Asymmetric Synthesis of Protected α-Amino Boronic Acid Derivatives with an Air- and Moisture-Stable Cu(II) Catalyst

Abstract

The asymmetric borylation of N-tert-butanesulfinyl imines with bis(pinacolato)diboron is achieved using a Cu(II) catalyst and provides access to synthetically useful and pharmaceutically relevant α-amino boronic acid derivatives. The Cu(II)-catalyzed reaction is performed on the benchtop in air at room temperature using commercially available, inexpensive reagents at low catalyst loadings. A variety of N-tert-butanesulfinyl imines, including ketimines, react readily to provide α-sulfinamido boronate esters in good yields and with high stereoselectivity. In addition, this transformation is applied to the straightforward, telescoped synthesis of α-sulfinamido trifluoroborates.

Towards Selective Mycobacterial ClpP1P2 Inhibitors with Reduced Activity against the Human Proteasome

“…7) (25). N -Sulfinimines 13a to -g were synthesized by condensation between tert -butylsulfinamide (compound 12) and aldehydes 11a to -g in the presence of copper sulfate and molecular sieves.…”

Stereoinvertive C–C Bond Formation at the Boron‐Bound Stereogenic Centers through Copper‐Bipyridine‐Catalyzed Intramolecular Coupling of α‐Aminobenzylboronic Esters

“…Such reactions are highly attractive because the starting enantioenriched organoborons are configurationally robust and easily accessible by asymmetric hydroboration and related transformation. [8][9][10][11] The reaction course of the cross-coupling process can be switched from stereochemically retentive to invertive, thereby allowing the reaction to afford either enantiomer even from single enantiomers of starting organoboron compounds. However, such boron-based stereospecific coupling processes have so far been limited to palladium-catalyzed reactions using organoboron compounds bearing a boron-bound trisubstituted stereogenic carbon center.…”

Asymmetric Synthesis of Secondary and Tertiary Boronic Esters

“…They,a nd others,w ere later able to develop an improved catalytic system by using more oxygen-and moisture-stable copper catalysts. [69,70] Li and co-workers used optically pure N-phosphinylimines in ar elated strategy for the synthesis bortezomib. [71] Using chiral ligands on copper, the groups of Lin [72] and Liao [73] have independently reported the asymmetric copper-catalysed borylation of Nbenzoyl and N-Boc aldimines in moderate to good levels of enantioselectivity.…”