Abstract
A highly selective copper‐catalyzed trifunctionalization of allenes has been established based on diborylation/cyanation with bis(pinacolato)diboron (B2pin2) and N‐cyano‐N‐phenyl‐p‐toluenesulfonamide (NCTS). The Cu‐catalyzed trifunctionalization of terminal allenes is composed of three catalytic reactions (first borocupration, electrophilic cyanation, and second borocupration) that provide a densely functionalized product with regio‐, chemo‐ and diastereoselectivity. Allene substrates have multiple reaction‐sites, and the selectivities are determined by the suitable interactions (e.g., electronic and steric demands) between the catalyst and substrates. We employed DFT calculations to understand the cascade copper‐catalyzed trifunctionalization of terminal allenes, providing densely‐functionalized organic molecules with outstanding regio‐, chemo‐ and diastereoselectivity in high yields. The selectivity challenges presented by cumulated π‐systems are addressed by systematic computational studies; these give insight to the catalytic multiple‐functionalization strategies and explain the high selectivities that we see for these reactions.
Cu‐catalyzed trifunctionalization of terminal allenes, through three catalytic reactions (borocupration, electrophilic cyanation, followed by a second borocupration), provides a densely functionalized product with regio‐, chemo‐ and diastereoselectivity (see figure). Density functional theory calculations help to understand the cascade catalytic mechanism.