93379-40-9Relevant academic research and scientific papers
RECYCLABLE POLYMERS BASED ON RING-FUSED GAMMA-BUTYROLACTONES
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Page/Page column 34; 39, (2020/02/23)
The invention discloses a class of new polymers, trans-ring-fused poly(4-hydroxybutyrate)s (RF-P4HB) that exhibit a unique set of properties, including robust thermal stability and mechanical strength, quantitative recyclability to the building block monomers via thermolysis and/or chemical catalysis, and convenient production from the chemical ring-opening polymerization under ambient temperature and pressure. Another unique property is the formation of crystalline stereocomplexed polymers with high melting temperature upon mixing the two enantiomeric RF-P4HB chains via stereocomplexing co-crystallization. This invention also provides the corresponding ring-fused lactone monomer structures that enable the synthesis of the RF-P4HB polymers, through trans-fusing of rings to the parent γ-butyrolactone ring. Furthermore, a polymerization or copolymerization process for the synthesis of RF-P4HB polymers and copolymers is disclosed.
Annulated and bridged tetrahydrofurans from alkenoxyl radical cyclization
Schur, Christine,Kelm, Harald,Gottwald, Thomas,Ludwig, Arne,Kneuer, Rainer,Hartung, Jens
supporting information, p. 8288 - 8307 (2015/01/09)
4-Pentenoxyl radicals sharing two or more carbon atoms with a cycloalkane cyclize in a predictable manner stereoselectively and regioselectively to afford in solutions of bromotrichloromethane cycloalkyl-fused or -bridged 2-bromomethyltetrahydrofurans in up to 95% yield. Stereoselectivity in alkenoxyl radical ring closures arises from cumulative steric effects. The substituent positioned the closest to the alkene carbon, which is being attacked by the oxygen radical, exerts the strongest stereodirecting effect. This principal inductor guides 5-exo-cyclization 2,3-trans- or 2,4-cis-selectively. The substituent located further from the attacked π-bond is the secondary inductor. A secondary inductor in the relative trans-configuration enhances stereodifferentiation by the primary inductor; a cis-configured secondary inductor decreases this effect. A secondary inductor is not able to overrule the guiding effect of a similar sized primary inductor. Intramolecular 4-pentenoxyl radical additions to a cyclohexene-bound exo-methylene group or to endocyclic double bonds proceed cis-specifically, as exemplified by synthesis of a diastereomerically pure bromobicyclo[2.2.1]heptyl-annulated tetrahydrofuran from the verbenylethyloxyl radical. According to theory, the experimental 2,3-cis-specificity in alkoxyl radical cyclization to an endocyclic π-bond arises from strain associated with the 2,3-trans-ring closure. This journal is
Enzymes in Organic Synthesis. 24. Preparations of Enantiomerically Pure Chiral Lactones via Stereospecific Horse Liver Alcohol Dehydrogenase Catalyzed Oxidations of Monocyclic Meso Diols
Jakovac, Ignac J.,Goodbrand, H. Bruce,Lok, Kar P.,Jones, J. Bryan
, p. 4659 - 4665 (2007/10/02)
Preparative-scale horse liver alcohol dehydrogenase catalyzed oxidation of monocyclic meso diols provides a direct and convenient one-step route to a broad range of chiral γ-lactones of value as synthons in asymmetric synthesis.The general applicability of the method is demonstrated by oxidations of cis-1,2-bis(hydroxymethyl) substrates of the cyclohexyl, cyclohexenyl, cyclopentyl, cyclobutyl, cyclopropyl, and dimethylcyclopropyl series.For each diol, oxidation of the hydroxymethyl group attached to the S chiral center occurs exclusively, and the pure γ-lactone products are isolated in high (68-90percent) yields and of 100percent ee.In contrast, the enzyme does not exhibit significant enantiomeric selectivity in its catalysis of oxidations of the corresponding racemic trans diols.The stereospecificities observed, or lack thereof, are as predicted by the active-site model.
