Synthesis of 1,3‐Bis‐(boryl)alkanes through Boronic Ester Induced Consecutive Double 1,2‐Migration

Abstract

A general and efficient approach for the preparation of 1,3‐bis‐(boryl)alkanes is introduced. It is shown that readily generated vinylboron ate complexes react with commercially available ICH2Bpin to valuable 1,3‐bis‐(boryl)alkanes. The introduced transformation, which is experimentally easy to conduct, shows broad substrate scope and high functional‐group tolerance. Mechanistic studies reveal that the reaction does not proceed via radical intermediates. Instead, an unprecedented boronic ester induced sequential bis‐1,2‐migration cascade is suggested.

Cyclic (Alkyl)(amino)carbene Ligands Enable Cu‐Catalyzed Markovnikov Protoboration and Protosilylation of Terminal Alkynes: A Versatile Portal to Functionalized Alkenes**

“…The extracts were dried over anhydrous Na2SO4 and concentrated in vacuo. The crude product was purified S27 using silica gel column chromatography (Hexane/Et2O = 100/1) gave the product 3ac as colorless liquid ( Procedure K: Following Studer's procedure 25 , 2a (54.4 mg, 0.200 mmol) was dissolved in diethyl ether (2.0 mL) and n-BuLi (2.5 M) in hexane solution (88.0 μL, 0.220 mmol) was added dropwise over 5 minutes at 0 °C. The solution was then stirred for 0.5 h at 0 °C, warmed to room temperature and stirred for a further 0.5 h. Subsequently, the solvent was carefully removed in vacuo and the resulting residue was taken up in acetonitrile (2.0 mL).…”

Cyclic(Alkyl)(Amino)Carbene Ligands Enable Cu-Catalyzed Markovnikov Protoboration and Protosilylation of Terminal Alkynes: A Versatile Portal to Functionalized Alkenes

“…We were able to synthesize a 1,3-bis-(boryl)alkane 3ad via a boronic ester induced bis-1,2-migration pathway, following Studer's procedure. 16 In addition, Fe-catalyzed HAT olefin cross-coupling reaction between 2a and N,N-dimethylacrylamide gave 3ae in useful yield, under Baran's conditions with slight modifications. 17 Finally, with mCPBA as an oxidant, epoxidation of 2af giving 3af was achieved in 89% yield.…”

Cyclic (Alkyl)(amino)carbene Ligands Enable Cu‐Catalyzed Markovnikov Protoboration and Protosilylation of Terminal Alkynes: A Versatile Portal to Functionalized Alkenes**

“…The extracts were dried over anhydrous Na2SO4 and concentrated in vacuo. The crude product was purified S27 using silica gel column chromatography (Hexane/Et2O = 100/1) gave the product 3ac as colorless liquid ( Procedure K: Following Studer's procedure 25 , 2a (54.4 mg, 0.200 mmol) was dissolved in diethyl ether (2.0 mL) and n-BuLi (2.5 M) in hexane solution (88.0 μL, 0.220 mmol) was added dropwise over 5 minutes at 0 °C. The solution was then stirred for 0.5 h at 0 °C, warmed to room temperature and stirred for a further 0.5 h. Subsequently, the solvent was carefully removed in vacuo and the resulting residue was taken up in acetonitrile (2.0 mL).…”