Increased Felkin–Anh selectivity in nucleophilic additions to α-chiral aldehydes using vinylalanes

Spino, Claude; Granger, Marie-Claude; Boisvert, Luc; Beaulieu, Christian

doi:10.1016/s0040-4039(02)00753-0

Cited by 11 publications

(6 citation statements)

References 9 publications

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“…We made a series of allylic alcohols 12 using this method (Table , method A). Reports of the addition of vinylalanes to aldehydes are scant and we were first to report their stereoselective addition to chiral aldehydes . The reason for this enhanced stereoselectivity eluded us for some time until we realized that the excess trimethylaluminum used to generate the vinylalane, as per the Negishi protocol, was in fact responsible for the high stereoselectivity .…”

Section: Introductionmentioning

confidence: 99%

p-Menthane-3-carboxaldehyde: A Useful Chiral Auxiliary for the Synthesis of Chiral Quaternary Carbons of High Enantiomeric Purity

et al. 2004

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(+)- or (-)-p-Menthane-3-carboxaldehyde is made in two easy steps from (+)- or (-)-menthone, respectively. This auxiliary allows for the synthesis of carbonyl compounds bearing a alpha-chiral quaternary carbon. The flexibility, efficiency, and ease of use of the method are demonstrated in a series of examples, which include the total synthesis of (+)-cuparenone as well as a partial synthesis of (-)-cassiol.

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Section: Introductionmentioning

confidence: 99%

p-Menthane-3-carboxaldehyde: A Useful Chiral Auxiliary for the Synthesis of Chiral Quaternary Carbons of High Enantiomeric Purity

et al. 2004

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“…For a while, we believed that the purported vinylalane intermediate 44a, obtained from the carboalumination reaction of 45a, was responsible for this dramatic increase in stereoselectivity. 30 However, serendipitous removal of excess trimethylaluminium by evaporation soon revealed that it was responsible for the high stereoselectivity observed. Could excess AlMe 3 also increase the stereoselectivity of other vinylmetals?…”

Section: Alkylations To Make 41 Chiral Carbonsmentioning

confidence: 99%

Menthone and p-menthyl-3-carboxaldehyde as chiral auxiliaries

Spino

2011

Chem. Commun.

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“…[28][29][30][31][32] Metalation of (Z)-vinyliodides with n-BuLi or i-PrMgBr followed by addition to chiral aldehydes is also attractive but usually proceeds with reduced diastereoselectivity due to the reactive nature of these organometallic reagents (Scheme 1C). 33,34 Alternatively, softer nucleophiles based on Zn and Al, various additives, and Lewis acids are often employed to increase the selectivity. [33][34][35][36] These methods are dependent on the availability of (Z)-vinyl iodides with high stereochemical purity.…”

Section: Introductionmentioning

confidence: 99%

“…33,34 Alternatively, softer nucleophiles based on Zn and Al, various additives, and Lewis acids are often employed to increase the selectivity. [33][34][35][36] These methods are dependent on the availability of (Z)-vinyl iodides with high stereochemical purity.…”

Section: Introductionmentioning

confidence: 99%

One-Pot Multicomponent Coupling Methods for the Synthesis of Diastereo- and Enantioenriched (Z)-Trisubstituted Allylic Alcohols

et al. 2009

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Abstract(Z)-Trisubstituted allylic alcohols are widespread structural motifs in natural products and biologically active compounds but are difficult to directly prepare. Introduced herein is a general one-pot multicomponent coupling method for the synthesis of (Z)-α,α,β-trisubstituted allylic alcohols. (Z)-Trisubstituted vinylzinc reagents are formed in situ by initial hydroboration of 1-bromo-1-alkynes. Addition of dialkylzinc reagents induces a 1,2-metallate rearrangement that is followed by a boron-to-zinc transmetallation. The resulting vinylzinc reagents add to a variety of prochiral aldehydes to produce racemic (Z)-trisubstituted allylic alcohols. When enantioenriched aldehyde substrates are employed (Z)-trisubstituted allylic alcohols are isolated with high dr (>20:1 in many cases). For example, vinylation of enantioenriched benzyl protected α-and β-hydroxy propanal derivatives furnished the expected anti-Felkin addition products via chelation control. Surprisingly, silyl protected α-hydroxy aldehydes also afford anti-Felkin addition products. A protocol for the catalytic asymmetric addition of (Z)-trisubstituted vinylzinc reagents to prochiral aldehydes with a (−)-MIB-based catalyst has also been developed. Several additives were investigated as inhibitors of the Lewis acidic alkylzinc halide byproducts, which promote the background reaction to form the racemate. α-Ethyl and α-cyclohexyl (Z)-trisubstituted allylic alcohols can now be synthesized with excellent levels of enantioselectivity in the presence of diamine inhibitors.

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Increased Felkin–Anh selectivity in nucleophilic additions to α-chiral aldehydes using vinylalanes

Cited by 11 publications

References 9 publications

p-Menthane-3-carboxaldehyde: A Useful Chiral Auxiliary for the Synthesis of Chiral Quaternary Carbons of High Enantiomeric Purity

p-Menthane-3-carboxaldehyde: A Useful Chiral Auxiliary for the Synthesis of Chiral Quaternary Carbons of High Enantiomeric Purity

Menthone and p-menthyl-3-carboxaldehyde as chiral auxiliaries

One-Pot Multicomponent Coupling Methods for the Synthesis of Diastereo- and Enantioenriched (Z)-Trisubstituted Allylic Alcohols

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