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1.
Yevgen Posokhov Alexander Gorski Jens Spanget-Larsen Fritz Duus Poul Erik Hansen Jacek Waluk 《Chemphyschem》2004,5(4):495-502
Thioacetylacetone and its variously deuterated isotopomers have been investigated using electronic and vibrational spectroscopy combined with quantum chemical calculations. Thioacetylacetone is known for its photochromic properties, but the structures of the initial and final forms have been the subject of a long debate. Analysis of the IR spectra recorded in low-temperature argon and xenon matrices, room-temperature solutions, and in the gas phase has allowed us to establish the nature of the photochromic species and of its precursor. Similar to the case of another beta-thioxoketone, monothiodibenzoylmethane, the photo-product has been assigned to the nonchelated SH exo-rotamer of the (Z)-enethiol tautomeric form, whereas the dominant ground-state species corresponds to the chelated (Z)-enol tautomeric form. Detailed vibrational assignments have been proposed for both forms based on quantum chemical calculations and polarization experiments. In the case of the chelated (Z)-enol species prevailing in the ground state, a second-order perturbative anharmonic analysis at the B3LYP/cc-pVTZ level indicated strong anharmonic effects associated with the intramolecular hydrogen bond, leading to a shift of more than 600 cm-1 of the wavenumber of the OH-stretching vibration. A small fraction of the SH endo-rotameric chelated (Z)-enethiol form was also detected under unperturbed conditions. The (Z)-enethiol form can be converted into the (Z)-enol form by irradiation at 290 nm. 相似文献
2.
Jun TakayamaSeiko Fukuda Yoshiaki SugiharaAkihiko Ishii Juzo Nakayama 《Tetrahedron letters》2003,44(28):5159-5162
Hetero Diels-Alder reactions of 3,4-di-tert-butylthiophene 1-oxide (1) with thioaldehydes and thioketones take place exclusively, except the reaction with thiobenzophenone, at the syn-π-face of 1 with respect to the SO bond. The π-face selectivity was explained in terms of the extent of conformational changes of 1 that are brought about in the process to the transition states. 相似文献
3.
Dr. Ramachandran Azhakar Dr. Rajendra S. Ghadwal Prof. Dr. Herbert W. Roesky Prof. Dr. Ricardo A. Mata Hilke Wolf Regine Herbst‐Irmer Prof. Dr. Dietmar Stalke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(11):3715-3720
Three‐ and five‐membered rings that bear the (Si‐C‐S ) and (Si‐C‐C‐C‐S ) unit have been synthesized by the reactions of L SiCl ( 1 ; L =PhC(NtBu)2) and L′ Si ( 2 ; L′ =CH{(C?CH2)(CMe)(2,6‐iPr2C6H3N)2}) with the thioketone 4,4′‐bis(dimethylamino)thiobenzophenone. Treatment of 4,4′‐bis(dimethylamino)thiobenzophenone with L SiCl at room temperature furnished the [1+2]‐cycloaddition product silathiacyclopropane 3 . However, reaction of 4,4′‐bis(dimethylamino)thiobenzophenone with L′ Si at low temperature afforded a [1+4]‐cycloaddition to yield the five‐membered ring product 4 . Compounds 3 and 4 were characterized by NMR spectroscopy, EIMS, and elemental analysis. The molecular structures of 3 and 4 were unambiguously established by single‐crystal X‐ray structural analysis. The room‐temperature reaction of 4,4′‐bis(dimethylamino)thiobenzophenone with L′ Si resulted in products 4 and 5 , in which 4 is the dearomatized product and 5 is formed under the 1,3‐migration of a hydrogen atom from the aromatic phenyl ring to the carbon atom of the C? S unit. Furthermore, the optimized structures of probable products were investigated by using DFT calculations. 相似文献
4.
