An iron‐catalyzed asymmetric intramolecular cyclopropanation was realized in high yields and excellent enantioselectivity (up to 97 % ee) by using the iron complexes of chiral spiro‐bisoxazoline ligands as catalysts. The superiority of iron catalysts exhibited in this reaction demonstrated the potential abilities of this sustainable metal in asymmetric carbenoid transformation reactions.
well-established reaction for the amide synthesis from organic azides and carboxylic acids in the presence of phosphorous reagents. In contrary to this, it is notable that bis azide in the presence of triethylphosphite or trimethylphosphite does not afford the expected bis amides but affords the ethyl or methyl esters of the carboxylic acids respectively. This serendipitous observation when further investigated
An Examination of the Scope and Stereochemistry of the Ireland-Claisen Rearrangement of Boron Ketene Acetals
作者:Curtis A. Seizert、Eric M. Ferreira
DOI:10.1002/chem.201304384
日期:2014.4.7
The Ireland–Claisen rearrangement of boron ketene acetals is described. The boron ketene acetalintermediates are formed through a soft enolization that obviates the use of strong bases and the intermediacy of alkali metal enolates. Yields and diastereoselectivities of these rearrangements are very sensitive to the choice of boron reagent, even among those that have been shown to effect quantitative