Copper‐Mediated Dichotomic Borylation of Alkyne Carbonates: Stereoselective Access to (E)‐1,2‐Diborylated 1,3‐Dienes versus Traceless Monoborylation Affording α‐Hydroxyallenes

Abstract

A mild copper‐mediated protocol has been developed for borylation of alkynyl cyclic carbonates. Depending on the nature of the borylating reaction partner, either stereoselective diborylation of the propargylic surrogate takes place, providing convenient access to (E)‐1,2‐borylated 1,3‐dienes, or traceless monoborylation occurs, which leads to α‐hydroxyallenes as the principal product. The dichotomy in this borylation protocol has been scrutinized by several control experiments, illustrating that a relatively small change in the diboron(4) reagent allows for competitive alcohol‐assisted protodemetalation to forge an α‐hydroxyallene product under ambient conditions.

Advancement of vinylene carbonate as a coupling partner in metal-catalyzed C–H functionalization

“…In addition, other functionalized cyclic organic carbonates have also evolved into diversified appealing coupling partners in modern organic synthesis. [10][11][12][13] Generally, these five or six-membered saturated cyclic organic carbonates generate interesting zwitterionic intermediates upon decarboxylation under transition-metal (TM) catalysis, [14][15][16][17] and the remaining fragments further react with electrophiles or nucleophiles to delivery linear or cyclic products (Fig. 1).…”