Details

Autor(en) / Beteiligte

• Shimoi, Masaki
• Watanabe, Takashi
• Maeda, Katsuhiro
• Curran, Dennis P.
• Taniguchi, Tsuyoshi

Titel

Radical trans‐Hydroboration of Alkynes with N‐Heterocyclic Carbene Boranes

Ist Teil von

• Angewandte Chemie (International ed.), 2018-07, Vol.57 (30), p.9485-9490

Auflage

International ed. in English

Ort / Verlag

Germany: Wiley Subscription Services, Inc

Erscheinungsjahr

2018

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Hydroboration of internal alkynes with N‐heterocyclic carbene boranes (NHC‐boranes) occurs to provide stable NHC (E)‐alkenylboranes upon thermolysis in the presence of di‐tert‐butyl peroxide. The E isomer results from an unusual trans‐hydroboration, and the E/Z selectivity is typically high (90:10 or greater). Evidence suggests that this hydroboration occurs by a radical‐chain reaction involving addition of an NHC‐boryl radical to an alkyne to give a β‐NHC‐borylalkenyl radical. Ensuing hydrogen ion from the starting NHC‐borane provides the product and returns the starting NHC‐boryl radical. Experiments suggest that the observed trans‐selectivity results from kinetic control in the hydrogen‐transfer reaction. Entgegen it is: Radical hydroboration of alkynes with N‐heterocyclic carbene boranes (NHC‐boranes) has been developed. The reaction occurs in a highly trans‐selective manner to provide bench‐stable NHC (E)‐alkenylboranes from internal alkynes.