Remote stereocontrol by sulfinyl groups: asymmetric alkylation of chiral 2-p-tolylsulfinyl benzyl carbanions

Ruano, José Luis Garcı́a; Aranda, M. Teresa; Puente, Margarita

doi:10.1016/j.tet.2005.08.014

Cited by 16 publications

(9 citation statements)

References 39 publications

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“…2-p-Tolylsulfinyl benzyl carbanions [6] (derived from 1 by treatment with lithium diisopropylamide (LDA)) have shown a very high stereoselective nucleophilic behavior in their reactions with different electrophiles such as alkyl halides, [7] carbonyl compounds, [8] N-sulfinyl imines, [9] and N-aryl imines. [10] In all these reactions, chelated structures, with the counterion (Li + ) joined to the benzylic carbon and stabilized by the sulfinyl oxygen, have been postulated to account for the stereoselectivity [Scheme 1, Eq.…”

Section: Introductionmentioning

confidence: 99%

Stereodivergent Quaternization of 2‐Alkyl‐2‐p‐tolylsulfinylacetonitriles: NMR Spectroscopic Evidence of Planar and Pyramidal Benzylic Carbanions

Ruano

Martín-Castro

Tato

et al. 2010

Chemistry A European J

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Enantiomerically enriched alpha,alpha-disubstituted phenylacetonitriles have been readily prepared by stereoselective quaternization of 2-alkyl-2-[2-(p-tolylsulfinyl)phenyl]acetonitriles with different alkylating electrophiles in the presence of bases. The use of potassium hexamethyldisilazane (KHMDS)/[18]crown-6 ether and NHMDS with alkyl halides afforded S,S(S) and R,S(S) diastereoisomers, respectively, in high enantiomeric purities, thus providing stereodivergent processes for synthesizing both isomers. The dependence of the stereochemical course of the reactions on the experimental conditions (mainly on the counterion) has been rationalized by assuming a planar or pyramidal structure for the benzylic carbanions. This hypothesis has been supported by NMR spectroscopic studies, which permit one to assign a chelated pyramidal structure to the sodium benzylic carbanions and an almost planar naked carbanionic structure to the potassium benzylic carbanions generated in the presence of [18]crown-6 ether.

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Section: Introductionmentioning

confidence: 99%

Stereodivergent Quaternization of 2‐Alkyl‐2‐p‐tolylsulfinylacetonitriles: NMR Spectroscopic Evidence of Planar and Pyramidal Benzylic Carbanions

Ruano

Martín-Castro

Tato

et al. 2010

Chemistry A European J

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“…Due to the successful results obtained in the literature using sulfoxides as chiral auxiliaries in directed lithiationdiastereoselective trapping sequences on aromatic compounds, [25][26][27][28][29][30][31][32][33][34] as well as in our precedent work, [35][36][37][38][39][40] and due to the robustness of the tert-butyl sulfinyl group, we chose the latter as the stereoinducer in our targeted transformation. † Dedicated to Professor Ei-ichi Negishi for his 80th birthday.…”

Section: Resultsmentioning

confidence: 99%

Atroposelective synthesis of axially chiral P,S-ligands based on arynes

et al. 2015

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The first atropo-selective aryl-aryl coupling based on arynes in the presence of a tert-butylsulfinyl group as the chiral auxiliary on the aryllithium nucleophile is described. The approach allows for the efficient access to a novel family of atropo-enantiopure biphenyl-based phosphine-thioether ligands. The new P,S heterodonor ligands were assessed in model palladium-catalyzed allylic substitution reactions.

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“…They were satisfactory only with highly reactive halides. Benzyl and allyl halides afforded mixtures of diastereoisomers with up to 90% de's [14]. Methyl and ethyl halides or triflates also provided good de's.…”

Section: Methodsmentioning

confidence: 99%

Stereocontrolled reactions mediated by remote sulfoxides: Formation and reactivity of enantiomerically pure benzylic centers

Ruano

Castro

2007

Heteroatom Chemistry

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Reactions of different electrophiles (alkyl halides, aldehydes, N-sulfinylimines, imines, etc) with (S)-2-p-toluenesulfinyl toluene and their alkyl, triisopropylsilyloxy, and methylthio derivatives at benzylic position, in the presence of LDA, allow the synthesis of a variety of enantiomerically pure benzylic centers, whose configuration is efficiently controlled by the γ -sulfinyl group, according to 1,4-asymmetric induction processes. With prochiral electrophiles, the 1,5-asymmetric induction processes can also be controlled either by modifying their steric or electronic features or by incorporating an additional chiral center at the electrophiles. C 2007 Wiley Periodicals, Inc.

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Remote stereocontrol by sulfinyl groups: asymmetric alkylation of chiral 2-p-tolylsulfinyl benzyl carbanions

Cited by 16 publications

References 39 publications

Stereodivergent Quaternization of 2‐Alkyl‐2‐p‐tolylsulfinylacetonitriles: NMR Spectroscopic Evidence of Planar and Pyramidal Benzylic Carbanions

Stereodivergent Quaternization of 2‐Alkyl‐2‐p‐tolylsulfinylacetonitriles: NMR Spectroscopic Evidence of Planar and Pyramidal Benzylic Carbanions

Atroposelective synthesis of axially chiral P,S-ligands based on arynes

Stereocontrolled reactions mediated by remote sulfoxides: Formation and reactivity of enantiomerically pure benzylic centers

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