- How Reaction Conditions May Influence the Regioselectivity in the Synthesis of 2,3-Dihydro-1,4-benzoxathiine Derivatives
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The exploration of different reaction conditions aiming to obtain both 2,3-dihydro-1,4-benzoxathiine-2-yl derivatives and 2,3-dihydro-1,4-benzoxathiine-3-yl ones is reported. The treatment of 1,2-mercaptophenol with an organic base and a specific 2-bromo acrylate results in a solvent- and substrate-dependent exclusive solvation of O- and S-anions, thus managing the regioselectivity.
- Casiraghi, Andrea,Valoti, Ermanno,Suigo, Lorenzo,Artasensi, Angelica,Sorvillo, Erica,Straniero, Valentina
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p. 13217 - 13227
(2018/10/24)
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- Robust eco-friendly protocol for the preparation of γ-hydroxy- α,β-acetylenic esters by sequential one-pot elimination-addition of 2-bromoacrylates to aldehydes promoted by LTMP in 2-MeTHF
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An efficient and widely applicable preparation of γ-hydroxy-α, β-acetylenic esters is described by means of a one-pot dehydrobromination of a 2-bromoacrylate ester with LTMP followed by the electrophilic addition of the transient propiolate to different aldehydes in the eco-friendly solvent 2-MeTHF. The Royal Society of Chemistry 2012.
- Pace, Vittorio,Castoldi, Laura,Alcantara, Andres R.,Holzer, Wolfgang
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supporting information; experimental part
p. 1859 - 1863
(2012/08/14)
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- Mechanism-based inactivation of coenzyme B12-dependent 2-methyleneglutarate mutase by (Z)-glutaconate and buta-1,3-diene-2,3- dicarboxylate
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In the presence of holo 2-methyleneglutarate mutase, buta-1,3-diene-2,3- dicarboxylate and (Z)-glutaconate [(Z)-pent-2-ene-1,5-dicarboxylate], but not (E)-glutaconate, each induced homolysis of the Co-C bond of coenzyme B 12 to afford cob(II)alamin and the 5′-deoxyadenosyl radical. The latter probably added to the double bond in (Z)-glutaconate and one of the double bonds in buta-1,3-diene-2,3-dicarboxylate to afford a corresponding "radical adduct". The formation of new radicals and cob(II)alamin was diagnosed by UV/Visible and EPR spectroscopy. (Z)-Glutaconate rapidly inactivated the mutase with formation of aquocobalamin, which was possibly derived by electron transfer from cob(II)alamin to the radical adduct. In contrast, buta-1,3-diene-2,3-dicarboxylate was a much slower inactivator. In this case, the spectroscopic data revealed a relatively stable complex of the radical adduct with cob(II)alamin in the active site of the enzyme. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Buckel, Wolfgang,Pierik, Antonio J.,Plett, Sandra,Alhapel, Ashraf,Suarez, Diana,Tu, Shang-Min,Golding, Bernard T.
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p. 3622 - 3626
(2007/10/03)
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- DIENOPHILIE DES OLEFINES CAPTODATIVES - VI SYNTHESES ET CYCLOADDITIONS DE DIELS-ALDER DES α-ALKYLTHIO-ACRYLATES D'ALKYLE AVEC LE CYCLOPENTADIENE: INFLUENCE DES FACTEURS STERIQUES SUR LA REACTIVITE ET SUR LA STEREOSELECTIVITE
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The Diels-Alder reactions of cyclopentadiene with a series of four α-alkylthio-alkyl acrylates were investigated.Although slightly slower than the reactions of unsubstituted alkyl acrylates, the spontaneous cycloadditions of these captodative olefins occur at room temperature affording adducts in excellent yield.The steric effect of the ester function is found to be more important in determining the dienophilic reactivity than the endo/exo ratios of the adducts and increase in the size of the alkylthio group reduces the endo selectivity of that group from 66-69percent (for methylthio) to 25-22percent (for tertiobutylthio group).The aluminium trichloride complexed methoxycarbonyl group leads to a very high endo-stereoselectivity (97percent) of that group.
- Boucher, Jean-Luc,Stella, Lucien
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p. 3595 - 3606
(2007/10/02)
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