A number of tetracyclic compounds with annulated nitrosulfolane and pyranochromenone rings were synthesized by reacting 2-benzylidene-3-methyl-4-nitro-2,5-dihydrothiophene 1,1-dioxides with ...4-hydroxycoumarin. Structural features of the resulting polycyclic compounds were established on the basis of IR,
1
Н,
13
С NMR,
1
Н–
13
С HMQC,
1
Н–
13
С HMBC, NOESY spectroscopy and X-ray structural analysis data.
The reactions of thiophene- and
N
-benzylindole-containing
gem
-acetylnitroethenes with 2-aminobenzothiol lead to the formation of 4-methyl-3-nitro-2,3-dihydro-1,5-benzothiazepines. At the same time, ...only
S
-adducts were formed in the reactions of
gem
benzoylnitroethenes containing a thiophene, furan, or
N
-benzylindole substituent with 2-aminobenzothiol.
1-Aminoacyloxygermatran containing a hexacoordinated germanium atom and an amino acid substituent in its structure—L-valine—was synthesized and studied by high resolution
1
H and
13
C NMR ...spectroscopy for the first time. Complete signal assignment in two different parts of
1
H spectra containing 8 and 12 overlapped multiplets from –O-CH
2
- and –N-CH
2
- protons was made by using homonuclear
J
-COSY, COSY and NOESY methods and on base data of heteronuclear HMQC and HMBC experiments. The spatial structure of the studied 1-aminoacyloxygermatran was proved on the basis of data on interproton through-space interactions obtained from the NOESY spectra at different mixing times from 0.3 to 1.2 s. Simultaneously, along with cross peaks from positive NOEs, exchange cross peaks between germinal protons of different -O-CH
2
- groups were found in the same spectra, thus indicating the existence of a slow (in the NMR time scale) dynamic process in this compound associated with rearrangements within the atranium cycle.
The synthesis of previously unknown 4,5-dimethylfuro3,4-dpyridazin-1(2H)-one has been proposed and structurally characterized via a single-crystal X-ray diffraction analysis, 1H, 13C–{1H}, 1H–13C ...HMQC, and 1H–13C HMBC NMR spectroscopy, and IR spectroscopy.
The interactions of alkyl 3-bromo-3-nitroacrylates with 1,2-diaminoethane, 1,2-diaminopropane, 1,2-diaminocyclohexane, and 2-aminoethanol were shown to provide a convenient route for the synthesis of ...six-membered heterocycles – (3
Z
)-3-(nitromethylidene)-piperazin-2-ones and (3
Z
)-3-(nitromethylidene)morpholin-2-one. The structures of the synthesized heterocycles were characterized by a range of spectral methods and by X-ray structural analysis.
NMR spectroscopy methods have been used to prove structures of two diastereomers of cyclopropa
a
pyrrolizine spiro-fused with a benzo4,5imidazo1,2-
a
indole fragment which were obtained through a ...three-component 1,3-dipolar cycloaddition reaction and isolated in a ratio of 6:1. Complete signal assignment in
1
H and
13
C spectra of each compound was made by using some homonuclear (COSY, NOESY) and heteronuclear (HMQC, HMBC) NMR experiments. The spatial structure of the studied diastereomers was proved on the basis of data on interproton through-space interactions obtained from the NOESY spectra at a mixing time of 0.5 s. The comparison of the experimental and calculated values of the vicinal constants and interproton distances indicates that each of the studied diastereomers in solution is characterized by a fast (in the NMR time scale) conformational equilibrium due to the inversion of the nitrogen atom in the cyclopropa
a
pyrrolizine fragment.
The reaction of acetyl-containing furan-3-carboxylates with substituted hydrazines in an alcohol solution leads to the formation of substituted furan-3-carboxylate hydrazones. The resulting ...hydrazones have
E
-configuration, as determined by NMR spectroscopy and X-ray diffraction analysis.
The reactions of 2-benzylidene-3-methyl-4-nitro-2,5-dihydrothiophene 1,1-dioxides with dimedone were used to synthesize a series of tricyclic compounds containing fused nitrosulfolane and ...octahydrochromenone rings. The structural features of the obtained polycyclic compounds were established on the basis of IR and NMR spectra, as well as X-ray structural analysis.
The reactions of alkyl 3-bromo-3-nitroacrylates with N,N-, N,O-, and О,О-
o-
phenylene bisnucleophiles resulted in the formation of benzo-fused heterocycles: reactions with
о
-phenylenediamines and
о
...-aminophenols gave six-membered N,N- and N,O-heterocycles – (
Z
)-3-nitromethylidene-3,4-dihydroquinoxalin-2(1
Н
)-ones and (
Z
)-3-nitromethylidene-3,4-dihydro-2
Н
-1,4-benzoxazin-2-ones, while the use of pyrocatechols led to the formation of a five-membered O,O-heterocyclic system, providing alkyl 2-(nitromethyl)-1,3-benzodioxole-2-carboxylates. The nitroenamine moiety of the obtained six-membered heterocycles was shown to undergo tautomeric transformations.
A convenient diastereoselective method for the preparation of methyl (2
R*
,3
R*
)-3-aryl(pyridyl)-5-oxopyrrolidine-2-carboxylates was developed on the basis of the neutralization reaction of ...diastereohomogeneous dimethyl (2
R*
,3
R*
)-3-aryl(pyridyl)glutamate hydrochlorides.
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