Progress in Metathesis Through Natural Product Synthesis

Abstract

This article covers case studies in natural product syntheses with comments on various aspects of metathesis reactions and on how the difficulties encountered in these syntheses have led to better understanding of these reactions or to more effective reaction conditions and catalysts. Ring‐closingmetathesis leading to small and medium‐sized rings is discussed, followed by macrocycle formation, asymmetric ring‐closing metathesis, and cross metathesis.

Sequential Alkene Isomerization and Ring‐Closing Metathesis in Production of Macrocyclic Musks from Biomass

“…Reactions were performed in toluene in 50 8Cfor 5h.Itisw ell known fact that during the metathesis reactiont he catalyst undergoes ad ecomposition process leading to ruthenium species, which can lead to further isomerization of double bonds in both substrates and products, therefore tetrafluorobenzoquinone was added as aR u ÀHs cavenger. [30] Based on various examples of RCM macrocyclisations availableinl iterature, [31][32][33] we chose to keep the substrate concentration near 1.5 mm.A ccordingt ot he general optimized procedure, we performed several RCM reactions obtaining macrocyclic lactones with different ring sizes (Table 3), varying from 15 to 19 atoms. Wes tarted with RCM of the non-isomerized oleic substrate, dec-9-en-1-yl dec-9-enoate (3,e ntry 1) leadingt oamacrocyclic lactone 4 with the 19 atoms in the ring in 78 %y ield.…”

Chemodiscrimination of Olefin Bonds Through Cross‐Metathesis Reactions – Synthesis of Functionalized β‐Lactam and β‐Amino Acid Derivatives

“…Metathesis reactions have become increasingly important and widely applied in synthetic organic chemistry over the past twenty years allowing access to various small organic molecules, sophisticated biomolecules, and functional moieties. [1][2][3][4][5][6][7][8][9][10][11] However, regioselective or chemoselective metathesis, which is often catalyst or substrate dependent, still remains a challenge in synthetic chemistry. [12] Steric or electronic factors may contribute to the outcome of metathesis in terms of selectivity.…”

Metathetic Synthesis of Common and Medium-Sized Lactones: The State of the Art

“…When the development of well-defined ruthenium and molybdenum carbene complexes in the early nineties had disclosed the great potential of olefin metathesis (OM) in the synthesis of cyclic molecules [43][44][45][46], the ring-closing metathesis (RCM) approach to unsaturated lactones has witnessed increasing success. Various accounts have included details on the synthesis of lactones by RCM [47][48][49][50][51][52].…”