Ir‐Catalyzed Enantioselective Synthesis of gem‐Diborylalkenes Enabled by 1,2‐Boron Shift

Abstract

Asymmetric cross‐couplings based on 1,2‐carbon migration from B‐ate complexes have been developed efficiently to access valuable organoboronates. However, enantioselective reactions triggered by 1,2‐boron shift have remained to be unaddressed synthetic challenge. Here, Ir‐catalyzed asymmetric allylic alkylation enabled by 1,2‐boron shift was developed. In this reaction, we disclosed that excellent enantioselectivities were achieved through an interesting dynamic kinetic resolution (DKR) process of allylic carbonates at the elevated temperature. Notably, the highly valuable (bis‐boryl)alkenes have enabled an array of diversifications to access versatile molecules. Extensive experimental and computational studies were conducted to elucidate the reaction mechanism of DKR process and clarify the origin of excellent enantioselectivities.

Regioselective 1,n-Diborylation of Alkylidenecyclopropanes Enabled by Catalysis with a Spirocyclic NHC IrIII Pincer Complex

“…Therefore, organic chemists have been seeking to develop more atom-economic strategies to prepare gem -bis­(boryl)­alkanes. In this respect, synthesis of gem -diborylalkanes from substrates of diazoalkanes, carbenes, carbonyl compounds, and boronate complexes involving 1,2-boron shift provided attractive alternatives. In addition, diborylation via C–H activation has also been studied by the groups of Hartwig, Chirik, Suginome, and others .…”