Abstract:A range of 2-substituted-2,4-dimethyl-8-oxabicyclo[3.2.1]octan-3-ones 13-18 are available in four steps and in states of high optical purity. The fluoroketone 18 was shown to be a catalyst for the asymmetric epoxidation of stilbene, (E )-methylstilbene, phenylstilbene and chalcone (59-68% ee at 24-67% conversion) using Oxone ® as the primary oxidant.
“…Armstrong et al have made important contributions to the progress of this field, particularly, they rightly extolled the virtues of α-fluoro- N -ethoxycarbonyltropinone 96 as an efficient and readily recycled catalyst for the epoxidation of alkenes with Oxone (83% ee) . To improve the enantioselectivity further and to clarify the factors responsible for the asymmetric induction, many attempts to prepare bicyclo[3,2,1]octanone derivatives 95 and 97 with alternative α-substitution have been carried out. ,− Moreover, α-fluoroketone 98 displayed a much better ability to catalyze the asymmetric epoxidation of trans -stilbene with Oxone, for which enantiomerically enriched ketone 98 with 80% ee gave rise to stilbene epoxide with 74% ee. , …”
Section: 51 Simple Chiral Ketonesmentioning
confidence: 99%
“…239,[286][287][288][289][290][291][292][293][294][295] Moreover, R-fluoroketone 98 displayed a much better ability to catalyze the asymmetric epoxidation of trans-stilbene with Oxone, for which enantiomerically enriched ketone 98 with 80% ee gave rise to stilbene epoxide with 74% ee. 305,306…”
“…Armstrong et al have made important contributions to the progress of this field, particularly, they rightly extolled the virtues of α-fluoro- N -ethoxycarbonyltropinone 96 as an efficient and readily recycled catalyst for the epoxidation of alkenes with Oxone (83% ee) . To improve the enantioselectivity further and to clarify the factors responsible for the asymmetric induction, many attempts to prepare bicyclo[3,2,1]octanone derivatives 95 and 97 with alternative α-substitution have been carried out. ,− Moreover, α-fluoroketone 98 displayed a much better ability to catalyze the asymmetric epoxidation of trans -stilbene with Oxone, for which enantiomerically enriched ketone 98 with 80% ee gave rise to stilbene epoxide with 74% ee. , …”
Section: 51 Simple Chiral Ketonesmentioning
confidence: 99%
“…239,[286][287][288][289][290][291][292][293][294][295] Moreover, R-fluoroketone 98 displayed a much better ability to catalyze the asymmetric epoxidation of trans-stilbene with Oxone, for which enantiomerically enriched ketone 98 with 80% ee gave rise to stilbene epoxide with 74% ee. 305,306…”
“…A significant activating effect by a-fluorine substitution has been observed [2][3][4][5] and then extensively studied [6][7][8][9][10][11][12][13][14][15]. We have recently shown that, during epoxidation of methyl p-methoxycinnamate (Scheme 1), enantiopure tri-substituted cyclohexanones 1-3 were more efficient, leading to higher ee% and higher yields, when the halogen was axial (1a-3a) than when the halogen was equatorial (1e-3e) [7].…”
“…Targeted measurements have been collected to avoid decomposition reactions, and accident causes have become increasingly important. Buser , et al studied synthesizing and applying epoxiconazole with organic and inorganic peroxy acid, chlorohydrin, alkyl hydrogen peroxide, hydrogen peroxide, molecular oxygen, and other as oxidants to epoxidate triazolene into epoxiconazole. However, no research from around the world has yet to report on the thermal stabilities for said substances.…”
To clarify the thermal safety inherent in a new epoxiconazole crystal, differential scanning calorimetry (DSC) and adiabatic accelerating rate calorimetry (ARC) were used for testing and research. The Friedman method and model method were used to analyze thermal decomposition kinetics based on the DSC data, and the N-order and autocatalytic decomposition reaction kinetic models were established. The double scan method was utilized to verify the autocatalytic effect during the decomposition process. The Friedman method, N-order, and autocatalytic model methods were used to study the substance's thermal decomposition characteristics. ARC data are utilized to verify the aforementioned prediction results and the kinetic parameters that were obtained based on ARC data from N-order and autocatalytic model methods that concur with the simulation results. This paper applies the N-order and autocatalytic model to the kinetic model to further predict thermal safety parameter time to maximum rate under adiabatic conditions.
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