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Studies in enantioselective oxygen a...

Palucki, Michael.

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Studies in enantioselective oxygen atom transfer catalyzed by (salen) manganese(III) complexes.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Studies in enantioselective oxygen atom transfer catalyzed by (salen) manganese(III) complexes./
作者:	Palucki, Michael.
面頁冊數:	192 p.
附註:	Adviser: Eric N. Jacobsen.
Contained By:	Dissertation Abstracts International57-02B.
標題:	Chemistry, Inorganic. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9619541

Studies in enantioselective oxygen atom transfer catalyzed by (salen) manganese(III) complexes.
Palucki, Michael.

Studies in enantioselective oxygen atom transfer catalyzed by (salen) manganese(III) complexes. - 192 p.

Adviser: Eric N. Jacobsen.

Thesis (Ph.D.)--Harvard University, 1996.

A new, low temperature method has been developed for Mn(salen)-catalyzed asymmetric olefin epoxidation using the combination of m-CPBA/NMO. This protocol has allowed the attainment of good enantioselectivity (up to 86% ee) for terminal olefins, for the first time. Isotopic labelling studies has permitted an assessment of the relative contribution of the facial selectivity in the first C-O bond forming step and the diastereoselectivity for the ring closure in the second C-O bond forming step. Improved enantioselectivities at low temperatures are the result of enhanced selectivities in each of the C-O bond forming steps.Subjects--Topical Terms:

517253
Chemistry, Inorganic.

Studies in enantioselective oxygen atom transfer catalyzed by (salen) manganese(III) complexes.
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035 $a (UnM)AAI9619541
035 $a AAI9619541
040 $a UnM $c UnM
100 1 $a Palucki, Michael. $3 1257236
245 1 0 $a Studies in enantioselective oxygen atom transfer catalyzed by (salen) manganese(III) complexes.
300 $a 192 p.
500 $a Adviser: Eric N. Jacobsen.
500 $a Source: Dissertation Abstracts International, Volume: 57-02, Section: B, page: 1090.
502 $a Thesis (Ph.D.)--Harvard University, 1996.
520 $a A new, low temperature method has been developed for Mn(salen)-catalyzed asymmetric olefin epoxidation using the combination of m-CPBA/NMO. This protocol has allowed the attainment of good enantioselectivity (up to 86% ee) for terminal olefins, for the first time. Isotopic labelling studies has permitted an assessment of the relative contribution of the facial selectivity in the first C-O bond forming step and the diastereoselectivity for the ring closure in the second C-O bond forming step. Improved enantioselectivities at low temperatures are the result of enhanced selectivities in each of the C-O bond forming steps.
520 $a The addition of N-oxides to Mn(salen) epoxidations had a strong influence on the rate of the reaction, enantioselectivities, and cis/trans selectivities. A wide range of enantioselectivities was obtained with various oxidants in the absence of N-oxides, whereas similar enantioselectivities were observed in the presence of N-oxides. This result, coupled kinetic experiments indicate that a common Mn oxo intermediate is responsible for the high enantioselectivity pathway in epoxidation reactions.
520 $a The degree of asymmetric induction in the Mn(salen)-catalyzed epoxidation reaction was found to correlate with the electronic character of the catalyst, with catalysts containing electron donating substituents affording higher enantioselectivities than catalysts containing electron withdrawing substituents. Analysis of inverse isotope effects in epoxidations of cis-$\beta$-deuteriostyrene revealed that electron rich catalysts effect epoxidation through later transition states than do electron poor catalysts. Studies conducted over a wide reaction temperature range revealed that $\Delta\Delta $h $\ddagger$ for olefin epoxidation correlates directly with the electronic character of the catalyst. Taken together, these results suggest that catalyst electronic effects can be rationalized according to a Hammond Postulate argument wherein high enantioselectivity is maximized in a product-like transition state.
520 $a Finally, chiral (salen)Mn(III) complexes were found to be effective catalysts for the enantioselective oxidation of prochiral sulfides. Various oxidants were found to be capable of oxygen atom transfer, with H$\sb2 $o $\sb2$ emerging as the oxidant of choice. A variety of sulfides were oxidized with moderate ee (up to 68%).
590 $a School code: 0084.
650 4 $a Chemistry, Inorganic. $3 517253
650 4 $a Chemistry, Organic. $3 516206
690 $a 0488
690 $a 0490
710 2 0 $a Harvard University. $3 528741
773 0 $t Dissertation Abstracts International $g 57-02B.
790 $a 0084
790 1 0 $a Jacobsen, Eric N., $e advisor
791 $a Ph.D.
792 $a 1996
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9619541