PubMed · 12736645
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Catherine Zandonella. 2003-05-08. Dying cells dragged screaming under the microscope.. https://doi.org/10.1038/423106b
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We report the first examples of an intermolecular electrophilic O-amination of aliphatic alcohols. Thus, the new reagents, fluorenone oxime tosylate, 5a, or mesylate, 5b, permit O-amination of diverse alcohols in the presence of NaH under mild conditions. By following the formation of the resulting oxime ethers, 6, the reaction was shown to be sensitive to steric effects in the alcohol. Furthermore, the presence of an aromatic ring or of a double bond in the alcohol molecule (benzyl, allyl) was found to increase the reaction rate.
A strong asymmetric amplification is observed in the addition of diethylzinc on aromatic aldehydes in the presence of the bistriflamide of trans-1,2-diaminocyclohexane 3a. The asymmetric amplification originates from the insolubility of the catalyst precursor 3a of low enantiomeric excess (ee), with a concomitant large increase of ee for the minor soluble part of 3a. Controlled mono-N-acetylation of 3a (20% ee) at -78 degrees C allowed isolation of 4 possessing 90% ee. [reaction: see text].
Anionic four-electron donor-based palladacycle-catalyzed 1,4-additions of arylboronic acids with alpha,beta-unsaturated ketones and 1,2-additions of arylboronic acids with aldehydes and alpha-ketoesters are described. Our study demonstrated that palladacycles were highly efficient, practical catalysts for these addition reactions. The work described here not only opened a new paradigm for the application of palladacycles, but may also pave the road for other metalacycles as practically useful catalysts for such addition reactions including asymmetric ones. [reaction: see text].