For site-selective protein modification these transformations cross metathesis of unsaturated amino acids revealed that re-activity in metathesis increased with . Quigley et al – supporting information – s1 supporting information for ruthenium-catalysed z-selective cross metathesis of allylic-substituted olefins brendan l quigley and robert h grubbs. The z-selective cross metathesis of allylic-substituted olefins is explored with recently developed ruthenium-based metathesis catalysts the reaction proceeds with excellent stereoselectivity for the z-isomer (typically 95%) and yields of up to 88% for a variety of allylic substituents. The efficient and selective cross‐metathesis (cm) of both the α‐ and β‐anomers of c‐allyl‐glucose and n‐acetyl‐c‐allyl‐glucosamine with electron‐deficient olefins is reported.
Cross-metathesis (cm) is typically e-selective, with the largest substituents trans disposed across the double bond, owing to the lower energy of e-alkenes and the reversible nature of the om reaction pathway. Kinetically controlled e-selective catalytic olefin metathesis a significant shortcoming in olefin metathesis, a chemical process that is central to research in several branches of chemistry, is the complete lack of efficient methods that kinetically favor e-isomers in the product distribution. Selective synthesis of (2z,4e) cross metathesis of n-allylamines and α,β-unsaturated carbonyl compounds: a one-pot synthesis of substituted pyrroles.
Department of chemistry raffaele colombo 12/06/2014 catalytic z‑selective cross-metathesis in complex molecule synthesis: a convergent stereoselective route to . Kinetically controlled e-selective catalytic olefin metathesis thach t here we show that kinetically e-selective cross-metathesis reactions may be designed to . Indeed, cross metathesis of two different alkenes can be accompanied by metathesis of individual substrates to afford a mixture of e and z isomers of symmetrical and unsymmetrical coupling products 13 one example of such a reaction between allylbenzene and different alkenes (including styrenes) has been recently reported to give all possible . Those amino acids that generally lead to lower conversion (ie, arginine) could undergo selective cross metathesis in the presence of a more highly reactive substrate moreover, the steric environments around the olefin and allylic heteroatoms were shown to impact the efficiency of z -selective cm.
Here we show that kinetically e-selective cross-metathesis reactions may be designed to generate thermodynamically disfavored alkenyl chlorides and fluorides in high yield and with exceptional stereoselectivity. First published on 30th october 2013 the z-selective cross metathesis of allylic-substituted olefins is explored with recently developed ruthenium-based metathesis catalysts. Chemists report e-selective macrocyclic ring-closing metathesis new catalytic approach highly efficient and selective in preparation of anti-cancer agent pacritinib. However it has been shown that the use of selective cross metathesis makes these reactions possible – selective metathesis can result in slow secondary.
However, an ongoing challenge in cross metathesis in preparing z-selective metathesis catalysts, a continuing need in the art exists for improved . The kinetically e-selective cross-metathesis reactions is designed to generate thermodynamically disfavored alkenyl chlorides and fluorides in high yield and with exceptional stereoselectivity. While recent advances have uncovered a family of (z)-selective olefin metathesis catalysts, complexes capable of kinetically controlled (e)-selective cross metathesis remain elusive (furstner, a, teaching metathesis “simple” stereochemistry.
Recent advances in z-selective olefin metathesis min zhou 20150505 hu group, sioc hu group, sioc z-selective cm(cross-metathesis) reaction. Cross-metathesis of z-1,2-dichloroethene and various types of olefins are exceptionally efficient and stereoselective with the mac complex mo-5b, which can also promote z-selective cross . Here, we show that kinetically e-selective cross-metathesis reactions may be designed to generate thermodynamically disfavored alkenyl chlorides and fluorides in high yield and with exceptional stereoselectivity.
Type or paste a doi name into the text box research in the lambert group is focused in the area of catalysis we are especially interested in the development of novel catalytic strategies for selective organic e selective cross metathesis. Kinetically controlled z-selective rcm reactions have been reported, but the only available metathesis approach for accessing macrocyclic e-olefins entails selective removal of the z-component of . Olefin cross metathesis is a particularly powerful transformation that has been exploited extensively for the formation of complex products until recently, however, constructing z-olefins using this methodology was not possible.