Regio- and Enantioselective Cyclization of Epoxy Alcohols Catalyzed by a [CoIII(salen)] Complex

Wu, Michael H.; Hansen, Karl B.; Jacobsen, Eric N.

doi:10.1002/(sici)1521-3773(19990712)38:13/14<2012::aid-anie2012>3.0.co;2-h

Cited by 117 publications

(54 citation statements)

References 3 publications

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“…In the case of substrates bearing 5 or 6 carbons, intramolecular addition of the alcohol to the epoxide occurred with high endo regioselectivity, in violation of Baldwin's rules, to afford the 6-or 7-membered ring ethers, respectively (Scheme 36). [101] Both recovered epoxide and cyclization product were produced in high ee. Instances of intramolecular kinetic resolutions such as these are unusual.…”

Section: Hydrolytic Kinetic Resolution Of Terminal Epoxides (Hkr)mentioning

confidence: 98%

Practical Considerations in Kinetic Resolution Reactions

2001

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This review provides a critical analysis of catalytic kinetic resolution reactions from a practical perspective, asking the question of when, if ever, is kinetic resolution the best option for the synthesis of an optically active target. A series of crucial conditions are identified, and it is postulated that if all of them are met, then indeed kinetic resolution can be highly practical. A variety of catalytic kinetic resolution processes are evaluated in the context of these criteria, with particular emphasis on catalyst availability, substrate scope, availability of the racemic substrate and of alternative methods for accessing enantiopure substrate or product, and key experimental considerations. It is found that several catalytic systems have been developed that offer almost unbeatable methods for the preparation of useful chiral building blocks.

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Section: Hydrolytic Kinetic Resolution Of Terminal Epoxides (Hkr)mentioning

confidence: 98%

Practical Considerations in Kinetic Resolution Reactions

2001

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“…The directing groups that promote endo cyclization via destabilization of the undesired spiro transition state include sulfones [21,34,35], as well as methoxymethyl substituents in combination with a lanthanide Lewis acid [22,[36][37][38] (Scheme 15.1b). Catalytic antibodies [39][40][41][42] and transition-metal complexes [43,44] can also be particularly effective in promoting endo cyclization by lowering the energies of fused transition states in certain cases. [18][19][20]; (b) enabled by deactivation of exo pathway [21,22].…”

Section: Control Of Regioselectivity In Intramolecular Epoxide-openinmentioning

confidence: 99%

Biomimetic Synthesis of Polyether Natural Products via Polyepoxide Opening

Vilotijević

Jamison

2011

Biomimetic Organic Synthesis

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“…Catalytic asymmetric COH bond insertion reactions have also found notable use in the formation of quaternary carbon stereocenters by desymmetrization, as exemplified in the synthesis of tetralone 36 (60,61). An additional useful method is illustrated by the formation of oxabicycloheptane 38 by intramolecular opening of prochiral epoxide 37 catalyzed by salen-Co complex 39 (62). Intramolecular Heck reactions have proven to be particularly useful in this approach to all-carbon quaternary centers (32,33).…”

Section: Desymmetrization Of Molecules Having Prochiral Quaternary Cementioning

confidence: 99%

Catalytic asymmetric synthesis of all-carbon quaternary stereocenters

Douglas

Overman

2004

Proc. Natl. Acad. Sci. U.S.A.

805

177

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Only a few catalytic asymmetric COC bond-forming reactions have been shown to be useful for constructing all-carbon quaternary stereocenters. This Perspective examines the current state of such methods.C arbon atoms bonded to four carbon substituents (all-carbon quaternary centers) pose a particular challenge for synthesis because creation of such centers is complicated by steric repulsion between the carbon substituents. When the four substituents differ, quaternary stereocenters become a singular challenge for achieving efficient asymmetric syntheses of chiral organic molecules (1-4). The invention of catalytic methods for asymmetric synthesis is one of the foremost recent achievements of chemistry (5), with the 2001 Nobel Prize in Chemistry recognizing William S. Knowles, Ryoji Noyori, and K. Barry Sharpless for their pioneering development of catalytic asymmetric hydrogenation and oxidation reactions. At present, many broadly useful methods for catalytic asymmetric oxidation and reduction exist; however, far fewer catalytic asymmetric methods for forming COC bonds have been invented to date (5). As disclosures in this special feature will attest, this latter area of catalytic asymmetric synthesis is a current focus of intense investigation worldwide.At present only a few catalytic asymmetric COC bond-forming reactions have been shown to be useful for constructing quaternary carbons, undoubtedly reflecting the additional steric challenge involved in forming all-carbon quaternary centers. This Perspective will examine the current state of such methods. The focus will be on reactions for which some generality has been documented, and several examples exist of reactions that proceed with enantiomeric selectivities of at least 9:1 [enantiomeric excesses (ees) Ͼ80%]. The discussion is organized by general reaction types that have proven useful, not by the more commonly used organizations that focus on one specific transformation or one family of asymmetric catalysts. It is hoped that this organization will highlight the many opportunities that exist for future discoveries in this area. The less general approach for forming allcarbon quaternary stereocenters in which a group-selective catalytic asymmetric reaction is used to desymmetrize a prochiral intermediate containing a quaternary carbon will be briefly mentioned also. No attempt to summarize this latter field will be made, as any catalytic asymmetric reaction could in principle be used in this approach. In four areas, catalytic methods for directly forming all-carbon stereocenters are most developed: Diels-Alder reactions, the combination of chiral carbon nucleophiles with carbon electrophiles, reactions of allylmetal intermediates with carbon nucleophiles, and intramolecular Heck reactions. Our discussion will begin with these reaction types. Asymmetric Diels-Alder ReactionsThe Diels-Alder reaction provides two approaches for forming quaternary stereocenters contained within the cyclohexene framework (Scheme 1). In reactions of type I, electron-rich dienes c...

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Regio- and Enantioselective Cyclization of Epoxy Alcohols Catalyzed by a [CoIII(salen)] Complex

Cited by 117 publications

References 3 publications

Practical Considerations in Kinetic Resolution Reactions

Practical Considerations in Kinetic Resolution Reactions

Biomimetic Synthesis of Polyether Natural Products via Polyepoxide Opening

Catalytic asymmetric synthesis of all-carbon quaternary stereocenters

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