Methoden der asymmetrischen Synthese – enantioselektive katalytische Hydrierung

Izumi, Yoshiharu

doi:10.1002/ange.19710832303

Cited by 61 publications

(7 citation statements)

References 41 publications

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“…In general, enantioselective synthesis implies the preferential formation of one enantiomer of the product from achiral reagents, usually in the presence of a chiral catalyst. [40] This synthetic approach has clear advantages and has recently been applied to the enantioselective Strecker [41] MCR with zirconium alkoxides as catalysts in the presence of molecular sieves (Scheme 5). The chemical yield was excellent and the enantioselectivity high; the results were independent of the nature of the aldehyde (aromatic or aliphatic, including primary, secondary, and tertiary) and of the reaction scale, [42] thus allowing the enantioselective synthesis of pipecolic acid.…”

Section: Enantioselective Approachmentioning

confidence: 99%

Asymmetric Multicomponent Reactions (AMCRs): The New Frontier

2005

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Asymmetric multicomponent reactions involve the preparation of chiral compounds by the reaction of three or more reagents added simultaneously. This kind of addition and reaction has some advantages over classic divergent reaction strategies, such as lower costs, time, and energy, as well as environmentally friendlier aspects. All these advantages, together with the high level of stereoselectivity attained in some of these reactions, will force chemists in industry as in academia to adopt this new strategy of synthesis, or at least to consider it as a viable option. The positive aspects as well as the drawbacks of this strategy are discussed in this Review.

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Section: Enantioselective Approachmentioning

confidence: 99%

Asymmetric Multicomponent Reactions (AMCRs): The New Frontier

2005

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“…2). The precise pathway of the reaction and the mechanism of this enantioselective control, however, have not been verified yet though several models of the modified surface have been proposed to interpret the activity.…”

Section: )-(+)--Mhb (R)-(-)-mhbmentioning

confidence: 99%

Mechanism of Enantioface Differentiating Hydrogenation on Modified Nickel Surfaces

Yasumori¹

1979

Chemistry for the Welfare of Mankind

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-Recent studies on the mechanism of enantioface differentiation are described for the hydrogenation of methyl acetoacetate (MAA) over nickel surfaces modified with optically active molecules. Detailed investigations of the reaction using MAA vapor and tartaric acid as a modifier prove that the differentiation is controlled by the oriented adsorption of MAA which is caused by the attractive interaction between MAA and the modifier molecules. The influence of the conditions of reaction and the added poisons on the asymmetric yield is discussed on the basis of the proposed mechanism.

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“…This principle, which has been the subject of various recent reports [123][124][125][126], has been exploited to a remarkable degree by the Hoffmann-LaRoche group in the synthesis of several racemic and optically active steroid and 19-norsteroid derivatives. It may be briefly defined as the generation, with some degree of configurational specificity, of a new asymmetric center during the course of a chemical reaction.…”

Section: Asymmetric Inductionmentioning

confidence: 99%

Cd → BCD → Abcd

1974

Organic Chemistry: A Series of Monographs

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The starting CD intermediates for the various total syntheses outlined in this chapter and in Chapter 7 are often the same or quite analogous. Historically, a large effort has been expended in the preparation of such material, both in the context of steroid synthesis and, recently, as a goal unto itself. A discussion of the pathways developed for the synthesis of CD intermediates has been included at this point such that later, when the individual total synthetic schemes are presented, it will be unnecessary to outline the preparation of the starting materials, except in those cases where unique pathways have been developed.Most of the early synthetic plans started with appropriate naphthalene derivatives which in turn gave rise to D-homosteroids. For example, Johnson's estrone synthesis started with decalin-l,5-dione (3, Scheme 12-1) which had earlier been prepared from 1,5-dihydroxynaphthalene (58%) [1], By modifying the previously employed conditions to include Raney nickel hydrogénation at elevated temperatures and pressures in a basic ethanolic solution, it was possible to obtain a mixture of diols, 2 (stereochemistry undetermined), which, without purification, could be oxidized to a mixture of eis and trans diketones 3 [2], The yield for this conversion (l-»3) was 55% and, for synthetic purposes, the mixture 239 O OH J Φ-,ύ^.

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Methoden der asymmetrischen Synthese – enantioselektive katalytische Hydrierung

Cited by 61 publications

References 41 publications

Asymmetric Multicomponent Reactions (AMCRs): The New Frontier

Asymmetric Multicomponent Reactions (AMCRs): The New Frontier

Mechanism of Enantioface Differentiating Hydrogenation on Modified Nickel Surfaces

Cd → BCD → Abcd

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