Asymmetric [2,3]wittig Sigmatropic Rearrangements Involving Chiral Amide Enolates as the Migrating Termini

Mikami, Kōichi; Takahashi, Osamu; Kasuga, Takashi; Nakai, Takeshi

doi:10.1246/cl.1985.1729

Cited by 30 publications

(13 citation statements)

References 7 publications

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“…146,[156][157][158][159][160][161][162][163] Complete retention of enolate geometry accompanies the metal exchange. 156,157 Both (E)-and (Z)-zirconium enolates have been shown to undergo selective kinetic aldol condensation to give mainly syn/erythro products (Scheme 44).…”

Section: Zirconium Enolatesmentioning

confidence: 99%

2.06 Formation of Enolates

Mekelburger

Wilcox

2014

Comprehensive Organic Synthesis II

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Section: Zirconium Enolatesmentioning

confidence: 99%

2.06 Formation of Enolates

Mekelburger

Wilcox

2014

Comprehensive Organic Synthesis II

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“…The first enantioselective [2,3] sigmatropic rearrangement of acyclic diprop-2-ynyl ethers and alkenyl benzyl ethers is achieved by a BuLi-chiral ligand complex.…”

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“…The [2,3] sigmatropic rearrangement has been studied with regard to its stereochemical course in view of its synthetic application to the preparation of highly functionalized derivatives. 1 Asymmetric [2,3] sigmatropic rearrangement involving chiral auxiliaries has been investigated by Nakai and coworkers and Enders and co-workers in order to achieve high diasteroselectivity. 2 However, the enantioselective version of this reaction has remained one of the unsolved problems in the field of synthetic organic chemistry.…”

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confidence: 99%

“…1 Asymmetric [2,3] sigmatropic rearrangement involving chiral auxiliaries has been investigated by Nakai and coworkers and Enders and co-workers in order to achieve high diasteroselectivity. 2 However, the enantioselective version of this reaction has remained one of the unsolved problems in the field of synthetic organic chemistry. Marshall and Lebreton reported the first example of this reaction, in which a 13-membered cyclic ether afforded the prop-2-ynylic alcohol in 70% ee by the use of a chiral lithium amide.…”

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confidence: 99%

“…3,4 Fujimoto and Nakai demonstrated an enantioselective reaction for acyclic substrates via a boron ester enolate. 5 Gladysz and co-workers reported the enantioselective [2,3] sigmatropic rearrangement of sulfur ylides using a chiral rhenium complex. 6 However, no examples of an enantioselective reaction of acyclic substrates involving an sp 3 carbanion, which are the most typical substrates in this rearrangement, have been demonstrated so far.…”

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Enantioselective [2,3] sigmatropic rearrangement mediated by a butyllithium–chiral ligand complex

Manabe¹

1997

Chem. Commun.

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The [2,3]‐Wittig Rearrangement

Nakai

Mikami

1994

Organic Reactions

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The [2,3]‐sigmatropic rearrangement, constitutes a versatile type of bond reorganization which encompasses a number of variations in terms of an atom pair (X, Y) and the type of electron pair on Y (anions, nonbonding electron pairs, or ylides). The Sommelet–Hauser rearrangement is representative. This chapter focuses on the special class of [2,3]‐sigmatropic rearrangement that involves an oxycarbanion (X = oxygen, Y = carbanion) as the migrating terminus. This type of rearrangement is now termed the [2,3]‐Wittig (sigmatropic) rearrangement. The reaction name clearly originates from the fact that this rearrangement formally represents a [2,3]‐sigmatropic version of the classic Wittig rearrangement, a well‐known 1,2‐alkyl shift of oxycarbanions. The [2,3]‐Wittig rearrangement has a rather recent history. Perhaps the first observation of the [2,3]‐Wittig shift is the rearrangement of the allyl fluorenyl ether, which was made in 1960 in the context of mechanistic studies on the Wittig rearrangement. The period of the 1960s to the early 1970s witnessed slow progress with a focus on mechanistic studies mainly of allyl benzyl ether systems. The synthetic power of this carbanion rearrangement as a general method was recognized when Still (1978) and Nakai (1981) established the highly stereoselective variants of the genuine [2,3]‐Wittig rearrangement. In recent years the [2,3]‐Wittig rearrangement has enjoyed widespread application in many facets of organic synthesis. Various aspects of the reaction have been reviewed. This chapter deals with the mechanism, scope and limitation, stereochemistry, and synthetic applications of the [2,3]‐Wittig rearrangement with emphasis on the stereochemical aspects and the synthetic utility. Other hetero [2,3]‐Wittig rearrangements such as thio‐[2,3]‐Wittig variants are not covered.

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Asymmetric [2,3]wittig Sigmatropic Rearrangements Involving Chiral Amide Enolates as the Migrating Termini

Cited by 30 publications

References 7 publications

2.06 Formation of Enolates

2.06 Formation of Enolates

Enantioselective [2,3] sigmatropic rearrangement mediated by a butyllithium–chiral ligand complex

The [2,3]‐Wittig Rearrangement

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