A chemo- and stereoselective reduction of cycloalkynes to (E)-cycloalkenes
作者:Alois Fürstner、Karin Radkowski
DOI:10.1039/b207169j
日期:——
A stereoselective entry into (E)-cycloalkenes is described, comprising the ring closing alkyne metathesis (RCAM) of suitable diynes, a ruthenium-catalyzed trans-selective hydrosilylation of the cycloalkynes thus formed, followed by a desilylation of the resulting vinylsilanes mediated by AgF.
Ruthenium-Catalyzed <i>trans</i>-Hydroalkynylation and <i>trans</i>-Chloroalkynylation of Internal Alkynes
作者:Nagaraju Barsu、Markus Leutzsch、Alois Fürstner
DOI:10.1021/jacs.0c08582
日期:2020.11.4
[Cp*RuCl]4 catalyzes the addition of iPr3SiC≡CX (X = H, Cl) across internal alkynes with formation of 1,3-enyne or 1-chloro-1,3-enyne derivatives, respectively; the reaction follows an unorthodox trans-addition mode. The well-balanced affinities of the different reaction partners to the ruthenium catalyst ensure that crossed addition prevails over homodimerization of the individual components, as can
Synthèses de produits macrocycliques à odeur musquée. 8e communication Synthèse de la civettone naturelle
作者:M. Stoll、J. Hulstkamp、A. Rouvé
DOI:10.1002/hlca.19480310234
日期:——
e d'éthyle a été cyelisé en l'éthylène-cétal de la céto-9-cyclo-heptadécanol-1-one-17. Cette dernière a été réduite catalytiquement en l'éthy1ène-cétal des deux céto-9-cyclo-heptadécane-diol-l,17 diastéreoméres. Ceux-ci furent transformés en les deux bromo-aeétates correspondants qui donnèrent, par réduction au zinc, un mélange de civettone trans et de civettone cis.
A concise, practical and stereoselective entry into macrocyclic (E)-alkenes is outlined comprising a sequence of ring closing alkyne metathesis (RCAM), trans-selective hydrosilylation of the resulting cycloalkynes catalyzed by [Cp*Ru(MeCN)(3)]PF6, and a protodesilylation of the ensuing vinylsilanes with AgF in aq. THF/MeOH. Moreover, the first examples of intramolecular enyne-yne metathesis reactions catalyzed by the Schrock alkylidyne complex (tBUO)(3)W drop CCMe3 are reported; the resulting cyclic enynes can be converted along similar lines into the corresponding (E,E)-configured 1,3-dienes in good overall yields. Cycloalkyne 4 and the (E)-configured cyclic olefins 6 and 21 were characterized by X-ray crystallography. (C) 2004 Elsevier Ltd. All rights reserved.
Ring closing alkyne metathesis: stereoselective synthesis of civetone
作者:Alois Fürstner、Günter Seidel
DOI:10.1016/s0022-328x(00)00096-6
日期:2000.7
A concise and stereoselective synthesis of the macrocyclic musk civetone 6 is reported starting from readily available 9-undecynol. The key steps comprise a ring closing metathesis of diyne 4 followed by Lindlar reduction of the resulting cycloalkyne 5. The cyclization can be effected either by using catalytic amounts of the Schrock alkylidyne complex (t-BuO)(3)W drop CCMe3 or by means of an in situ catalyst mixture generated from Mo(CO)(6) and p-trifluoromethylphenol. Both catalyst systems turned out to be compatible with the unprotected ketone function of the substrate. (C) 2000 Elsevier Science S.A. All rights reserved.