53117-13-8Relevant academic research and scientific papers
Formation of Tetrahydrothiophenes via a Thia-Paternò-Büchi-Initiated Domino Photochemical Reaction
Kassir, Ahmad F.,Guillot, Régis,Scherrmann, Marie-Christine,Boddaert, Thomas,Aitken, David J.
supporting information, p. 8522 - 8527 (2020/11/12)
We have established photochemical access to thietane or tetrahydrothiophene compounds from thiobenzophenone derivatives and acrylonitrile, wherein the product selectivity is controlled by a simple adjustment of the reagent concentration in solution. Small libraries of five-membered ring sulfur-containing compounds were prepared through a thia-Paternò-Büchi reaction, followed by a previously unknown regioselective photochemical ring enlargement reaction in a domino process or a stepwise fashion. A mechanism is proposed to rationalize this ring enlargement reaction via a carbene species provided from photoexcited thiocarbonyl compounds.
Synthesis method of 4,4-difluorobenzophenone serving as intermediate of flunarizine medicine
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Paragraph 0014; 0015, (2016/12/07)
A synthesis method of 4,4-difluorobenzophenone serving as an intermediate of a flunarizine medicine comprises steps as follows: 0.21-0.23 mol of cuprous bromide and 200 ml of carbon disulfide are added to a reaction container provided with a stirrer, a thermometer, a reflux condenser and a dropping funnel, the stirring speed is controlled to be 130-160 rpm, the temperature of a solution is reduced to 7-9 DEG C, 0.21 mol of fluobenzene (2) is dropwise added, then the solution is heated to reach 35-40 DEG C and stirred for 4-5 h until no gas is generated, the solution is left to stand for 30-32 h, the intermediate (3) is generated, 120-150 ml of a salt solution is added, carbon disulfide which does not react is evaporated, a little water is added, distillation under reduced pressure is performed until no oily matters are distilled, an organic layer is separated, a water layer is extracted 5-8 times with a nitromethane solution, organic layers are combined, dehydration is performed through an activated aluminum oxide, the temperature of the solution is reduced to 3-6 DEG C, crystals are separated out, and white flaky 4,4-difluorobenzophenone crystals are obtained after filtering and drying, wherein the mass fraction of carbon disulfide is 95%-98%.
Stereochemistry of the [4 + 2] cycloaddition of diarylselenoketones with conjugated dienes
Wilker, Stefanie,Erker, Gerhard
, p. 10922 - 10930 (2007/10/03)
The ylides Ph3P=CAr1Ar2 1a-g (Ar = C6H5, p-C6H4Cl, p-C6H4F, m-C6H4CF3, p-C6H4OCH3, p-C6H4-CH3) were treated with elemental selenium (～80°C) to give the corresponding selenoketones Se=CAr1Ar2 2 by Staudinger-chalcogenation. Their reaction with trans,trans-2,4-hexadiene proceeds completely stereospecifically to yield the 2,2-diaryl-3,6-dihydro-cis-3,6-dimethyl-2H-selenapyrans 3. In contrast, the reactions of the selenoketones 2 with cis,trans-2,4-hexadiene proceeds stereoselectively, also giving the dihydro-cis-dimethyl-2H-selenapyrans 3 as the major products, now admixed with small amounts of the dihydro-trans-dimethyl-2H-selenapyran isomers 4. The [4 + 2] cycloaddition of 2 with cis,trans-2,4-hexadiene proceeds stereospecifically, however, when carried out at a pressure of 12 kbar, now yielding 4 as the major products along with the corresponding tetraarylethenes 8. Along with the results of additional mechanistic studies (determination of solvent and substituent effects) it can be concluded that diarylselenoketones are likely to react by means of a concerted [4 + 2] cycloaddition with very reactive conjugated dienes (such as trans,trans-2,4-hexadiene), whereas a stepwise mechanism, resulting in diene cis/trans-isomerization with subsequent mechanistic "leakage" to the concerted pathway, appears to be preferred when a much less reactive conjugated diene such as cis,trans-2,4-hexadiene is employed. The reaction of the corresponding diarylthioketones 5a-g with trans,trans- and cis,trans-2,4-hexadiene, respectively, shows an analogous behavior.
