Nucleophilic α-Addition to Alkynoates. A Synthesis of Dehydroamino Acids

Trost, Barry M.; Dake, Gregory R.

doi:10.1021/ja971238z

Cited by 242 publications

(117 citation statements)

References 11 publications

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“…Trost and coworkers discovered that the addition of nitrogen pronucleophiles does indeed occur at the a-position of propiolate esters (Scheme 5.8). [56] Related experiments with methyl 2-heptynoate gave the expected products of a-addition, g-addition and isomerization to the corresponding diene. The ability to redirect the selectivity from the classical b-addition to an a-addition through the influence of phosphine catalysis is quite remarkable.…”

Section: Nucleophilic Addition To the A-and Gpositions Of Activated Amentioning

confidence: 98%

Nucleophilic Phosphine Organocatalysis

2004

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Phosphines have recently become popular choices as nucleophilic catalysts in organic synthesis. The unique reactivity of phosphines compared to amines has allowed the discovery of new nucleophilic addition reactions at the a-and g-positions of unsaturated carbonyl compounds, as well as novel [3 þ 2] and [4 þ 2] cycloaddition reactions of activated alkynes and alkenes. The accessibility of chiral phosphines has rendered several of these transformations enantioselective and has made possible the kinetic resolution of racemic secondary alcohols by phosphine-catalyzed acylation. This mini-review presents recent advances in nucleophilic phosphine organocatalysis for carbon-carbon bond formation.

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Section: Nucleophilic Addition To the A-and Gpositions Of Activated Amentioning

confidence: 98%

Nucleophilic Phosphine Organocatalysis

2004

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“…An unusual O-conjugate addition reaction of the phenol to methyl propiolate must have occurred in our case, [11][12][13] furnishing compounds 2 and 3. Usually, the O-conjugate addition is not very common for most enolate conjugate addition reactions.…”

Section: Resultsmentioning

confidence: 68%

“…A reasonable mechanism for this addition reaction 9,[11][12][13] is shown in Scheme 2. The first step of the process involves a Michael addition of triphenylphosphine to the propiolate, thus generating an active phosphonium intermediate (4).…”

Section: Resultsmentioning

confidence: 99%

Synthesis and stereochemical assignment of methyl 3-(3-hydroxyphenoxy) acrylate via cis-trans photoisomerization

Sairre¹,

Araújo²,

Silva³

et al. 2008

J. Braz. Chem. Soc.

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3-(3-Hidroxi-fenoxi)acrilato de metila (2), um novo e importante material de partida para inúmeras reações e um precursor potencial do produto natural 3-(3-hidroxi-fenoxi)-2-propenal (1), foi sintetizado a partir de resorcinol e propiolato de metila. A configuração trans da dupla ligação presente no composto 2 foi confirmada através de uma reação de fotoisomerização.Methyl 3-(3-hydroxyphenoxy)acrylate (2), a new and important starting material for several reactions and a potential precursor of the natural product 3-(3-hydroxyphenoxy)-2-propenal (1), was synthesized from resorcinol and methyl propiolate. The trans configuration of the double bond present in 2 was confirmed through a photoisomerization reaction.

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“…2). Until recently, however, there were only isolated examples of intermolecular reactions of this type [≤30% yield (9)(10)(11); instead, another phosphine-catalyzed process, isomerization to the dienone (Eq. 2) (12, 13), often intervened], and there were no reports of an enantioselective variant.…”

mentioning

confidence: 99%

Phosphine-catalyzed asymmetric additions of malonate esters to γ-substituted allenoates and allenamides

Sinisi

Sun

2010

Proc. Natl. Acad. Sci. U.S.A.

101

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Because carbonyl groups are ubiquitous in organic chemistry, the ability to synthesize functionalized carbonyl compounds, particularly enantioselectively, is an important objective. We have developed a straightforward and versatile method for catalytic asymmetric carbon-carbon bond formation at the γ-position of carbonyl compounds, specifically, phosphine-catalyzed additions of malonate esters to γ-substituted allenoates and allenamides. Mechanistic studies have provided insight into the reaction pathway.here are a variety of powerful methods for functionalizing carbonyl compounds in the α-and the β-positions, including classic approaches such as reacting enolates with electrophiles and adding nucleophiles to α,β-unsaturated carbonyl compounds (1, 2). In contrast, there are few general processes for incorporating new substituents in the γ-position of carbonyl compounds, particularly catalytic asymmetric reactions that form carboncarbon bonds (3).In pioneering early investigations, Trost and Lu demonstrated that phosphines can catalyze additions of certain carbon, nitrogen, and oxygen nucleophiles to the γ-position of 2-butynoates and 2,3-butadienoates (Eq. 1, EWG ¼ ester), as well as related compounds (4-8); for these electrophiles, the γ-carbon of the product is not a stereocenter. In contrast, for additions to homologues of these electrophiles, there is the potential to simultaneously form a new bond and to control the stereochemistry of the γ-carbon (Eq. 2). Until recently, however, there were only isolated examples of intermolecular reactions of this type [≤30% yield (9-11); instead, another phosphine-catalyzed process, isomerization to the dienone (Eq. 2) (12, 13), often intervened], and there were no reports of an enantioselective variant.

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Nucleophilic α-Addition to Alkynoates. A Synthesis of Dehydroamino Acids

Cited by 242 publications

References 11 publications

Nucleophilic Phosphine Organocatalysis

Nucleophilic Phosphine Organocatalysis

Synthesis and stereochemical assignment of methyl 3-(3-hydroxyphenoxy) acrylate via cis-trans photoisomerization

Phosphine-catalyzed asymmetric additions of malonate esters to γ-substituted allenoates and allenamides

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