- Synthesis of highly substituted γ-butyrolactones by a gold-catalyzed cascade reaction of benzyl esters
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Easily accessible benzylic esters of 3-butynoic acids in a gold-catalyzed cyclization/rearrangement cascade reaction provided 3-propargyl γ-butyrolactones with the alkene and the carbonyl group not being conjugated. Crossover experiments showed that the formation of the new C-C bond is an intermolecular process. Initially propargylic-benzylic esters were used, but alkyl-substituted benzylic esters worked equally well. In the case of the propargylic- benzylic products, a simple treatment of the products with aluminum oxide initiated a twofold tautomerization to the allenyl-substituted g-butyrolactones with conjugation of the carbonyl group, the olefin, and the allene. The synthetic sequence can be conducted stepwise or as a one-pot cascade reaction with similar yields. Even in the presence of the gold catalyst the new allene remains intact.
- Jaimes, Maria Camila Blanco,Ahrens, Alexander,Pfl?sterer, Daniel,Rudolph, Matthias,Hashmi, A. Stephen K.
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supporting information
p. 427 - 433
(2015/02/18)
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- CaSR ANTAGONIST
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The present invention provides a compound having a calcium-sensitive receptor antagonistic action, a pharmaceutical composition containing the compound, particularly a calcium receptor antagonist and a therapeutic drug for osteoporosis. A compound represented by the following formula (1), a pharmaceutically acceptable salt thereof or an optically active form thereof: wherein each symbol is as defined in the description.
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Page/Page column 48-49
(2008/06/13)
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- Determining the σ-donor ability of the cyclopropane C-C bond
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The low temperature crystal structures of ester and ether derivatives of varying electron demand, derived from cyclopropylmethanol 8 and dicyclopropylmethanol 9, have been determined. These structures show a very strong response of the C-OR bond distance to the electron demand of the OR substituent, demonstrating the strong σ-donor ability of the strained C-C bonds in the cyclopropane ring. The Royal Society of Chemistry 2005.
- Fifer, Nathan L.,White, Jonathan M.
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p. 1776 - 1780
(2007/10/03)
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- Dimerization of Cyclopropanecarboxylic Acid Dianion and Thermal Decarboxylative Rearrangement of the Dimer to 2-Cyclopropyl-4,5-dihydrofuran
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The dianion of cyclopropanecarboxylic acid (2) reacted with alkyl halides and deuterated water at temperatures below 0 deg C; however, self-condensation to the β-keto acid 3 was the only observed product at elevated temperatures.This observation contrasts the self-condensation of the ethyl ester where a trimeric diester alcohol is the product.Attempted mixed condensations of the dianion 2 and carboxylic acids without acidic α-protons did not proceed as well, 3 being the major product.Thermal decarboxylation of 3 did not yield the expected dicyclopropyl ketone; rather , a facile rearrangement in a sealed tube at 120 deg C occured, giving rise to 2-cyclopropyl-4,5-dihydrofuran.This "vinyl-cyclopropyl" type rearrangement does not occur through dicyclopropyl ketone or its enolate.
- Jahngen, Edwin G. E.,Phillips, Douglas,Kobelski, Robert J.,Demko, Donald M.
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p. 2472 - 2476
(2007/10/02)
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