Solvent-induced stereospecific isomerization of an allylic alcohol to a homoallylic alcohol catalyzed by a chiral lithium amide

Article Abstract:

Cyclohexene oxide is deprotonated by lithium (S)-2-(1-pyrrolidinylmethylpyrrolide) and yields the lithium alkoxide of the homoallylic alcohol, 3-cyclohexene-1-ol when the solvent is changed from tetrahydrofuran (THF) to 2,5-dimethyltetrahydrofuran (DMTHF) or diethyl ether (DEE). It also yields the lithium alkoxide of 2-cyclohexene-1-ol. The stereospecific isomerization of an allylic alcohol can be induced by solvent choice to for a homoallylic alcohol. The reaction is catalyzed by one of the chiral lithium amides.

Molecular electronics, Isomerization, Protons, Solvents, Stereoisomers

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Highly diastereoselective synthesis of 1,2-amino alcohols via nucleophilic addition of organocerium reagents to 4- and 5-oxazolidinonecarbaldehydes

Article Abstract:

Reacting chiral, nonracemic 5- and 4-oxazolidinonecarbaldehydes, 13 and 6, with organocerium reagents efficiently, with good-to-excellent diastereoselectivity, gives, respectively, anti and syn alcohols. A model for explanation of the observable diastereoselectivity of the reactions of 6 and 13 has been developed. The synthesis of C-18-D-ribo-phytosphingosine from the anti alcohol shows the usefulness for the described method of synthesis of amino alcohols.

Amino compounds, Organometallic compounds

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Diastereoselective alkoxymethylation of aromatic aldehydes with chiral lithiomethyl ethers: synthesis of optically active monoprotected glycols

Article Abstract:

Synthesis of optically active alpha-alkoxymethyl benzyl alcohols has been carried out using reaction of polysubstituted benzaldehydes with chiral alpha-alkoxymethyllithiums. The latter are easy to make using transmetallation of corresponding alpha-alkoxystannanes with n-butyllithium. Chemical yields of the transformation for the alpha-alkoxymethyl benzyl alcohols are good. Low asymmetric induction results.

Research, Reactivity (Chemistry), Aromatic compounds, Aldehydes, Enantiomers, Optical isomers, Glycols, Glycols (Class of compounds)

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