50418-39-8Relevant academic research and scientific papers
REGIO- AND STEREOSPECIFIC CONSTRUCTION OF VICINAL QUATERNARY CARBONS: TOTAL SYNTHESIS OF (+/-)-ALBENE
Srikrishna, Adusumilli,Nagaraju, Sankuratri
, p. 1699 - 1704 (1995)
A regiospecific and stereoselective total synthesis of the trisnorsesquiterpene (+/-)-albene, via a prochiral precursor is described.The ortho ester Claisen rearrangement of the allyl alcohol, obtained in two regiospecific reactions from a Diels-Alder adduct, followed by hydrolysis of the resultant ester furnished an ene acid in a highly stereoselective manner.Anhydrous copper sulphate catalysed intramolecular cyclopropanation reaction of the diazo ketone derived from the ene acid, generated a cyclopropyl ketone.The regiospecific reductive cleavage of this cyclopropyl ketone resulted in a prochiral ketone.Finally, Shapiro reaction on the tosylhydrazone, derived from the latter ketone, furnished (+/-)-albene. - Keywords: Albene; quaternary carbons; Claisen rearrangement; diazo ketone; cyclopropanation; reductive cyclopropane cleavage; Shapiro reaction.
Mild and efficient boronic acid catalysis of Diels-Alder cycloadditions to 2-alkynoic acids
Zheng, Hongchao,Hall, Dennis G.
supporting information; experimental part, p. 3561 - 3564 (2010/08/07)
The concept of boronic acid catalysis (BAC) for the activation of unsaturated carboxylic acids is applied to the Diels-Alder cycloaddition between 2-alkynoic acids as dienophiles and various dienes. These [4+2] cycloadditions produce cyclohexadienyl carboxylic acids, which can be oxidized in situ to produce polysubstituted aromatic carboxylic acids. The boronic acid catalyst is suspected to provide activation by a LUMO-lowering effect of the unsaturated carboxylic acid likely via a covalent, monoacylated hemiboronic ester intermediate.
Experiments towards the Generation of 1,5- and 2,3-Didehydroquadricyclanes
Heywang, Ulrich,Szeimies, Guenter
, p. 121 - 131 (2007/10/02)
Metalation of the (hydroxymethyl)quadricyclanes 7a - c with n-butyllithium in ether is determined mostly by the chelating effect of the CH2O-Li group and only to a lesser extent by the magnitude of the 13C-1H coupling constant of the position to be lithiated in the corresponding quadricyclane derivative.Similar results were obtained for 3-quadricyclanol (20a).Treatment of the bromide 26a, prepared by lithiation of 7b, with strong bases apparently generates the 1,2-didehydroquadricyclane 34.and not the 1,5-didehydroquadricyclane 35.Attempts to convert the dihalide 9 into the 2,3-didehydroquadricyclane 4 were unsuccessful.
Terpenes and Terpene Derivatives, XI. - Synthesis and Reductions of β-Santalenone hept-2-yl)-3-penten-2-one>
Simmross, Frank-Michael,Weyerstahl, Peter
, p. 1089 - 1099 (2007/10/02)
Starting from cyclopentadiene (2) and 2-butynoic acid (3), and via the acids 5 and 7, the allyl alcohol 9 has been prepared. 9 reacts with the dienol ether 10 to give β-santalenone 11.Reduction of 11 with LiAlH4/AlCl3 yields, depending on the reaction temperature various amounts of hydrocarbons 25, 26, and β-santalenone (1), of the ketone 27 and of the alcohol 28.With NaBH4 the alcohols 28 and 29 have been obtained.
Desaminierungsreaktionen, 36. Zerfall von Methylnorbornan-2-diazonium-Ionen
Kirmse, Wolfgang,Hartmann, Marianne,Siegfried, Rainer,Wroblowsky, Heinz-Juergen,Zang, Brigitte,Zellmer, Volker
, p. 1793 - 1808 (2007/10/02)
3-, 5-, 6- and 7-Methylnorbornane-2-diazonium ions were generated as exo/endo mixtures by photolysis of the corresponding methyl-2-norbornane tosylhydrazones (3, 5, 23, 27, 32, 34, 45, 47) in aqueous sodium hydroxide.The composition of the methyl-2-exo-no
