Yu. A. Sayapin

New method for the synthesis of β-tropolones : Structures of condensation products of o-quinones with 2-methylquinolines and the mechanism of their formation

A new method was developed for the synthesis of functionalized β-tropolones based on acid-catalyzed condensation of 2-methylquinoline derivatives with 3,5-di(tert-butyl)-1,2-benzoquinone and 4,6-di(tert-butyl)-3-nitro-1,2-benzoquinone (14). The mechanism of the multistep reaction giving rise to β-tropolones and their tautomerism were studied by quantum chemical methods (DFT B3LYP/6-31G**). The reaction of 2-methylquinoline derivatives containing the tertiary amino group at position 4 with quinone 14 is accompanied by the formation of derivatives of a new heterocyclic system, viz., 4,6-dioxo-2-azabicyclo[3.3.0]octa-2,7-diene N-oxide. The molecular and crystal structures of two 5,7-di(tert-butyl)-3-hydroxy-2-(quinolin-2-yl)tropolones and two dioxoazabicyclooctadiene N-oxides, as well as of the preparatively isolated intermediate of the first condensation step and of the by-product of the reaction were established by X-ray diffraction.

3,5-Di-tert-butyl-1,2-benzoquinone in the synthesis of quinolino[4,5-bc][1,5]benzoxazepines, aminophenols, and phenoxazines

Reaction of 3,5-di-tert-butyl-1,2-benzoquinone with 5-amino-4-chloroquinolines gave derivatives of a new fused heterocyclic system, substituted quinolino[4,5-bc][1,5]benzoxazepines. The molecular structure of 9,11-di-tert-butyl-2,4,6-trimethyl-7H-quinolino[4,5-bc][1,5]benzoxazepine was determined by X-ray analysis. 3,5-Di-tert-butyl-1,2-benzoquinone reacted with o-nitro-, o-acyl-, and o-methoxycarbonylanilines and some amino-substituted nitrogen-containing heterocycles to form the corresponding sterically hindered N-aryl-(hetaryl)-o-aminophenols. Di-tert-butyl-substituted phenoxazines were obtained as a result of thermal cyclization of intermediately formed quinone imines.

Synthesis and structure of heterocyclic derivatives of pyran-2-ones based on the dimer of 4,6-di(tert-butyl)-3-hydroxy-1,2-benzoquinone

Acid-catalyzed reaction of 6,10a-dihydroxy-3,4a,7,9-tetra(tert-butyl)-1,2,4a,10a-tetrahydrodibenzo-[b,e][1,4]dioxine-1,2-dione with 2-methylquinoline derivatives led to the formation of a previously unknown system 6-[(Z)-2-(quinolin-2-yl)-1-hydroxyethen-1-yl]pyran-2-one. The molecular structure of 3,5-di(tert-butyl)-6-[(Z)-2-(7,8-dimethyl-4-chloroquinolin-2-yl)-1-hydroxyvinyl]pyran-2-one was established by XRD method; the energy and structural characteristics of its isomers in the gas phase and in a polar solvent were calculated by quantumchemical methods (B3LYP/6-31G**).

Synthesis and structure of 2,2′-spirobi(1,3-benzodioxole) derivative prepared from 3,5-di(tert-butyl)-1,2-benzoquinone

Abstract3,5-Di(tert-butyl)-1,2-benzoquinone reacted with 1,2,3-trimethylbenzimidazolium iodide led to the formation of 2,2′-spirobi[4,6-di(tert-butyl)-1,3-benzodioxole]. The reaction mechanism was suggested. The structure of 2,2′-spirobi[4,6-di(tert-butyl)-1,3-benzodioxole] was established by means of X-ray diffraction analysis.

Synthesis and structure of new 2-(2-quinolyl)-1,3-tropolone derivatives

Abstract4,6-Di-tert-butyl-3-nitro-1,2-benzoquinone reacts with substituted 2-methylquinolines to give the corresponding 2-(2-quinolyl)-4-nitro-1,3-tropolones and 2-(2-quinolyl)-1,3-tropolones.

Structure of the oxidative dimerization product of 4,6-di(tert-butyl)pyrogallol

The structure of the oxidation product of 4,6-di(tert-butyl)pyrogallol, viz., 6,10a-dihydroxy-3,4a, 7,9-tetra(tert-butyl)-1,2,4a,10a-tetrahydrodibenzo[b,e][1,4]dioxine-1,2-dione, was established by X-ray diffraction. Dimerization of intermediate 3-hydroxy-4,6-di(tert-butyl)-1,2-benzoquinone occurs by the mechanism of Diels—Alder heterocyclization.

NEW PHOTOCHROMIC BISPIROPYRAN

The photochromic properties of spiropyrans are a function not only of the contribution of the hetarene fragment but also, to a greater extent, to the substituents in the 2H-chromene part of the molecule [1]. We have obtained a new spiropyran 1, which is a unique salicylaldehyde analog, and used this compound to synthesize spiropyran 2, containing two different spirocyclic sites and, thus, two asymmetric carbon atoms.

Synthesis and structure of 4,6-di(tert-butyl)-2-(4-chloro-7,8-dimethylquinolin-2-yl)-7-(piperidin-1-ylmethyl)-1,3-tropolone

The reaction of 4-chloro-2,7,8-trimethylquinoline with 4,6-di(tert-butyl)-3-(piperidin- 1-ylmethyl)-1,2-benzoquinone, which was prepared by the in situ oxidation of 4,6-di(tert- butyl)-3-(piperidin-1-ylmethyl)pyrocatechol with sodium nitrite, gave 4,6-di(tert-butyl)-2- (4-chloro-7,8-dimethylquinolin-2-yl)-7-(piperidin-1-ylmethyl)-1,3-tropolone. Its structure was determined by X-ray diffraction. The energy and structural characteristics of the tauto- mers of this compound in the gas phase and in a polar solution were calculated by quantum chemical methods (PBE0/6-311+G(d,p)).

The structure of side product in the synthesis of substituted 1,3-tropolones

The structure of pyrocatechol p-toluenesulfonate resulting from the reaction between 3,5-di(tert-butyl)-1,2-benzoquinone and substituted 2-methylquinolines was proved by X-ray diffraction analysis.