Improved method for the conversion of pinacolboronic esters into trifluoroborate salts: facile synthesis of chiral secondary and tertiary trifluoroborates
作者:Viktor Bagutski、Abel Ros、Varinder K. Aggarwal
DOI:10.1016/j.tet.2009.10.002
日期:2009.11
A general method for the preparation of virtually any potassium trifluoroborate salt from the corresponding pinacolboronic ester is reported. Thus, conditions for an azeotropic removal of pinacol from the reaction mixture were found to afford the desired potassium trifluoroborates of sufficient purity (>95%) in nearly quantitative yields irrespective of the nature of the product. The utility of this
Use of alkyl 2,4,6-triisopropylbenzoates in the asymmetric homologation of challenging boronic esters
作者:Robin Larouche-Gauthier、Catherine J. Fletcher、Irantzu Couto、Varinder K. Aggarwal
DOI:10.1039/c1cc14469c
日期:——
(-)-Sparteine induced lithiation of primary 2,4,6-triisopropylbenzoates and subsequent homologation of boronicesters is reported. A comparative study with lithiated N,N-diisopropylcarbamates has demonstrated the superiority of the hindered benzoate.
Vinyl boron ate complexes of enantioenriched secondary alkyl pinacolboronic esters undergo stereospecific radical-induced 1,2-migration in radical polar crossover reactions. In this three-component process various commercially available alkyl iodides act as radical precursors and light is used for chain initiation. Subsequent oxidation and protodeborylation leads to valuable α-chiral ketones and chiral
Investigation of the Deprotonative Generation and Borylation of Diamine-Ligated α-Lithiated Carbamates and Benzoates by in Situ IR spectroscopy
作者:Rory C. Mykura、Simon Veth、Ana Varela、Lydia Dewis、Joshua J. Farndon、Eddie L. Myers、Varinder K. Aggarwal
DOI:10.1021/jacs.8b06871
日期:2018.11.7
Diamine-mediated α-deprotonation of O-alkyl carbamates or benzoates with alkyllithium reagents, trapping of the carbanion with organoboroncompounds, and 1,2-metalate rearrangement of the resulting boronate complex are the primary steps by which organoboroncompounds can be stereoselectively homologated. Although the final step can be easily monitored by 11B NMR spectroscopy, the first two steps, which