Regio- and Stereospecific Copper-Catalyzed Substitution Reaction of Propargylic Ammonium Salts with Aryl Grignard Reagents

We have developed a copper-catalyzed substitution reaction of propargylic ammonium salts with aryl Grignard reagents. The reaction is stereospecific and α-regioselective and proceeds with exceptional functional group tolerance. Conveniently, a stable, inexpensive, and commercially available copper salt is used and no added ligand is required

Copper(I)-Catalyzed Formal Carboboration of Alkynes: Synthesis of Tri- and Tetrasubstituted Vinylboronates

The first copper-catalyzed formal carboboration of alkynes, in which a C–B bond and a C–C bond are created in a single catalytic cycle, is presented. The reaction proceeds with high regioselectivity and <i>syn</i>-stereoselectivity to form tri- and tetrasubstituted vinylboronic esters from commercially available bis­(pinacolato)­diboron. A subsequent cross-coupling reaction gives access to highly substituted alkenes

Copper-Catalyzed Diastereo- and Enantioselective Desymmetrization of Cyclopropenes: Synthesis of Cyclopropylboronates

A novel Cu-catalyzed diastereo- and enantioselective desymmetrization of cyclopropenes to afford nonracemic cyclo­propyl­boronates is described. Trapping the cyclo­propyl­copper intermediate with electrophilic amines allows for the synthesis of cyclo­propyl­amino­boronic esters and demonstrates the potential of the approach for the synthesis of functionalized cyclopropanes

Copper-Catalyzed Borylative Aromatization of <i>p</i>‑Quinone Methides: Enantioselective Synthesis of Dibenzylic Boronates

In this report, we establish that DM-Segphos copper­(I) complexes are efficient catalysts for the enantioselective borylation of <i>para</i>-quinone methides. This method provides straightforward access to chiral monobenzylic and dibenzylic boronic esters, with enantiomeric ratios up to 96:4, using a commercially available chiral phosphine. Standard manipulations of the C–B bond afford a variety of chiral diaryl derivatives