- Cp2TiCl2-catalyzed hydrocarboxylation of alkynes with CO2: formation of α,β-unsaturated carboxylic acids
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Cp2TiCl2-catalyzed hydrocarboxylation of alkynes with CO2 (atmospheric pressure) has been reported. A range of alkynes were transformed to the corresponding α,β-unsaturated carboxylic acids in high yields with high regioselectivity. The reaction proceeded with hydrotitanation, transmetalation, and subsequently carboxylation with CO2
- Shao, Peng,Wang, Sheng,Du, Gaixia,Xi, Chanjuan
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p. 3534 - 3539
(2017/01/25)
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- Asymmetric dihydroxylation of β,γ-unsaturated carboxylic esters with trisubstituted C=C bonds - Enantioselective syntheses of trisubstituted γ-butyrolactones
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β,γ-Unsaturated esters with stereodefined trisubstitued C=C double bonds were prepared by the Arndt-Eistert homologation of α,β-unsaturated carboxyl halides, by two-step methoxycarbonylation of allylbarium reagents, by deconjugation of α,β-unsaturated esters, and by Horner-Wadsworth-Emmons variants of the Stobbe condensation. Sharpless asymmetric dihydroxylation of the β,γ-unsaturated esters, followed by spontaneous cyclization, afforded β-hydroxy-γ-lactones in moderate to good yields and with enantiomeric excesses of up to 97 %. Similarly, tetrahydroxy-γ-lactones were obtained from diunsaturated esters; these lactones were converted into a bislactone and an unsaturated β-hydroxy γ-lactone. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Kapferer, Tobias,Brueckner, Reinhard
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p. 2119 - 2133
(2007/10/03)
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- Cp2ZrCl2-mediated three-component coupling reactions of CO2, ethylene (or alkynes), and electrophiles leading to carboxylic acid derivatives
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Zirconacycles 1 and 2 can be simply generated from Cp2ZrCl 2, EtMgBr, and an atmospheric pressure of CO2. The treatment of Cp2ZrCl2 with EtMgBr followed by exposure to CO2 generates zirconacycle 1, which can react with various electrophiles to give a variety of carboxylic acid derivatives. Unsaturated zirconacycles 2 can also generated from Cp2ZrCl2, EtMgBr, alkynes, and CO2. Complexes 2 react with electrophiles to give α,β-unsaturated acids stereoselectively.
- Yamashita, Kohei,Chatani, Naoto
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p. 919 - 922
(2007/10/03)
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- Structure-activity relationships of unsaturated analogues of valproic acid
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The principal metabolite of valproic acid (VPA), 2-ene VPA, appears to share most of VPA's pharmacological and therapeutic properties while lacking its hepatotoxicity and teratogenicity, thus making it a useful lead compound for the development of safer antiepileptic drugs. Analogues of 2-ene VPA were evaluated for anticonvulsant activity in mice using the subcutaneous pentylenetetrazole test. Cyclooctylideneacetic acid exhibited a potency markedly exceeding that of VPA itself with only modest levels of sedation. Potency, as either ED50 or brain concentration, was highly correlated (r > 0.85) with volume and lipophilicity rather than with one of the shape parameters calculated by molecular modeling techniques, arguing against the existence of a specific receptor site. Instead, a role for the plasma membrane in mediating the anticonvulsant effect is suggested.
- Palaty,Abbott
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p. 3398 - 3406
(2007/10/02)
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