Ring‐Closing Metathesis at Room Temperature within Nanometer Micelles using Water as the Only Solvent

Abstract

Simply mixing a water-insoluble diolefinic substrate and Grubbs second generation catalyst in pure water containing small amounts of the amphiphile polyoxyethanyl a-tocopheryl sebacate (PTS) leads to efficient ring-closing metathesis.

Suzuki–Miyaura Cross‐Coupling Reactions in Aqueous Media: Green and Sustainable Syntheses of Biaryls

“…[89,90] They disclosed that inexpensive and commercially available nonionic amphiphiles such as Triton X-100 or the vitamin E-derived polyoxyethanyl a-tocopheryl sebacate (PTS; Scheme 44) form nanometer-sized particles in water and promote Heck cross-couplings of non-water-soluble partners at ambient temperatures. [91] Concerning the SuzukiMiyaura reaction, the authors established that the coupling of aryl iodide with arylboronic acids requires only 1-2 wt % PTS in water in presence of 2 mol % of the PdCl 2 {1,1'-bis(di-tert-butylphosphino)ferrocene} (abbreviated Pd(dtbpf)Cl 2 ) at ambient temperature.…”

Aqueous Olefin Metathesis

“…[35] The formation of larger rings was not attempted. [34] A completely different strategy was chosen by Bowden and co-workers, who reported a new method for the heterogenization of the Grubbs first-and secondgeneration catalysts. [36] They occluded 2 a and 2 b in a slab of polydimethylsiloxane (PDMS) and used this material in various metathesis reactions in aqueous media.…”

“…[33] This powerful methodology was also used to effect the ring-closing metathesis in air of lipophilic substrates in the presence of 2 b in water. [34] Water containing only 0.8-2.5 mol % of PTS served admirably as a reaction medium for the preparation of five-to seven-membered cyclic products (Scheme 13). The formation of product 47, which contains a tetrasubstituted CÀC double bond, is particularly noteworthy; this reaction is considered to be very challenging even in organic solvents.…”

Sustainable Chemistry Metrics

“…[54] In all cases, metathesis reactions lead to efficient atom economic synthetic approaches towards acyclic structures, cyclic and macrocylic molecules, and polymers. Sometimes ethene is produced as byproduct but, in most cases, its molecular weight represents only a low mass percentage in comparison with the final product.…”