Reaction of the fischer base with nitro- and bromo-substituted o-hydroxycinnamaldehydes

The Fischer base reacts with -ethyl-5-nitro-, 5-bromo-, and 3,5-dibromo-2-hydroxy-cinnamaldehydes to give bisindoline spirochromans, with 3-bromo-5-nitro-2-hydroxy-cinnamaldehyde to give a mixture of a spirochroman and a monoindoline merocyanine, and with 3,5-dinitro-2-hydroxycinnamaldehyde to give only a merocyanine. The monoindoline merocyanines obtained do not display a tendency to undergo intramolecular cyclization to give spiro-2H-oxocines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 775–778, June, 1984.     

New Reactions of Ortho Esters

Russian Journal of Organic Chemistry - A new reaction of triethyl orthoformate with ethyl butyrate has been revealed. It afforded diethoxymethyl butanoate and its hydrated form,...     

Pyrroloindoles. 2. Some electrophilic substitution reactions in the 1H, 6H-pyrrolo[2, 3-e] indole series

As expected, the 3 and 8 positions are the reaction centers of 1H, 6H-pyrrolo-[2, 3-e] indole in the Vilsmeier-Haack and Mannich reactions. Diazo coupling takes place primarily in the 3 position and leads primarily to monosubstitution products. 6,8-Diacetyl-1H,6H-pyrrolo [2,3-e]indole and 1,8-diacetyl-1H, 6H-pyrrolo-[2,3-e] indole were isolated from the acetylation products.See [1] for communication 1.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 639–644, May, 1980.     

Bisindoles. 25. Properties of 3h,8h-indolo[4,5-e]- and -[5,4-e]indole

Electrophilic-substitution reactions for 3H,8H-indolo[4,5-e]- and -[5,4-e]indole were studied. Mono- and disubstituted compounds were isolated as a result of formylation and acetylation, whereas only monosubstitution products were isolated in the case if diazo coupling. It is shown that in the dimethylaminomethylation of 3H,8H-indolo[4,5-e]indole steric factors hinder the formation of a disubstituted compound, while the formation of \-substitution products is hindered in the case of diazo coupling of 3H,8H-indolo[4,5-e]- and-[5,4-e]indole.See [1] for Communication 24.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1205–1212, September, 1988.     

Pyrroloindoles. 8. Electrophilic substitution in the 1H,5H-pyrrolo[2,3-f]indole and 3H,6H-pyrrolo[3,2-e]indole series

The principles of the electron density distribution in 1H,5H-pyrrolo [2,3-f]indole and 3H,6H-pyrrolo[3,2-e]indole molecules were determined on the basis of quantumchemical calculations. These results were confirmed by the results of the investigated electrophilic-substitution reactions. The reaction centers of these compounds proved to be the same positions as in indole, viz., the 3 and 7 and 1 and 8 positions, respectively. The impossibility of 1,8-disubstitution in the angular heteroring was demonstrated in the case of bulky substituents; this was explained by a steric effect.See [1] for communication 7.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1086–1091, August, 1983.     

Intramolecular cyclization of 2-hydroxycinnamaldehydes

The effect of substituents on the intramolecular cyclization of 2-hydroxycinnamaldehydes was studied. It was established that aldehydes that contain bulky groups in the side chain and in the 3 position of the benzene ring are readily converted to intramolecular hemiacetals or bimolecular acetals either spontaneously at the moment of isolation or in solutions in DMF or DMSO, as well as on heating. An increase in the lability of the phenolic proton favors the cyclization.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 460–465, April, 1988.     

Dual reactivity of an intermediate cation formed in the photolysis of dihydroquinolines in methanol

Photolysis of 2,2,4,6-tetramethyl- (1) and 1,2,2,4,6-pentamethyl-1,2-dihydroquinoline (2) in methanolic alkali yields only 4-methoxy-2,2,4,6-tetramethyl-1,2,3,4-tetrahydroquinoline in the former case and a mixture of 4-methoxy- and 4-hydroxy-1,2,2,4,6-pentamethyl-1,2,3,4-tetrahydroquinoline in the latter case. This result was rationalized by the existence of two resonance structures of an intermediate cation, viz., carbocationic and ortho-quinomethaneiminium species. The cation from 1 reacts with an alkali in the ortho-quinomethaneiminium form, and the cation generated from 2 reacts in the carbocationic form.     

Indole derivatives. 131. The basicity of 5- and 6-aminoindoles

The pK_a values for the 5- and 6-aminoindoles were determined from potentiometric titration curves and from ¹³C NMR data on the total change of the chemical shifts of the carbon atom signals on protonation of the amino group. The pK_a values obtained (5.99 and 5.53) were higher than those of aniline (3.92) or -naphthylamine (3.39).For Communication 130, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, 766–769, June, 1988.