The first example for the asymmetric synthesis of allenes by the Doering–LaFlamme allene synthesis with enantiopure cyclopropylmagnesium carbenoids

Momochi, Hitoshi; Noguchi, Takafumi; Miyagawa, Toshifumi; Ogawa, Naoki; Tadokoro, Makoto; Satoh, Tsuyoshi

doi:10.1016/j.tetlet.2011.03.150

Cited by 11 publications

(4 citation statements)

References 35 publications

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“…Dichloro( p ‐tolylsulfinyl)methylpotassium having an electropositive potassium cation is more likely to undergo the elimination than dichloro( p ‐tolylsulfinyl)methyllithium. Therefore, lithium amides are suitable for the generation of anionic species of aryl dichloromethyl sulfoxides in asymmetric synthesis . In the previous study, we proposed a chlorine‐assisted pyramidal inversion mechanism .…”

Section: Resultsmentioning

confidence: 99%

“…Recently, we established an efficient method for the optical resolution of racemic aryl dichloromethyl sulfoxides 1 utilizing (–)‐menthone as a resolving agent . In the course of our study on the synthetic applications of the sulfoxides 1 , we encountered the facile racemization of the sulfoxides 1 under basic reaction conditions ; however, in general, the S ‐chiral sulfoxides do not readily racemize . Herein, we report an experimental and theoretical study on the configurational stability and racemization mechanism of optically active aryl dichloromethyl sulfoxides.…”

Section: Introductionmentioning

confidence: 99%

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Configurational Stability of Optically Active Dichloromethyl p‐Tolyl Sulfoxide and Its Anionic Species: Experimental and Theoretical Study

Kimura

Tsuru

Momochi

et al. 2013

Heteroatom Chemistry

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Racemization of optically active dichloromethyl p-tolyl sulfoxide took place at −78 • C in the presence of potassium bis(trimethylsilyl)amide (KHMDS), while the same racemization did not occur under reflux in toluene in the absence of KHMDS. Density functional theory calculations suggested that the pyramidal inversion at the sulfur center was unlikely to be involved in the racemization mechanism. An anionic species of the sulfoxide was found to be gradually converted into chlorobis(p-tolylsulfinyl)methane and dichlorocarbene. We propose a racemization mechanism mediated by achiral potassium p-toluenesulfenate and chloro(p-tolylsulfinyl)methylene. C 2013 Wiley Periodicals, Inc. Heteroatom Chem 24:131-137, 2013; View this article online at wileyonlinelibrary.com.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Configurational Stability of Optically Active Dichloromethyl p‐Tolyl Sulfoxide and Its Anionic Species: Experimental and Theoretical Study

Kimura

Tsuru

Momochi

et al. 2013

Heteroatom Chemistry

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“…Satoh and coworkers [53] have reported the formation of cyclopropanes by addition of lithium dichloromethyl α-sulfinyl carbanions to α,β-unsaturated carbonyl compounds (1,4-addition and chlorine substitution) with excellent enantiomeric…”

Section: Alkyl Carbanionsmentioning

confidence: 99%

Sulfur‐Bearing Lithium Compounds in Modern Synthesis

Ruano

Parra

Alemán

2014

Lithium Compounds in Organic Synthesis

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Sulfur functions have been widely used for the stabilization of lithium carbanions. Their different oxidation states determine a variety of mechanisms for such stabilization, mainly related with their electronic effects (−I and −M) and associative abilities and also with the relative position of sulfur with respect to the C-Li bond. As additional interest, the sulfur of some of these functions is a stable stereogenic center, and their interactions with prochiral lithium carbanions are able to control the stereochemical course of their reactions with electrophiles, which can be successfully used in asymmetric synthesis. Finally, the chemical versatility of the sulfur functions and their easy elimination under diverse conditions confer to the sulfur-stabilized lithium carbanions a very important role in modern synthetic chemistry. In this chapter, we have organized the information attending to the relative position of the carbanionic center with respect to the sulfur function (α-, β-, and γ-lithiation, see Figure 8.1). Each item has been subdivided according to the nature of the sulfur function stabilizing the carbanion. In this sense, sulfoxides, sulfones, and sulfoximines are the three main functions stabilizing any type of lithium-carbanions, but the thioethers have also been described as stabilizing in αand β-lithiation processes. The fragment connecting S and Li is always formed by carbon atoms, but N is present in some cases of γ-lithiation.This chapter covers the literature of the last 10-12 years concerning the preparation and main synthetic applications of the lithium carbanions stabilized by sulfur functions. In most of the cases, the information that appeared in this century helps understand the role of the sulfur functions in the stabilization of the lithium carbanions, and therefore we have only mentioned, as introduction, the seminal references in the field. However, in those cases where there are few references in the last decade and most of the information has been reported before 2000, we have included and briefly commented on the most significant contributions to be able to understand the interest of such stabilizing functions. During the last decade have appeared excellent revisions concerning the reactivity and structure of lithium carbanions [1], the use of different sulfur functions in asymmetric synthesis [2], as Lithium Compounds in Organic Synthesis: From Fundamentals to Applications, First Edition. Edited by Renzo Luisi and Vito Capriati.

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“…This procedure was extended to an asymmetric synthesis of -allenic alcohols (Scheme 16). 31 The reaction of ,-unsaturated ester 112 with enantiopure (R)-dichloromethyl p-tolyl sulfoxide 32 was carried out with LiHMDS to give cyclopropane 113 in high optical yield with moderate chemical yield. The ester group was reduced to a hydroxymethyl group to afford alcohol 114.…”

Section: -4 Doering-laflamme-type Rearrangementmentioning

confidence: 99%

Recent Advances in the Chemistry and Synthetic Uses of Magnesium Carbenoids

Satoh¹

2012

HETEROCYCLES

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Carbenes and carbenoids have long been recognized to be a highly reactive species and are frequently used as intermediates in organic synthesis.However, most of the carbenes and carbenoids are relatively short-lived and are too reactive to control. Recently, the author's group found that the treatment of aryl -chloroalkyl sulfoxides and -chlorovinyl p-tolyl sulfoxides with a Grignard reagent at low temperature gave magnesium carbenoids via the sulfoxide-magnesium exchange reaction. Magnesium carbenoids, cyclopropylmagnesium carbenoids, cyclobutylmagnesium carbenoids, magnesium alkylidene carbenoids, and magnesium -oxido carbenoids were generated from the corresponding -chloro sulfoxides with a Grignard reagent at low temperature.The generated magnesium carbenoids were proved to be relatively stable and they showed very interesting reactivity with several nucleophiles to afford many unprecedented new reactions. The present review is written for the purpose of reflecting recent achievements in the areas of chemistry and synthetic application of above-mentioned magnesium carbenoids. This review mainly covers literature from 2006 to late 2011. CONTENTS1.

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The first example for the asymmetric synthesis of allenes by the Doering–LaFlamme allene synthesis with enantiopure cyclopropylmagnesium carbenoids

Cited by 11 publications

References 35 publications

Configurational Stability of Optically Active Dichloromethyl p‐Tolyl Sulfoxide and Its Anionic Species: Experimental and Theoretical Study

Configurational Stability of Optically Active Dichloromethyl p‐Tolyl Sulfoxide and Its Anionic Species: Experimental and Theoretical Study

Sulfur‐Bearing Lithium Compounds in Modern Synthesis

Recent Advances in the Chemistry and Synthetic Uses of Magnesium Carbenoids

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