Nickel‐Catalyzed Regioselective Arylboration of Conjugated Dienes

Abstract

The nickel‐catalyzed arylboration of conjugated dienes is reported. Good 1,4‐regioselectivity and (E)‐stereoselectivity were obtained using isoprene, together with very good 1,2‐regioselectivity and (E)‐stereoselectivity using 1‐arylbutadienes. The high reactivity and selectivity of this process were dependent on the use of the appropriate nitrogen‐based ligand. Moreover, wide functional group tolerance was observed under mild reaction conditions. This protocol provides a path to allyl or homoallyl boronic ester derivatives starting from 1,3‐dienes, aryl bromides, and B2pin2. The downstream transformation of allyl boronic esters was also achieved, suggesting a strategy for the diastereoselective 1,2‐difunctionalization of isoprene and demonstrating the potential for the synthesis of complex molecules.

Ni-Catalyzed Reductive Allylation of α-Chloroboronates to Access Homoallylic Boronates

“…In recent years, transition-metal catalysis has become an important platform for the synthesis of homoallylic boronates (Scheme ). For instance, the transition-metal-catalyzed selective borylation of 1,3-dienes, including hydroborylation by Ito, Mazet, RajanBabu, and others as well as carboborylation by Brown and others, was an ingenious strategy to construct homoallylic boronates (Scheme a); however, the above-mentioned borylation methods can prepare only primary homoallylic boronates, and they are not suitable for the synthesis of the secondary homoallylic boronates. Of note, homoallylic boronates could also be procured by the allylation of vinyl boronates (Scheme b) .…”

Recent progress in nickel-catalyzed carboboration of alkenes

“…Symmetric trisubstituted alkenes also perform well in the reaction and generate a single regioisomer in every case (27). This process was also extended to reaction of a cycloalkene (28) to generate the target product. A wide range of aryl bromides were also evaluated with alkenes.…”

“…Subsequently, Yin and co-workers 28 reported the Ni-catalyzed arylboration of conjugated dienes to get desired products in 2021. It was found that the reactivity and selectivity of this synthetic procedure were governed by the nitrogen-based ligand.…”

Recent Advances in Nonprecious Metal Catalysis

“…Using PyrOx ligands, Yin and co-workers demonstrated that the arylboration of isoprene and derivatives could undergo selective 1,4-addition with good E-selectivity (Scheme 15). 35 However, under the same conditions, aryl-substituted dienes produced the 1,2-addition products in poor yield. Ligand optimization for these aryl substrates showed that pyridylamides produced the 1,2-addition products in high yield and selectivity.…”