Synthesis of γ-Hydroxy-α,β-unsaturated Esters and Nitriles from Chiral Cyanohydrins

Marcus, Jan; Meurs, Pauline J. van; Nieuwendijk, Adrianus M. C. H. van den; Porchet, Mathieu; Brussee, Johannes; Gen, A. Van Der

doi:10.1016/s0040-4020(00)00085-5

Cited by 11 publications

(2 citation statements)

References 12 publications

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“…[14] Thet hus synthesized enantioenriched epoxides were subjected to the reaction conditions,a nd the corresponding enantioenriched 2,4,5trisubstituted 1,3-oxazolidines were formed without erosion of the enantiomeric purity.W hereas in principle,f rom am echanistic point of view,t he reaction of enantioenriched alcohols 4 with imines 2 would also allow the synthesis of the same compounds,t his methodology has an advantage due to the high accessibility of enantioenriched epoxides 1 as substrates compared to the corresponding enantioenriched alcohols 4. [15] Finally,t he transformation of 1,3-oxazolidine 3aa was performed (Scheme 6). Ther eduction of the ester moiety of 3aa with LiAlH 4 followed by treatment with trifluoroacetic acid in amixed solvent of 1,4-dioxane and H 2 Oprovided the 2-aminobutane-1,4-diol derivative in good yield (Scheme 6a).…”

Section: Methodsmentioning

confidence: 99%

Ring Expansion of Epoxides under Brønsted Base Catalysis: Formal [3+2] Cycloaddition of β,γ‐Epoxy Esters with Imines Providing 2,4,5‐Trisubstituted 1,3‐Oxazolidines

2015

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A novel ring-expansion reaction of epoxides under Brønsted base catalysis was developed. The formal [3+2] cycloaddition reaction of β,γ-epoxy esters with imines proceeds in the presence of triazabicyclodecene (TBD) as a superior Brønsted base catalyst to afford 2,4,5-trisubstituted 1,3-oxazolidines in a highly diastereoselective manner. This reaction involves the ring opening of the epoxides with the aid of the Brønsted base catalyst to generate α,β-unsaturated esters having an alkoxide at the allylic position, which would formally serve as a synthetic equivalent of the 1,3-dipole, followed by a cycloaddition reaction with imines in a stepwise fashion. This methodology enables the facile synthesis of enantioenriched 1,3-oxazolidines from easily accessible enantioenriched epoxides.

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Section: Methodsmentioning

confidence: 99%

Ring Expansion of Epoxides under Brønsted Base Catalysis: Formal [3+2] Cycloaddition of β,γ‐Epoxy Esters with Imines Providing 2,4,5‐Trisubstituted 1,3‐Oxazolidines

2015

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“…Several diastereoselective synthetic sequences allow the preparation of chiral nitriles 1 , for example, the Wittig or Wittig-type reactions using chiral aldehydes or ketones, ,, the reaction between α-(arylsulfinyl)acetonitriles and aldehydes or ketones, ,,, the oxyselenylation−deselenylation reaction of alkenes, ,,− the addition of the cyanide anion to optically active epoxides, , the β-elimination reactions involving chiral dihydroxy nitriles, and the cyanation reaction of vinyl iodides by copper cyanide . Also, diastereoselective Wittig reactions were used for the preparation of aminonitriles 2 .…”

Section: Introductionmentioning

confidence: 99%

Diastereoselective and Enantiospecific Synthesis of γ-Substituted α,β-Unsaturated Nitriles from O-Protected Allylic Cyanohydrins

et al. 2006

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gamma-Functionalized alpha,beta-unsaturated nitriles are prepared diastereoselectively and enantiospecifically from enantioenriched cyanohydrin-O-phosphates and carbonates derived from alpha,beta-unsaturated aldehydes, either by palladium or iridium-catalyzed nucleophilic allylic substitution reactions with different nucleophiles. Appropriate reaction conditions for dibenzylamine, benzylamine, sodium azide, NaOAc, tetra-n-butylammonium acetate (TBAA), the corresponding sodium salts of phenol and N-hydroxysuccinimide and the carbonucleophile sodium dimethyl malonate are described. Different substituted O-protected cyanohydrins, such as carbonates and phosphates, derived from crotonaldehyde, (E)-hex-2-enal, oct-2-enal, 2-methylbut-2-enal, and cinnamaldehyde are used as allylic substrates. The substitution takes place with total retention of the configuration for the (E)-gamma-functionalized nitriles and with inversion of the configuration for the Z-isomers. In general, cyanohydrin-O-phosphates are the materials of choice to get the highest E-diastereoselectivity. Dibenzylamine is the best nucleophile for the synthesis of gamma-nitrogenated alpha,beta-unsaturated nitriles in the presence of either palladium or iridium catalysts when aliphatic compounds and cinnamaldehyde derivative are used (up to 98% dr). For the synthesis of gamma-oxygenated alpha,beta-unsaturated nitriles sodium or TBAA the reagents are selected to avoid epimerizations in up to 76% dr. Finally, the Tsuji-Trost reaction with sodium malonate works only under palladium catalysis in up to 70% dr.

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Ring Expansion of Epoxides under Brønsted Base Catalysis: Formal [3+2] Cycloaddition of β,γ‐Epoxy Esters with Imines Providing 2,4,5‐Trisubstituted 1,3‐Oxazolidines

2015

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A novel ring‐expansion reaction of epoxides under Brønsted base catalysis was developed. The formal [3+2] cycloaddition reaction of β,γ‐epoxy esters with imines proceeds in the presence of triazabicyclodecene (TBD) as a superior Brønsted base catalyst to afford 2,4,5‐trisubstituted 1,3‐oxazolidines in a highly diastereoselective manner. This reaction involves the ring opening of the epoxides with the aid of the Brønsted base catalyst to generate α,β‐unsaturated esters having an alkoxide at the allylic position, which would formally serve as a synthetic equivalent of the 1,3‐dipole, followed by a cycloaddition reaction with imines in a stepwise fashion. This methodology enables the facile synthesis of enantioenriched 1,3‐oxazolidines from easily accessible enantioenriched epoxides.

show abstract

Synthesis of γ-Hydroxy-α,β-unsaturated Esters and Nitriles from Chiral Cyanohydrins

Cited by 11 publications

References 12 publications

Ring Expansion of Epoxides under Brønsted Base Catalysis: Formal [3+2] Cycloaddition of β,γ‐Epoxy Esters with Imines Providing 2,4,5‐Trisubstituted 1,3‐Oxazolidines

Ring Expansion of Epoxides under Brønsted Base Catalysis: Formal [3+2] Cycloaddition of β,γ‐Epoxy Esters with Imines Providing 2,4,5‐Trisubstituted 1,3‐Oxazolidines

Diastereoselective and Enantiospecific Synthesis of γ-Substituted α,β-Unsaturated Nitriles from O-Protected Allylic Cyanohydrins

Ring Expansion of Epoxides under Brønsted Base Catalysis: Formal [3+2] Cycloaddition of β,γ‐Epoxy Esters with Imines Providing 2,4,5‐Trisubstituted 1,3‐Oxazolidines

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