Ligand exchange reaction of sulfoxides in organic synthesis: A novel method for generation of magnesium enolates and its application to synthesis of [α]-halocarboxylic acid derivatives and [α]-haloaldehydes

Satoh, Tsuyoshi; Kitoh, Yasushi; Onda, Kenichi; Takano, Koji; Yamakawa, Kōji

doi:10.1016/s0040-4020(01)90408-9

Cited by 21 publications

(8 citation statements)

References 28 publications

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“…2‐chloropropionic ( 9 ), 2‐chlorobutanoic ( 10 ) and 2‐chloropentanoic ( 11 )] respectively. Our methodology offers clear advantages in terms of experimental simplicity and efficiency compared to a previous synthesis of 9 paved on a magnesium enolate formed from a α‐sulfinyl‐α‐chloro acid …”

Section: Methodsmentioning

confidence: 99%

“…Readily accessible benzyl-type sulfoxides served as excellent placeholders for the corresponding Mg carbenoids by simple treatment with CyMgCl for the appropriate metallation time (see SI) prior to CO 2 bubbling. [25] Rigidifying the sulfoxide core enabled the preparation of cyclopropyl-type magnesium carbenoids [26] which gave the corresponding haloacids 12-14 in uniformly high to excellent yields, again with better efficiency than reported strategies: for example, acid 12 was prepared in 14% with a chlorination protocol. The protocol showed a remarkable chemoselectivity, as noticed where potentially exchangeable halides could interfere (4).…”

mentioning

confidence: 99%

“…Our methodology offers clear advantages in terms of experimental simplicity and efficiency compared to a previous synthesis of 9 paved on a magnesium enolate formed from a a-sulfinyl-a-chloro acid. [25] Rigidifying the sulfoxide core enabled the preparation of cyclopropyl-type magnesium carbenoids [26] which gave the corresponding haloacids 12-14 in uniformly high to excellent yields, again with better efficiency than reported strategies: for example, acid 12 was prepared in 14% with a chlorination protocol. [27] Furthermore: 1) substitution across the cyclopropyl ring was perfectly tolerated; 2) the concomitant presence of a reactive ester (13) and an acid (14) were fully compatible with the reaction conditions.…”

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confidence: 99%

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A Straightforward Homologation of Carbon Dioxide with Magnesium Carbenoids en Route to α‐Halocarboxylic Acids

et al. 2019

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The homologation of carbon dioxide with stable, (enantiopure) magnesium carbenoids constitutes a valuable method for preparing a-halo acid derivatives. The tactic features a high level of chemocontrol, thus enabling the synthesis of variously functionalized analogues. The flexibility to generate magnesium carbenoids through sulfoxide-, halogen-or proton-Mg exchange accounts for the wide scope of the reaction.

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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A Straightforward Homologation of Carbon Dioxide with Magnesium Carbenoids en Route to α‐Halocarboxylic Acids

et al. 2019

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“…The configuration of alkene 4a was determined by comparison of its 1 H NMR spectrum with literature data. 10 Deprotection of acetals 3 with aqueous HCl (5%) in THF gave target a-chlorocinnamaldehydes 4 in good yields ( Table 1). The Z/E ratios of both 3 and 4 were determined by GC/MS.…”

Section: Methodsmentioning

confidence: 99%

“…5 Previously such compounds have been prepared using the Wittig approach, 6 HCl elimination from 2,3-dichloro-3-arylpropionaldehydes, 7 addition of 1-chloro-2,2-difluorovinyllithium to benzaldehyde, 8 chlorination of corresponding cinnamaldehydes 9 and thermal elimination of sulfinyl group from a-halo-a-sulfinylaldehydes. 10 We tried to use chloral as a polyhalogenated synthon in COR to prepare the corresponding a-chlorocinnamaldehydes. The hydrazone of 4-chlorobenzaldehyde was chosen as a model substrate.…”

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A New Synthetic Approach to α-Chlorocinnamaldehydes

et al. 2004

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A new simple and efficient transformation of aromatic aldehydes into a-chlorocinnamaldehydes is described. Catalytic olefination reaction of hydrazones of aromatic aldehydes with 2-trichloromethyl-1,3-dioxolane gives ethylene acetals of target alkenes in moderate to good yields. The reaction proceeds stereoselectively to form preferably Z-isomers.Olefination of carbonyl compounds, the R 1 R 2 C=O → R 1 R 2 C=CXY transformation, is one of the most successful synthetic routes to a variety of substituted alkenes. 1 In addition, many natural products possess various trisubstituted alkene moieties, and highly stereoselective construction of trisubstituted alkenes is one of the most challenging problems in synthetic organic chemistry. 2 Although many efficient and selective synthetic methods for the preparation of this important structural fragment have been devised for decades, there is still the need for a general and stereoselective method for an efficient synthesis of trisubstituted alkenes.Recently, we elaborated a novel approach to alkene synthesis, called catalytic olefination reaction (COR) of aldehydes and ketones. 3 It was found that N-unsubstituted hydrazones of carbonyl compounds could be smoothly converted to various substituted alkenes by treatment with polyhalogenoalkanes in the presence of catalytic amounts of CuCl. Based on COR we elaborated novel methods of synthesis of dichloroalkenes, dibromoalkenes, vinyl bromides, vinyl iodides, fluorine-containing alkenes, 1-chlorocinnamonitriles and 1-chlorocinnamates from aromatic and heteroaromatic carbonyl precursors. A possible mechanism of olefination was discussed and a catalytic cycle of COR was reported earlier. 4 This article is devoted to the synthesis of a-chlorocinnamaldehydes using catalytic olefination. a-Chlorocinnamaldehydes can be used as valuable building blocks for the synthesis of various heterocyclic systems. 5 Previously such compounds have been prepared using the Wittig approach, 6 HCl elimination from 2,3-dichloro-3-arylpropionaldehydes, 7 addition of 1-chloro-2,2-difluorovinyllithium to benzaldehyde, 8 chlorination of corresponding cinnamaldehydes 9 and thermal elimination of sulfinyl group from a-halo-a-sulfinylaldehydes. 10 We tried to use chloral as a polyhalogenated synthon in COR to prepare the corresponding a-chlorocinnamaldehydes. The hydrazone of 4-chlorobenzaldehyde was chosen as a model substrate. We have found that chloral could not be used as a reagent in COR because no formation of a-chlorocinnamaldehyde takes place. In the presence of chloral, the hydrazone is converted into corresponding sym-azine (according to GC/MS of reaction mixture). To modify the polyhalogenated synthon, we protected the chloral carbonyl group by transformation of chloral into 2-trichloromethyl-1,3-dioxolane. We started our investigation from optimization of reaction conditions because nature of solvent, base and amount of catalyst used in COR can influence the yield of product dramatically. Variation of bases (ammonia, ethylenediamine, triethylam...

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Preparation and Reactivity of Magnesium Enolates

Grison

2009

Patai's Chemistry of Functional Groups

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Ligand exchange reaction of sulfoxides in organic synthesis: A novel method for generation of magnesium enolates and its application to synthesis of [α]-halocarboxylic acid derivatives and [α]-haloaldehydes

Cited by 21 publications

References 28 publications

A Straightforward Homologation of Carbon Dioxide with Magnesium Carbenoids en Route to α‐Halocarboxylic Acids

A Straightforward Homologation of Carbon Dioxide with Magnesium Carbenoids en Route to α‐Halocarboxylic Acids

A New Synthetic Approach to α-Chlorocinnamaldehydes

Preparation and Reactivity of Magnesium Enolates

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