99114-33-7Relevant academic research and scientific papers
Stereoselective synthesis of (E)-trisubstituted α,β-unsaturated amides and acids
Feuillet, Fred J. P.,Cheeseman, Matt,Mahon, Mary F.,Bull, Steven D.
, p. 2976 - 2989 (2007/10/03)
Potassium alkoxides of N-acyl-oxazolidin-2-one-syn-aldols undergo stereoselective elimination reactions to afford a range of trisubstituted (E)-αβ-unsaturated amides in >95% de, that may be subsequently converted into their corresponding (E)-αβ-unsaturated acids or (E)-αβ-unsaturated oxazolines in good yield. syn-Aldols derived from αβ-unsaturated aldehydes gave their corresponding trisubstituted (E)-αβ-unsaturated-amides with poorer levels of diastereocontrol, whilst there was a similar loss in (E)-selectivity during elimination of syn-aldols derived from chiral aldehydes. These elimination reactions proceed via rearrangement of the potassium alkoxide of the syn-aldol to a 1,3-oxazinane-2,4-dione enolate intermediate that subsequently eliminates carbon dioxide to afford a trisubstituted (E)-αβ-unsaturated amide. The (E)-selectivity observed during the ElcB-type elimination step has been rationalised using a simple conformational model that employs a chair-like transition state to explain the observed stereocontrol. The Royal Society of Chemistry 2005.
Stereoselective rearrangement of β-hydroxy-N-acyloxazolidin-2-ones to afford N-2-hydroxyethyl-1,3-oxazinane-2,4-diones
Feuillet, Fred J. P.,Niyadurupola, D. Gangani,Green, Rachel,Cheeseman, Matt,Bull, Steven D.
, p. 1090 - 1094 (2007/10/03)
Zinc alkoxides of syn- or anti-β-hydroxy-N-acyloxazolidin-2-ones undergo stereoselective rearrangement to afford their corresponding syn- or anti-N-2-hydroxyethyl-1,3-oxazinane-2,4-diones in good yield.
An (E)-selective synthesis of trisubstituted (E)-α, β-unsaturated acid derivatives
Feuillet, Fred J. P.,Robinson, Diane E. J. E.,Bull, Steven D.
, p. 2184 - 2185 (2007/10/03)
Potassium alkoxides of N-acyloxazolidin-2-one derived synaldolates undergo a novel tandem intramolecular cyclisation elimination reaction to afford trisubstituted (E)-α,β-unsaturated amides in high d.e., which may be converted into their corresponding acids or oxazolines in good yield.
An Activated Germanium Metal-Promoted, Highly Diastereoselective Reformatsky Reaction
Kagoshima, Hirotaka,Hashimoto, Yukihiko,Oguro, Dai,Saigo, Kazuhiko
, p. 691 - 697 (2007/10/03)
Activated germanium metal, prepared by the reduction of germanium(II) iodide with potassium metal, was found to promote the Reformatsky reaction effectively under mild conditions. In the presence of activated germanium metal, the reactions of α-bromo ketones 2a and 2b and α-bromo imides 2e and 2f with benzaldehyde (1a) proceeded smoothly to give the corresponding β-hydroxy carbonyl compounds 3a, 3b, 3e and 3f, respectively, in good yields and with good syn diastereo- selectivity. The activated germanium metal-promoted, asymmetric Reformatsky reaction of enantiomerically pure-oxazolidinone derivatives 2g-j with various aldehydes 1a-d was also examined; the highest diastereoselectivity was achieved when (1S,2R)-2-amino-1,2-diphenylethanol- derived 2j was used as the Reformatsky donor. The excellent diastereoselectivity could be explained in terms of the formation of a chairlike, six-membered transition state between the aldehyde and enolate as in the Zimmerman-Traxler model. A single recrystallization of the Reformatsky adducts, followed by hydrolysis and subsequent esterification, led to enantiomerically pure methyl 3-hydroxy- 2-methylalkanoates 10j-m, with almost quantitative recovery of the enantiomerically pure 2-oxazolidinone 14.
Triphenylphosphine/scandium(III) trifluoromethanesulfonate: A new agent for the reformatsky reaction of α-bromo carboxylic acid derivatives with aldehydes
Kagoshima, Hirotaka,Hashimoto, Yukihiko,Saigo, Kazuhiko
, p. 8465 - 8466 (2007/10/03)
The Ph3P/Sc(OTf)3 combination was found to be effective for the Reformatsky reaction; when α-bromo carboxylic acid derivatives were allowed to react with aldehydes in the presence of the Ph3P/Sc(OTf)3 combinatio
HIGHLY STEREOSELECTIVE REFORMATSKY REACTIONS OF 3-(2-BROMOPROPIONYL)-2-OXAZOLIDONE DERIVATIVES WITH VARIOUS ALDEHYDES
Ito, Yoshio,Terashima, Shiro
, p. 2821 - 2834 (2007/10/02)
The Reformatsky reactions of 3-(2-bromopropionyl)-2-oxazolidone derivatives with various aldehydes were investigated to elucidate the effects of substituents in the 2-oxazolidone moieties on their diastereoselectivities.The highest 2,3-syn-diastereoselect
Erythro-Directive Reduction of α-Substituted Alkanones by Means of Hydrosilanes in Acidic Media
Fujita, Makoto,Hiyama, Tamejiro
, p. 5415 - 5421 (2007/10/02)
Hydrosilane reduced α-oxy and α-amino ketones and β-keto acid derivatives in trifluoroacetic acid to afford the corresponding erythro alcohols with high diastereoselectivity.The reaction proceeded without racemization at the carbon α to the carbonyl group.The erythro-directive reduction was explained in terms of the proton-bridged Cram cyclic model and successfully applied to the synthesis of physiologically important amino alcohols such as l-ephedrine, l-methoxamine, and erythro-2-methyl-3-piperidino-1-phenylpropanol.
A HIGHLY STEREOSELECTIVE SYNTHESIS OF ALDOLS EMPLOYING THE REFORMATSKY REACTION OF 3-(2-BROMOPROPIONYL)-2-OXAZOLIDONE DERIVATIVES WITH VARIOUS ALDEHYDES
Ito, Yoshio,Terashima, Shiro
, p. 6629 - 6632 (2007/10/02)
The title reactions of sterically crowded 2-oxazolidone derivatives with achiral aldehydes in the presence of zinc dust were found to give various 2,3-syn-aldols as major products (at most, 2,3-syn:2,3-anti=98:2).While a 2,3-syn-3,4-syn-aldol could be sim
