Titanium–Salan‐Catalyzed Asymmetric Epoxidation with Aqueous Hydrogen Peroxide as the Oxidant

Sawada, Yuji; Matsumoto, Kazuhiro; Kondo, Shozo; Watanabe, Hisayuki; Ozawa, Tomoyuki; Suzuki, Kenji; Saito, Bunnai; Katsuki, Tsutomu

doi:10.1002/anie.200600636

Cited by 167 publications

(59 citation statements)

References 28 publications

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“…Solche Reaktionen zeigen Potenzial für großtechnische Oxidationsprozesse,f ür die unkritische Ansätze gebraucht werden. [194] Bisher sind die so genannten Ti-Salalen-Komplexe [195] die enantioselektivsten Oxidationskatalysatoren. Ein besonderer Bereich der Forschung kçnnte daher die Verringerung der Komplexität des ursprünglichen Katalysators hin zu einfacheren Motiven sein, die bereits die gleiche oder eine bessere Leistung als der komplexe Ausgangskatalysator gezeigt haben.…”

Section: London'sche Dispersionunclassified

London’sche Dispersionswechselwirkungen in der Molekülchemie – eine Neubetrachtung sterischer Effekte

2015

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Die London’sche Dispersion, die den attraktiven Teil des Van‐der‐Waals‐Potentials beschreibt, wurde lange als Element struktureller Stabilität in der molekularen Chemie unterschätzt. Als solches beeinflusst sie auch entscheidend die chemische Reaktivität und Katalyse. Ihre Vernachlässigung ist auf die Annahme zurückzuführen, dass die Dispersionswechselwirkung schwach sei, was nur für eine einzelne paarweise Wechselwirkung zweier Atome stimmt. Für Strukturen zunehmender Größe kann die gesamte Dispersionsstabilisierung mehrere zehn kcal mol−1 betragen. Dieser Aufsatz soll die Wichtigkeit inter‐ und intramolekularer Dispersion anhand von Beispielen für die erste Vollperiode verdeutlichen. Die Synergie aus Experiment und Theorie hat ein Niveau erreicht, auf dem Dispersionseffekte sehr genau verstanden werden können. Als Konsequenz daraus werden wir wohl unser Verständnis bezüglich sterischer Hinderung und stereoelektronischer Effekte überdenken müssen. Die Quantifizierung von Dispersionsenergiedonoren wird unsere Fähigkeiten verbessern, komplexe molekulare Strukturen und Katalysatoren zu entwickeln.

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Section: London'sche Dispersionunclassified

London’sche Dispersionswechselwirkungen in der Molekülchemie – eine Neubetrachtung sterischer Effekte

2015

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“…However, recently the groupof Katsuki reported on a significant breakthrough in the field of titanium-catalyzed asymmetric epoxidation of nonfunctionalized alkenes [11][12][13]. The successful catalysts used in this system are based on a combination of titanium and reduced salen-type ligands (also known as salenan and salan, respectively).…”

Section: Epoxidations Of Alkenes Catalyzed By Early Transition Metalsmentioning

confidence: 99%

“…Hence, the chemoselectivity could to a certain point be controlled by the choice of additive. Ribas and Costas have studied manganese triflate complexes based on the 2-pyridyl derivative of TACN (12), and they found that complex 13 was a robust and active catalyst for the epoxidation of alkenes using peracetic acid as the terminal oxidant [53]. More recently, this catalyst was found to be compatible with aqueous hydrogen peroxide if the epoxidation reactions were performed with acetic acid (14 equiv.)…”

Section: Manganese-catalyzed Epoxidationsmentioning

confidence: 99%

Transition Metal‐Catalyzed Epoxidation of Alkenes

Adolfsson

2010

Modern Oxidation Methods

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“…On the basis of the hypothesis that a peroxotitanium complex 20 (Fig. 11.2 ), in which the amino proton of the ligand forms hydrogen bond with the peroxo ligand, is the active species for the reaction, the authors further explored titanium -based epoxidation catalysts and found that titanium (salan) complexes 21 promote the asymmetric olefi n epoxidation (Scheme 11.25 ) [39] . A brief screening of salan ligands disclosed that complex 21d bearing cyclohexanediamine moiety and phenyl groups at the C3 and C3 ′ positions exhibited high asymmetric catalysis.…”

Section: Titanium Catalystmentioning

confidence: 99%

Asymmetric Oxidations and Related Reactions

Matsumoto

Katsuki

2010

Catalytic Asymmetric Synthesis

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GENERAL INTRODUCTIONOxidation is a fundamental technology for converting bulk chemicals into valuable materials and is also a useful tool for sophisticated functionalization of organic molecules. Thus, intensive research efforts have been devoted to the development of selective and practical oxidation methods, and a wide variety of chiral metal -based catalysts and organocatalysts have been developed for catalytic asymmetric oxidation reactions in industry and academia in the last half -century [1] . In contrast to the rapid improvement in stereoselectivity, the enhancement of atom economy [2] falls behind. While atom effi ciency (especially active oxygen content in oxygenation reactions) of stoichiometric oxidants is a factor that should be considered, most of the catalytic asymmetric oxidations still use conventional stoichiometric oxidants of low atomeffi ciency such as peracids, alkyl hydroperoxides, hypervalent iodine reagents, hypochlorite, and N -oxide compounds (Table 11.1 ). The use of such oxidants causes the formation of large amounts of undesirable waste. From the viewpoint of ecological sustainability, oxidation with a higher atom -effi cient, safe, abundant, and preferably inexpensive oxidant is favorable. Considering the requirements, molecular oxygen and hydrogen peroxide are the oxidants of choice [3] . Molecular oxygen offers a large advantage because it is abundant in air and is inexpensive. Aerobic oxidation that directly uses ambient air as an oxidant is similar to respiration in living organisms. Hydrogen peroxide is also recognized as a green oxidant. It is almost as equally atomeffi cient as molecular oxygen, and the by -product is safe and clean water. Moreover, its aqueous solution (typically 30 -35%) is inexpensive and easy to handle. Consequently, the development of catalytic asymmetric oxidations with molecular oxygen Catalytic Asymmetric Synthesis, Third Edition, Edited by Iwao Ojima

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Titanium–Salan‐Catalyzed Asymmetric Epoxidation with Aqueous Hydrogen Peroxide as the Oxidant

Cited by 167 publications

References 28 publications

London’sche Dispersionswechselwirkungen in der Molekülchemie – eine Neubetrachtung sterischer Effekte

London’sche Dispersionswechselwirkungen in der Molekülchemie – eine Neubetrachtung sterischer Effekte

Transition Metal‐Catalyzed Epoxidation of Alkenes

Asymmetric Oxidations and Related Reactions

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