Ekaterina A. Filatova

Heterocyclic superbases: retrospective and current trends

The structural principles known to date serving as the basis for the design of heterocyclic compounds with anomalously high basicity (superbasicity) are reviewed. A general classification is given for such superbases as proton sponges, compounds that are similar to proton sponges but are not sponges (proton-sponge-like), and proton traps.

peri-Naphthylenediamines. 31. Study of interconversions of 2,3-dihydroperimidines and 1,8-bis(dialkylamino)naphthalenes. Convenient synthesis of 1,2,2,3-tetramethyl-2,3-dihydroperimidine and a monoisopropyl analog of the “proton sponge”

Efficient procedures were developed for the two-step synthesis of 1,2,2,3-tetramethyl-2,3-dihydroperimidines and for the one-step synthesis of 1,3-dimethyl-2,3-dihydroperimidines starting from 1,8-diaminonaphthalenes. New possibilities of the use of 2,3-dihydroperimidinium salts in the synthesis of 1,8-bis(dialkylamino)naphthalenes (“proton sponges”) containing the N-isopropyl group along with the N-methyl groups were demonstrated. The 1,1,2,2,3-pentamethyl-2,3-dihydroperimidinium cation exists in the acyclic iminium form responsible for its high reactivity.

HETEROCYCLIC ANALOGS OF PLEIADIENE. 67. FORMYLATION OF PERIMIDONES, 2,3-DIHYDROPERIMIDINES, AND PERIMIDINES

Vilsmeier formylation of 1,3-dialkylperimidones, 1,3-dialkyl-2,3-dihydroperimidines, and 2-trifluoromethyl-perimidines is performed. The1H NMR spectra of the resulting mono- and dialdehydes are discussed.

Heterocyclic analogs of pleiadiene. 72. Sulfones of perimidine and 2,3-dihydroperimidine. Synthesis and some properties

The arenesulfonation of perimidines has been carried out in polyphosphoric acid and found to occur at the 6(7) and 4(9) positions. Reduction then gave the first representatives of 2,3-dihydroperimidine sulfones. We report a comparative 1H NMR spectroscopic analysis of the arenesulfonyl- and acylperimidines together with their annular prototropic tautomerism.

Heterocyclic Analogs of Pleiadiene. 68. Unusually Slow (on the NMR Time Scale) Annular Prototropy in the 6(7)-Formyl- and 6(7)-Acetyl-2-trifluoromethylperimidine Series

The case of extremely slow (on the NMR time scale) annular prototropy rare in azole systems has been observed. According to 1H NMR spectral data, both NH tautomers are observed in solutions of 6(7)-formyl- and 6(7)-acetyl-2-trifluoromethylperimidines in CDCl3 and C6D6 at room temperature and even on heating to 60-70°C. The rate of interconversion of the tautomers in DMSO-d6 and CD3CN is sufficiently great that only averaged signals are observed in their 1H NMR spectra. The main reason of the slow tautomerism is the cooperative effect of the 2-CF3 group and the carbonyl substituent which decreases the basicity of the pyridine hetero atom to such an extent that a transfer of a proton between molecules in a nonpolar medium becomes strongly hindered.

peri-Naphthylenediamines: XL. Solvatochromism of 1-methyl-4-[2-(1-naphthyl)ethenyl]pyridinium salts, including that containing “proton sponge” residue

A number of 1-methyl-4-[2-(1-naphthyl)ethenyl]pyridinium salts were synthesized by condensation of 1,4-dimethylpyridinium iodide with naphthalene-1-carbaldehydes containing dimethylamino groups in positions 4 and 5. The obtained salts are characterized by negative solvatochromism which is the most pronounced for those possessing 1,8-bis(dimethylamino)naphthalene (“proton sponge”) and 1,2,2,3-tetramethyl-2,3-dihydroperimidine residues.

Heterocyclic analogs of pleiadiene. 75. Formylation of perimidines and 2,2-dimethyl-2,3-dihydroperimidine under vilsmeier conditions

The formylation of perimidine, its 2-and 3-methyl derivatives, and 2,2-dimethyl-2,3-dihydroperimidine has been studied under the conditions of the Vilsmeier reaction. In the last case recyclization occurs. The characteristics of the 1H NMR spectra of the aldehydes obtained are discussed.

Synthesis of 2-aryl-3-methylbenzo[ g ]indoles from 2-(arylethynyl)-1,8-bis(dimethylamino)naphthalenes: new examples of [1,3]-migration involving N -methyl group

The Sonogashira coupling of 1,8-bis(dimethylamino)-2-iodonaphthalene with 2-nitro-, 4-nitro-, 4-(trifluoromethyl)-, and 4-methoxyphenylacetylenes was used to obtain new 2-(arylethynyl)-1,8-bis(dimethylamino)naphthalenes. Three of the four alkynes, except for the o-nitrophenyl derivative, were isomerized in the presence of palladium and porcelain catalysis to the corresponding 2-aryl-9-(dimethylamino)-1,3-dimethyl-1H-benzo[g]indoles.

Resonance-stabilized α-naphthylmethyl carbocations and spiro compounds based thereon: VII. Transformations of α-naphthylmethyl carbocations stabilized by one electron-donor group or peri-fused heteroring

Abstract1-Hydroxymethyl-and 1-alkoxymethylnaphthalenes containing dimethylamino and methoxy groups or a heteroring in positions 4 and 5 react with protic and Lewis acids to give 1-naphthylmethyl carbocations. Reactions of the latter with the initial alcohol molecule lead to the formation of oligomerization or dehydrogenation (to aldehyde) products or the corresponding dinaphthylmethanes. In some cases, the process was accompanied by cyclodimerization to form cyclohexadienone spiro derivatives in a small yield.