- 1,5-BIS(TRIMETHYLSILOXY)-1,5-DIMETHOXY-1,4-PENTADIENES. CYCLOPROPANE SYNTHESIS VIA INTRAMOLECULAR COUPLING.
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The title compounds (1a-e) can be prepared in good yield by silylation of the dianions of dimethyl glutarates (2a-e).On treatment with titanium tetrachloride, they cyclise stereoselectively to dimethyl trans-cyclopropane-1,2-dicarboxylates.
- Chan, T. H.,Wallace, I. H. M.
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- Synthesis of racemic cis-1-alkyl- and 1-aryl-2-aminocyclopropanecarboxylic esters
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The title cyclic β-amino esters were synthesized stereo- and regioselectively. Starting from the corresponding 1-aryl- and 1-alkylcyclopropane-1,2-dicarboxylates, selective monosaponification and subsequent Curtius reaction leads to certain cis-1-alkyl- and 1-aryl-2-aminocyclopropanecarboxylic esters. These β-aminocyclopropanecarboxylate derivatives (β-ACCs) can be seen as useful building blocks for β-peptides.
- Mangelinckx, Sven,De Kimpe, Norbert
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p. 1771 - 1774
(2007/10/03)
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- Synthesis and mode of action of 1-substituted trans-cyclopropane 1,2-dicarboxylic acids: Inhibitors of the methylaspartase reaction
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A range of 1-substituted cyclopropane 1,2-dicarboxylic acids are synthesised using short efficient routes and are found to be good to potent inhibitors of 3-methylaspartase; the crystallographically determined absolute stereochemistry and the mode of acti
- Badiani, Kamal,Lightfoot, Philip,Gani, David
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p. 675 - 677
(2007/10/03)
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- Hinweise auf einen Fragmentierungsmechanismus bei Coenzym-B12-abhaengigen Umlagerungen des Kohlenstoffgeruests
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Keywords: Coenzym B12, Enzymkatalyse, Umlagerungen
- Beatrix, Birgitta,Zelder, Oskar,Kroll, Friedrich K.,Oerlygsson, Gissur,Golding, Bernard T.,Buckel, Wolfgang
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p. 2573 - 2576
(2007/10/03)
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- Cyclopropanediamines, 3. - Pure Diastereomers of 1,2-Cyclopropanedicarboxylic Acids and Derivatives
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Efficient preparations of pure diastereomers of dimethyl 1,2-cyclopropanedicarboxylates 2, dicarboxylic acids 3, dicarbonyl dichlorides 4, and dihydrazides 5 are reported.Mixtures of diastereomers of dimethyl dicarboxylates 2a, b, d, e are obtained from α,β-unsaturated methyl carboxylates 7 and methyl α-chlorocarboxylates 8 as well as from 7c, d and the sulfur ylide 10 (2c, d).The diastereomers are separated by fractionating distillations (2a, b, c, e) or crystallization (2d) on a 100-g to 1-kg scale (d.e. >99percent).Only low yields of 2c are obtained in the reaction of methyl crotonate (7c) with methyl α-chloroacetate (8a), since 7c predominantly dimerizes to afford 12.The diesters 2 are converted into the pure diastereomeric diacids 3, dicarbonyl dichlorides 4, and dihydrazides 5. 3,3-Dimethyl-cis-1,2-cyclopropanedicarboxylic acid (cis-3f) is obtained by trans-->cis isomerization of trans-3f with the help of acetic anhydride and sodium acetate as catalyst.The configurations of 2-6 and 12 are confirmed by 1H NMR spectroscopy.Derivatives of cis-1,2-dimethyl-1,2-cyclopropanedicarboxylic acid tend to form bicyclic products.Thus, the reaction of cis-3e with phosphorus pentachloride yields mainly the cyclic anhydride 6e and only small amounts of the dicarbonyl dichloride cis-4e.Furthermore, the dihydrazide cis-5e slowly cyclizes in the solid state to give the N-aminoimide 13 and hydrazine, a reaction which is fast in solution.Pure 13 is obtained by thermolysis of cis-5e at 60-65 deg C under high vacuum.
- Saal, Wolfgang von der,Reinhardt, Robert,Seidenspinner, Hubert-Matthias,Stawitz, Josef,Quast, Helmut
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p. 703 - 712
(2007/10/02)
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- 1,5-BIS(TRIMETHYLSILOXY)-1,5-DIMETHOXY-1, 4-PENTADIENES PRECURSORS FOR THE SYNTHESIS OF CYCLOPROPANES AND CYCLOBUTANES
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1,5-Bis(trimethylsiloxy)-1,5-dimethoxy-1,4-pentadienes (7) can be prepared in good yield by silylation of the dianions of dimethyl glutarates (8).On treatment with titanium tetrachloride, 7 cyclise stereoselectively to dimethyl trans-cyclopropane-1,2-dica
- Wallace, I. H. M.,Chan, T. H.
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p. 847 - 854
(2007/10/02)
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