment with the aromatic protons.M. V. Lomonosov State University, Moscow 119899, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1500–1505, November, 1999.     

Stereoselectivity in the reduction of chiral indoles to indolines

The reduction of 2-alkylindoles containing a chiral substituent at the nitrogen atom by sodium cyanoborohydride in an acidic medium at -80°C is accompanied by the formation of indolines with S-configuration of the new chiral site at C(₂). An AMI quantum chemical calculation showed that the major diastereomer has greater thermodynamic stability. However, the high diastereoselectivity of this reduction may be attributed only to the relative stability of the different conformations of the intermediate indoleninium cations leading to different diastereomers.M. V. Lomonosov Moscow State University, 119899 Moscow Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1199–1208, September, 1996. Original article submitted August 30, 1996.     

2- and 3-phenylsulfonylindoles – synthetic equivalents of unsubstituted indole in N-alkylation reactions

The N-alkylation of 2- and 3-phenylsulfonylindoles under various conditions and the subsequent removal of the activating phenylsulfonyl group by reductive desulfonylation using Raney nickel leads to N-alkylindoles in high yield. 2-Phenylsulfonylindole readily undergoes the Mitsunobu reaction, while isomeric 3-phenylsulfonylindole is relatively inert under these conditions.