Enantioselective dialkylation of 1,2-phthalicdicarboxaldehyde

Kleijn, H.; Jastrzebski, Johann T. B. H.; Boersma, J.; Koten, Gerard van

doi:10.1016/s0040-4039(01)00586-x

Cited by 9 publications

(2 citation statements)

References 12 publications

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“…Our decision to pursue these investigations was for the following reasons: (i) The starting thiol 2 is reported to be readily available from enantiopure (α)-phenylethylamine, which is an inexpensive chiral amine sold as either enantiomer. (ii) Dialkylaminoethyl groups are known 9 to be efficient chiral auxiliaries.…”

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confidence: 99%

Novel Approach to the Synthesis of Enantioenriched Sulfoxides. Highly Diastereoselective Alkylation of Sulfenate Anions with 1,4-Asymmetric Induction

2002

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[reaction: see text] Efficient 1,4-asymmetric induction with an enantiopure aminoalkyl group as the chiral auxiliary has been achieved in the first example of diastereoselective alkylation (up to 98:2) of a sulfenate anion, readily prepared by oxidation of the corresponding thiolate. The stereochemistry of the sulfoxide produced is the opposite of that obtained by the conventional route based on oxidation of the sulfide precursor.

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Novel Approach to the Synthesis of Enantioenriched Sulfoxides. Highly Diastereoselective Alkylation of Sulfenate Anions with 1,4-Asymmetric Induction

2002

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“…Reaction in that case may be terminated after the first alkyl addition step by cyclization through a favorable 5-ring transition state, and the resulting hemiacetal may either be isolated or reacted further. [18] The observation of metalated hemiacetals in organometallic reactions is otherwise rare, [19] with a single X-ray characterization. [20] Hemiacetal intermediates have been implicated in catalysis, particularly in the Baylis-Hillman reaction.…”

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Observation of a Transient Intermediate in Soai’s Asymmetric Autocatalysis: Insights from ¹H NMR Turnover in Real Time

et al. 2012

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The amplifying asymmetric autocatalysis of alkylzinc addition to aldehydes discovered by Soai and co-workers in 1995 remains the only effective example of this genre, [1,2] despite widespread continuing interest in asymmetric amplification, primarily in the context of studies probing the origin of biological homochirality.[3] The autocatalytic process is highly circumscribed, being effective only within a narrowly defined regime: only 2-substituted pyrimidin-5-als such as 1 function as reactant [4] and only di-isopropylzinc 2 functions as reagent. The active catalyst is thought to be a higher-order alkoxide species derived from alkoxide 3 and is normally generated in situ from the alcohol 4. Significant advances in the period since the initial discovery include absolute asymmetric synthesis, [5,6] amplification from extremely low to high levels of enantiomer excess, [7] and initiation by diverse chiral entities or by isotopically chiral promoters. [8,9] Kinetic and spectroscopic studies have provided much information about the nature of the autocatalytic process, and kinetic and computational modeling have contributed to our understanding. To date, however, neither experimental observations of intermediate species, nor evidence of the nature of the catalytic entity, have been reported. Hence the molecular mechanisms by which amplifying autocatalysis occur are not yet properly understood.We report the direct observation of active species during catalytic turnover in the Soai autocatalytic Zn alkylation by 1 H NMR spectroscopy. This work confirms the surprising dependence on reaction temperature reported previously and reveals the first temporal observation of an intermediate species present during the reaction, which is transient at 0 8C but stable below À20 8C. The species is observed from the onset of the accelerating phase of autocatalytic turnover. Our earlier kinetic work indicated an equilibrating reaction product, formed without selectivity between homo-and heterochiral dimers, for which only the homochiral form was catalytically active.[10] Further studies demonstrated that the reaction was first-order in catalyst, close to second-order in aldehyde, but zero-order in the zinc alkyl reagent.

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(1R,2S)-N-Pyrrolidinylnorephedrine

Taylor

2003

Encyclopedia of Reagents for Organic Synthesis

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Enantioselective dialkylation of 1,2-phthalicdicarboxaldehyde

Cited by 9 publications

References 12 publications

Novel Approach to the Synthesis of Enantioenriched Sulfoxides. Highly Diastereoselective Alkylation of Sulfenate Anions with 1,4-Asymmetric Induction

Novel Approach to the Synthesis of Enantioenriched Sulfoxides. Highly Diastereoselective Alkylation of Sulfenate Anions with 1,4-Asymmetric Induction

Observation of a Transient Intermediate in Soai’s Asymmetric Autocatalysis: Insights from ¹H NMR Turnover in Real Time

(1R,2S)-N-Pyrrolidinylnorephedrine

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Enantioselective dialkylation of 1,2-phthalicdicarboxaldehyde

Cited by 9 publications

References 12 publications

Novel Approach to the Synthesis of Enantioenriched Sulfoxides. Highly Diastereoselective Alkylation of Sulfenate Anions with 1,4-Asymmetric Induction

Novel Approach to the Synthesis of Enantioenriched Sulfoxides. Highly Diastereoselective Alkylation of Sulfenate Anions with 1,4-Asymmetric Induction

Observation of a Transient Intermediate in Soai’s Asymmetric Autocatalysis: Insights from 1H NMR Turnover in Real Time

(1R,2S)-N-Pyrrolidinylnorephedrine

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Observation of a Transient Intermediate in Soai’s Asymmetric Autocatalysis: Insights from ¹H NMR Turnover in Real Time