Stereoselective Thio-Michael/Aldol Tandem Reaction to α,β-Unsaturated Esters

Kamimura, Akio; Mitsudera, Hiromasa; Asano, Shigeru; Kidera, Seiji; Kakehi, Akikazu

doi:10.1021/jo990548s

Cited by 59 publications

(25 citation statements)

References 24 publications

(21 reference statements)

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“…The conformation of the enolate isˆxed by an allylic strain, and the approach of aldehyde takes place anti to C S bond with a coordination of aldehyde oxygen to lithium as shown in A. Coincidently to us, Kamimura's group reported similar stereoselectivity in thiolate-initiated Michael aldol tandem reaction of acrylates with aldehydes. [73][74] MICHAEL ALDOL TANDEM CYCLIZATION REACTION 75) Stereoselective Michael aldol tandem cyclization reaction was developed by an extension of the intermolecular reaction to an intramolecular reaction of v-oxo-a,b-enoate which has enoate and aldehyde moieties in a molecule. Tandem cyclization reactions, especially Michael Michael reactions, have been reported with the re‰ection of an importance of ring skeleton construction.…”

Section: Tandem Michael Aldol Carbon Carbon Bond-forming Reactionmentioning

confidence: 99%

Asymmetric Conjugate Addition of Arylthiols to Enoates and Its Application to Organic Synthesis of Biologically Potent Compounds

Nishimura

Tomioka

2003

YAKUGAKU ZASSHI

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As a part of our studies aimed at asymmetric catalytic reactions by using an external chiral ligand, we have developed a catalytic asymmetric addition reaction of an arylthiol to a,b-unsaturated esters under the control of an external chiral ligand. The characteristic of our technology is a double activation of a thiol by lithiation and chelate formation with a chiral tridentate amino diether ligand, which simultaneously and eŠectively controls a stereochemistry of the reaction. One signiˆcant feature of an arylthiol is a bulky 2-substitution on aryl group, which enables the formation of a really reactive monomeric thiolate species. s-Cis conformation and capability of electron lone pair-diŠerentiating coordination of a carbonyl oxygen to lithium are structural requirements of the substrates for high enantioselectivity. The enantioselectivity came up to 97％ under the cited conditions. Asymmetric protonation of a transient enolate, generated by conjugate addition of a lithium thiolate to an enoate, was also realized. The stereochemistry of the protonation was controlled by the conformation of initially formed transient enolate in a 1,2-asymmetric induction manner. This technology enabled the asymmetric synthesis of (S)-naproxene. Stereoselective tandem C S and C C bond-forming reaction was developed as a logical extension by trapping the transient enolate intermediate with an aldehyde as a carbo-electrophile in the presence of phenylthiotrimethylsilane as an equilibrium-shift reagent. This tandem reaction was extended to a stereoselective cyclization of v-oxo-a,b-unsaturated esters initiated by a lithium thiolate. Stereoselectivity of both tandem inter-and intramolecular reaction is predictable by an allylic strain-controlled conformation model of the enolate, in which an approach of aldehyde takes place anti to C S bond through coordination of an aldehyde oxygen to lithium. Total synthesis of (-)-neplanocin A was achieved by using the tandem cyclization as a key tool for the direct construction of aˆve-membered carbocycle where every carbon is functionalized.

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Section: Tandem Michael Aldol Carbon Carbon Bond-forming Reactionmentioning

confidence: 99%

Asymmetric Conjugate Addition of Arylthiols to Enoates and Its Application to Organic Synthesis of Biologically Potent Compounds

Nishimura

Tomioka

2003

YAKUGAKU ZASSHI

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“…When the transition β-thio-enolate cannot be protonated due to the aprotic environment, it is possible to use it in the aldol reaction. This approach was proposed by Kamimura in 1998 and presented as a new kind of tandem Michael/aldol reaction (scheme 1) [4]. Scheme 1.…”

Section: Introductionmentioning

confidence: 99%

Intramolecular Tandem Seleno-Michael/Aldol Reaction—Novel Strategy in Carbasugars Synthesis

Banachowicz

Biduś

Buda

2020

The 1st International Electronic Conference on Catalysis Sciences

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Carbasugars are a wide group of carbohydrate mimetics in which the ring oxygen had been replaced by a methylene group. The high importance of these compounds is related to their interesting biological and pharmacological properties which are the matter of current studies. In our work, concise synthesis of carbasugars from naturally occurring D-pentoses is presented. The onepot seleno-Michael reaction connected with intramolecular aldol reaction is a key step of the carbasugar core asymmetric synthesis. Further transformation of obtained carbasugar moiety led to different bioactive compounds. Tandem seleno-Michael reaction conjugated with oxidation/elimination step of in situ generated nucleophile has been described a few years ago in the intermolecular variant. In our work, we present the first example of this reaction in an intramolecular way which leads to a previously inaccessible cyclic product of Morita-Baylis-Hillman reaction. Conducted experiments allowed to receive cyclic products with high yields and good diastereoisomeric excesses.

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“…Acetylenic sulfones are known as electrophiles, 14 whereas selenolate and its analogues are good nucleophiles for Michael addition. 15 The tandem reaction has recently been of interest for organic synthesis because it offers a convenient and economical method to prepare desired organic molecules. [16][17][18][19] Huang and Xie reported the stereo-selective Michael-aldol tandem reaction of phenylselenomagnesium bromide with acetylenic sulfones and carbonyl compounds, providing a simple and efficient one-pot protocol for the synthesis of difunctionalised tetrasubstituted alkenes.…”

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confidence: 99%

Regio- and Stereoselective Synthesis of Tetrasubstituted Olefins by the Three-Component Tandem Reaction of Phenylselenomagnesium Bromide, Acetylenic Sulfones and Allylic Bromides

Huang

You

Cai

2010

Journal of Chemical Research

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Stereoselective Thio-Michael/Aldol Tandem Reaction to α,β-Unsaturated Esters

Cited by 59 publications

References 24 publications

Asymmetric Conjugate Addition of Arylthiols to Enoates and Its Application to Organic Synthesis of Biologically Potent Compounds

Asymmetric Conjugate Addition of Arylthiols to Enoates and Its Application to Organic Synthesis of Biologically Potent Compounds

Intramolecular Tandem Seleno-Michael/Aldol Reaction—Novel Strategy in Carbasugars Synthesis

Regio- and Stereoselective Synthesis of Tetrasubstituted Olefins by the Three-Component Tandem Reaction of Phenylselenomagnesium Bromide, Acetylenic Sulfones and Allylic Bromides

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