Preparation of trialkyl-substituted olefins by ruthenium catalyzed cross-metathesis

Rhodium-Catalyzed Endo-Selective Epoxide-Opening Cascades: Formal Synthesis of (−)-Brevisin

“…Motivated by reports of higher yields in cross metathesis of allyl groups with increased steric hindrance, 27 alkene 16 was prepared from 15 via cross metathesis with 2-methyl-2-butene. 28 In comparison, cross metathesis of 18 and trisubstituted alkene 16 provided a significantly higher yield, particularly when performed in the absence of additional solvent.…”

Computational Modeling of Renewable Molecules. Ruthenium Alkylidene-Mediated Metathesis of Trialkyl-Substituted Olefins

“…Metathesis of trisubstituted olefins, in general, proceeded with poor cis−trans ( Z , E ) selectivities. ,− The computational modeling also demonstrates that the low stereoselectivity of olefin metathesis is due to close activation energies for the cis and trans isomer formation and the fast cis−trans isomerization caused by the catalyst . Numerous experiments demonstrated that the metathesis reaction is accompanied by the cis−trans isomerization, reaching, in general, the equilibrium state…”

Cross‐Metathesis Reactions of Homoallyl Methyl Malonates with Sterically Hindered Allylic Esters

“…The development of this research enhanced our interest in the synthesis of intermediates of general structure A containing a trisubstituted double bond (Scheme ). Taking aside the importance of trisubstituted double bond subunits in natural products,2e such intermediates could be subsequently transformed into lactone skeletons, either by an intramolecular metal‐catalyzed allylic alkylation (Scheme , path a)5 or by oxidative radical cyclization (Scheme , path b) 6. A concise retrosynthetic analysis carried out on compounds A , and the resulting disconnection of their trisubstituted double bond, clearly indicate CM of homoallyl malonate 1 and allyl esters B as a convenient approach for their preparation.…”