479682-88-7Relevant academic research and scientific papers
Ruthenium-catalyzed olefin metathesis double-bond isomerization sequence
Schmidt, Bernd
, p. 7672 - 7687 (2007/10/03)
A novel ruthenium-catalyzed tandem ring-closing metathesis (RCM) double-bond isomerization reaction is described in this paper. The utility of this method for the efficient syntheses of five-, six-, and seven-membered cyclic enol ethers is demonstrated. It relies on the conversion of a metathesis-active ruthenium carbene species to an isomerization-active ruthenium-hydride species in situ. This conversion is achieved by using various additives. Scope and limitations of the different protocols are discussed, and some mechanistic considerations based on 31P and 1H NMR spectroscopic studies are presented.
An olefin metathesis/double bond isomerization sequence catalyzed by an in situ generated ruthenium hydride species
Schmidt, Bernd
, p. 816 - 819 (2007/10/03)
The direct conversion of allyl ethers to cyclic enol ethers using an olefin metathesis/double bond migration sequence is described. Ruthenium carbene complexes were activated to catalyze the double bond migration step by addition of hydride sources, such
Tandem olefin metathesis/hydrogenation at ambient temperature: Activation of ruthenium carbene complexes by addition of hydrides
Schmidt, Bernd,Pohler, Michael
, p. 2512 - 2517 (2007/10/03)
Sodium hydride activates ruthenium carbene complexes to catalyze hydrogenation reactions subsequent to ring closing olefin metathesis. Under these conditions, hydrogenation of cyclopentenols proceeds smoothly at ambient temperature and under 1 atm of hydrogen in toluene. An alternative protocol was developed that involves the formation of hydrogen in situ by reaction of excess sodium hydride with protic functional groups and water.
Conversion of (Z)-1,4-dihydroxyalk-2-enes into 2,5-dihydrofurans and of alkane-1,4-diols into tetrahydrofurans via acid-catalysed cyclisation of the monoisoureas formed by their copper(I)-mediated reactions with dicyclohexylcarbodiimide
Duffy, Michael G.,Grayson, David H.
, p. 1555 - 1563 (2007/10/03)
(Z)-1,4-dihydroxyalk-2-enes were converted into 2,5-dihydrofurans and alkane-1,4-diols were converted into tetrahydrofurans via acid-catalysed cyclisation of the monoisoureas. The reaction involved protonation of the carbodiimide by acidic phenol followed by reaction with alkanol. Pd/CaCo3-quinoline catalyst system was employed in the presence of a little triethylamine to overcome partial hydrogenolysis.
