14182-14-0Relevant articles and documents
Ring-opening cyclization of spirocyclopropanes using sulfoxonium ylides
Onuki, Yuta,Nambu, Hisanori,Yakura, Takayuki
, p. 479 - 486 (2020/09/09)
Ring-opening cyclization of cyclohexane-1,3-dione-2-spirocyclopropanes using dimethylsulfoxonium methylide proceeded regioselectively to produce 2,3,4,6,7,8-hexahydro-5H-1-benzopyran-5-ones in good to high yields. The reactions of cycloheptane- and cyclopentane-1,3-dione-2-spirocyclopropanes could construct [7.6]- and [5.6]-fused ring systems. This reaction was also carried out using sulfoxonium ethylide, butylide, and benzylide, resulting in the formation of the corresponding 2,3-trans-disubstituted products in good to high yields, and it was shown that the dimethyl group can act as a dummy substituent. It was found that the 2- and 3-phenyhexahydrobenzopyran-5-ones can be readily converted into 5-hydroxyflavan and 5-hydroxy-isoflavan, respectively.
1,2-Diarylethanols by alternative regioselective reductive ring-opening of 2,3-diaryloxiranes
Blasio, Nadia Di,Lopardo, Maria Teresa,Lupattelli, Paolo
scheme or table, p. 938 - 944 (2009/07/19)
Non-symmetrical ￡rans-2,3-diaryloxiranes have been regioselectively opened by catalytic hydrogenation over Pd/C, NaBH4/Pd and [Cp 2TiCl]/H2O. Although in the catalytic hydrogenation reactions the epoxides were mainly opened at the β-carbon with respect to the substituted aryl ring in all cases, with the [Cp2TiCl]/H 2O system the regioselectivity was affected by the electronic properties of the aryl residues, the epoxides being opened on the carbon bearing the most electron-releasing or the least electron-withdrawing group. With the NaBH4/Pd system different regioisomers were obtained depending on the substituents. Starting from enantioenriched epoxides, no loss of optical purity was observed in the alcohols formed.
Synthesis and reactivity of benzylic sulfonium salts: Benzylation of phenol and thiophenol under near-neutral conditions
Forrester,Jones,Newton,Preston
, p. 2871 - 2884 (2007/10/03)
A series of benzyldimethylsulfonium - and related hydrogensulfate salts have been synthesized from the ternary system ArCH2OH:H2SO4: Me2S or tetrahydrothiophene. The salts are generally stable crystalline solids, but anomalously high reactivity is observed for 9-(anthrylmethyl)dimethylsulfonium hydrogensulfate. Selected sulfonium salts have been used for the O- and S-benzylation of phenol and thiophenol, respectively, in a two phase system under near-neutral conditions. The benzylation of oximes and benzimidazole under basic conditions is also described.
Metalation of o-Halostyrene Oxides. Preparation of Benzocyclobutenols
Akguen, Eyup,Glinski, Margaret B.,Dhawan, Kasturi L.,Durst, Tony
, p. 2730 - 2734 (2007/10/02)
o-Bromo- and o-iodostyrene oxides are converted in fair to good yield to benzocyclobutenols upon treatment with n-BuLi and MgBr2 in THF or ether at -78 deg C, followed by warming to room temperature.The reaction involves initial halogen-lithium exchange followed either by MgBr2-initiated opening of the epoxide function to a haloalkoxide or rearrangement of the epoxide function to a ketone or aldehyde followed by cyclization.Benzocyclobutenol formation was not successful in the case of o-halostilbene oxides.
Process for the purification of epoxy compounds
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, (2008/06/13)
The low molecular water-soluble onium-catalyst dissolved in the liquid mixture of epoxy resin and excess epihalohydrin obtained by the reaction in the presence of base of a compound having --OH, --SH, --COOH or =NH groups with excess 1-halo-2,3-epoxyalkane, is separated therefrom by contacting the liquid mixture, either prior to or after separation therefrom of the precipitated salt produced by the reaction, with at least about 5 parts by weight based on the weight of the catalyst present in the liquid mixture, of an adsorbent containing or capable of absorbing at least 1% by weight of water so strongly that it cannot be removed either by drying over concentrated sulfuric acid or by drying at 110° C. and can only be partially removed by drying at 200° C. under vacuum (about 1 millibar), and then separating the adsorbent with catalyst adsorbed thereon from the liquid mixture.
