699-95-6Relevant articles and documents
Mechanistic and Kinetic Studies of the Ring Opening Metathesis Polymerization of Norbornenyl Monomers by a Grubbs Third Generation Catalyst
Hyatt, Michael G.,Walsh, Dylan J.,Lord, Richard L.,Andino Martinez, José G.,Guironnet, Damien
supporting information, p. 17918 - 17925 (2019/11/11)
The mechanism of ring-opening metathesis polymerization (ROMP) for a set of functionalized norbornenyl monomers initiated by a Grubbs third generation precatalyst [(H2IMes)(pyr)2(Cl)2Ru═CHPh] was investigated. Through a series of 12C/13C and 1H/2H kinetic isotope effect studies, the rate-determining step for the polymerization was determined to be the formation of the metallacyclobutane ring. This experimental result was further validated through DFT calculations showing that the highest energy transition state is metallacyclobutane formation. The effect of monomer stereochemistry (exo vs endo) of two types of ester substituted monomers was also investigated. Kinetic and spectroscopic evidence supporting the formation of a six-membered chelate through coordination of the proximal polymer ester to the Ru center is presented. This chelation and its impact on the rate of polymerization are shown to vary based on the monomer employed and its stereochemistry. The combination of this knowledge led to the derivation of a generic rate law describing the rate of polymerization of norbornene monomers initiated by a Grubbs third generation catalyst.
Microbial alcohol dehydrogenase screening for enantiopure lactone synthesis: Down-stream process from microtiter plate to bench bioreactor
Boratyński,Pannek,Walczak,Janik-Polanowicz,Huszcza,Szczepańska,Martinez-Rojas,Olejniczak
, p. 1637 - 1646 (2015/02/05)
One-pot conversion with whole cells of bacteria was performed for biooxidation of meso monocyclic (3a-b) and bicyclic diols (3c-e) into corresponding chiral lactones of bicyclo[4.3.0]nonane structure (2a-b) as well as exo- and endo-bridged lactones with the structure of [2.2.1] (3c-d) and [2.2.2] (3e). Micrococcus sp. DSM 30771 was selected as biocatalyst with significant alcohol dehydrogenase activity. Among tested strains, microbial oxidation of meso diols 3a-e catalyzed by Micrococcus sp. afforded enantiomerically pure ((+)-(2S,3R)-2c (ee = 99%), (+)-(2S,3R)-2e (ee = 99%)) or enriched ((+)-(1S,5R)-2a (ee = 90%), (-)-(1S,5R)-2b (ee = 86%), (+)-(2S,3R)-2d (ee = 80%)) lactone moieties. Comparative study with respect to microbial cultivation as well as biooxidation was undertaken to verify agreement of secondary metabolite biosynthesis in different scales: from MTP (4 mL), across shake flask (100 mL) till bioreactor (4 L). The results from biotransformations showed quite similar dependence in oxidation of all substrates 3a-e in MTP and flasks as well, thereby confirmed the validity and reasonable approach of using MTP for preliminary studies.
ROMP-derived oligomeric phosphates for application in facile benzylation
Long, Toby R.,Maity, Pradip K.,Samarakoon, Thiwanka B.,Hanson, Paul R.
supporting information; experimental part, p. 2904 - 2907 (2010/09/30)
The development of new ROMP-based oligomeric benzyl phosphates (OBP n) is reported for use as soluble, stable benzylating reagents. These oligomeric reagents are readily synthesized from commercially available materials and conveniently polymerized and purified in a one-pot process, affording bench-stable, pure white, free-flowing solids on multigram scale. Utilization in benzylation reactions with a variety of nucleophiles is reported.
