Yu. M. Chunaev

Reaction of the Fischer base with 8-hydroxy-1-naphthaldehydes. Investigation of the reaction products by 13C NMR spectroscopy

The product of the condensation of the Fischer base with unsubstituted 8-hydroxy-1-naphthaldehyde is a bisindolinespirooxepine. 5,7-Dinitro-8-hydroxy-1-naphthaldehyde reacts with the Fischer base to give a merocyanine that does not display a tendency to undergo conversion to the cyclic form. 2H-Naphtho[1,8-bc]furan derivatives are formed in the reaction of the Fischer base with 5-nitro-, 5-bromo-, and 5,7-dibromo-8-hydroxy-1-naphthaldehydes. The structures of the compounds obtained were established on the basis of data from the PMR and 13C NMR spectra. It was shown by means of the 13C NMR spectra that the product of the condensation of phthalic monoaldehyde with the Fischer base is not a seven-membered spirolactone, as previously assumed, but rather a phthalide derivative.

Influence of substituents in salicylaldehyde molecule on interaction with 2-imino-3,5-dimethylthiazolidine

Salicylaldehyde, 5-chlorosalicylaldehyde, or o-vanillin will react with 2-imino-3,5-dimethylthiazolidine to form previously unknown bis(3,5-dimethylthiazolidin-2-ylideneamino)-2-hydroxyphenylmethanes. If strong electron-acceptor groups are present on the aromatic ring, an acid-base interaction takes place. Thus, 3-nitro-5-methoxy-, 3-nitro-5-chloro-, and 3-bromo-5-nitrosalicylaldehyde react with the heterocyclic base to form saltlike complexes, the structure of which has been confirmed by x-ray diffraction.

STRUCTURE OF 2-AMINO-5-METHYLTHIAZOLINE AND ITS N-METHYL DERIVATIVES

As indicated by PMR spectroscopic data, 2-amino-5-methylthiazoline and 2-methylamino-5-methylthiazoline exist in the imine form in the temperature interval from +20° to −100° C. Interaction of the 2-amino-5-methylthiazoline with methyl iodide results in alkylation at the endocyclic nitrogen atom.

Synthesis and photochemical properties of the indoline series fulgides

Using the Stobbe condensation fulgides that undergo E, Z-isomerization on exposure to UV radiation are obtained from diethyl [2-(1,3,3-trimethyindoline-2-ilidene)ethylidene]succinate, and benzaldehyde and its derivatives; and from 1,2-dimethyl-3-formylindole and ω-formyl-1,3,3-trimethyl-2-methyleneindoline. The structure and photochemical changes of the fulgides were investigated by means of PMR.

Mechanism of the photoreactions of fulgides based on 1,2-dimethyl-3-formylindole

Only E ⇄ Z isomerization is observed for the steady irradiation of fulgides based on 1,2-dimethyl-3-formylindole in contrast to the analogs based on 3-acetylindole. The formation of cyclic photoisomers is registered by the method of impulse photolysis. The presence of a methyl substituent in the position 2 of the indole portion leads to a significant increase in the stability of the photochromic system. The introduction of alternative reaction centers of cyclization in the form of bulky phenyl groups leads to the suppression of electrocyclization at the position 2 of the indole portion and the formation of dihydronaphthalene structures.

Photochromic fulgides based on 1-methyl-2-formylindole

The reactions of 1-methyl-2-formylindole with the diethyl esters of alkyl- and phenylmethylene-substituted itaconic acids led to the production of photochromic fulgides, which formed deeply colored 5,8b-dihydrocarbazole derivatives during UV irradiation. It was found by PMR that the fulgides also undergo E,Z isomerization during UV irradiation.

Heterocyclic fulgides based on 1,2-dimethyl-3-formylindole

Nonphotochromic fulgides of the indole series, which undergo E, Z isomerization under UV irradiation, were obtained from 1,2-dimethyl-3-formylindole and esters of aryl- and alkylmethylene-substituted itaconic acids by Stobbe condensation in the presence of strong bases.

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.

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

The Fischer base reacts with α-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.

Reaction of Fischer's base with o-hydroxycinnamaldehydes

On the basis of a study of the PMR spectra and alternative synthesis it was established that the “dicondensed” products of the reaction of Fischers base with o-hydroxycinnamaldehydes are not oxocine derivatives, as was previously assumed, but rather are bisindoline spirochromans that are identical to the products of the reaction of vinylogs of Fischers base with salicylaldehydes.