Reactions of Cycloaliphatic Thioketones and Their Oxo Analogues with Lithiated Methoxyallene: A New Approach to Vinylthiiranes 下载免费PDF全文
Dr. Marcin Jasiński Prof. Grzegorz Mlostoń Michał Stolarski Wilhelmine Costa Dr. Moises Domínguez Prof. Hans‐Ulrich Reissig 《化学:亚洲杂志》2014,9(9):2641-2648
Admantanethione smoothly reacted with lithiated methoxyallene at low temperatures yielding the expected allenyl‐substituted thiolate, which upon aqueous work‐up underwent spontaneous 1,3‐cyclization to afford a hitherto unknown methoxy‐substituted vinylthiirane derivative. The analogous reaction with adamantanone led to the corresponding allenyl alcohol that can be isolated and—depending on the conditions applied—either be converted into the corresponding vinyloxirane or into the 2,5‐dihydrofuran derivative. Sterically more crowded thioketones were also combined with lithiated methoxyallene, but in these cases competitive 1,5‐cyclization leading to isomeric dihydrothiophene derivatives was observed. DFT calculations of model intermediates and products show distinct energy differences of the sulfur and the corresponding oxygen compounds. Desulfurization of the adamantanethione‐derived vinylthiirane yielded a methoxy‐substituted 1,3‐diene that was studied in cycloadditions with electron‐deficient dienophiles. Whereas in the case of tetracyanoethylene the corresponding cyclobutane derivative was formed, the reaction with nitrosobenzene provided the expected 1,2‐oxazine derivative. By reductive cleavage of the N? O bond this heterocycle was converted into an unsaturated amino alcohol bearing an adamantane moiety. 相似文献
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6.
The molecular mechanisms of addition of dihalocarbenes and dimethoxycarbene to thioketones derived from 2,2,4,4-tetrmethylcyclobutane-1,3-dione were examined on the basis of the DFT wb97xd/6-311g(d,p)(PCM) calculations. Obtained results demonstrated that the examined processes exhibit polar nature and in the case of electrophilic dichloro-, and dibromocarbenes are initiated by the attack of carbene species onto the sulfur atom of the C=S group. Remarkably, reactions involving more electrophilic carbenes (dichloro-, and dibromocarbene) proceeds via stepwise mechanism involving thiocarbonyl ylide as a transient intermediate. In contrast, analogous reactions with nucleophilic dimethoxycarbene occur via a single step reaction, which can be considered as the [2 + 1] cycloaddition reaction initiated by the attack onto the C=S bond. A computational study showed that difluorocarbene tends to react as a nucleophilic species and resembles rather dimethoxycarbene and not typical dihalocarbene species. Significantly higher reactivity of the thioketone unit in comparison to the ketone group, both present in 3-thioxo-2,2,4,4-tetramthylcyclobutanone molecule, was rationalized in the light of DFT computational study. 相似文献
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Grzegorz Mlosto Katarzyna Urbaniak Malwina Sobiecka Heinz Heimgartner Ernst-Ulrich Würthwein Reinhold Zimmer Dieter Lentz Hans-Ulrich Reissig 《Molecules (Basel, Switzerland)》2021,26(9)
The hetero-Diels-Alder reactions of in situ-generated azoalkenes with thioketones were shown to offer a straightforward method for an efficient and regioselective synthesis of scarcely known N-substituted 1,3,4-thiadiazine derivatives. The scope of the method was fairly broad, allowing the use of a series of aryl-, ferrocenyl-, and alkyl-substituted thioketones. However, in the case of N-tosyl-substituted cycloadducts derived from 1-thioxo-2,2,4,4-tetramethylcyclobutan-3-one and the structurally analogous 1,3-dithione, a more complicated pathway was observed. By elimination of toluene sulfinic acid, the initially formed cycloadducts afforded 2H-1,3,4-thiadiazines as final products. Advanced DFT calculations revealed that the observed high regioselectivity was due to kinetic reaction control and that the (4 + 2)-cycloadditions of sterically less unhindered thiones occurred via highly unsymmetric transition states with shorter C..S-distances (2.27–2.58 Å) and longer N..C-distances (3.02–3.57 Å). In the extreme case of the sterically very hindered 2,2,4,4-tetramethylcyclobutan-1,3-dione-derived thioketones, a zwitterionic intermediate with a fully formed C‒S bond was detected, which underwent ring closure to the 1,3,4-thiadiazine derivative in a second step. For the hypothetical formation of the regioisomeric 1,2,3-thiadiazine derivatives, the DFT calculations proposed more symmetric transition states with considerably higher energies. 相似文献
9.
《Mendeleev Communications》2022,32(3):384-385
The reaction distyryl thioketone with donor alkenes (norbornene and styrene) gives adducts of the hetero-Diels–Alder reaction. In the case of maleic acid derivatives, a tandem reaction occurs which leads to polycyclic derivatives of 3,4-dihydro-2H-thiopyran. The stereochemical features of the ongoing transformations were examined. 相似文献
10.
《Analytical letters》2012,45(1):105-111
Abstract A spectrophotometric-kinetic method is proposed for the assay of thioketones. The method is based on the catalysis of the sodium azide-iodine-starch reaction by thiourea at concentrations from 10 to 100 ppb. The course of the reaction is monitored spectrophotometrically by the reduction of iodine to iodide using starch iodine indicator. 相似文献