Copper(I)-catalyzed substitution of propargylic carbonates with diboron: selective synthesis of multisubstituted allenylboronates.
A versatile synthetic method for the preparation of the allenylboronates, Cu(I)-catalyzed reaction of propargylic carbonates with a diboron, is described. A Cu(O-t-Bu)-Xantphos catalyst system was effective for the preparation of various allenylboron compounds, allenylboronates with different substitution patterns, those with functional groups, and an axially chiral one. The Lewis acid promoted stereoselective addition to aldehydes leading to homopropargylic alcohols showed the usefulness of the new allenylboronates.
Ito
Hajime
H
Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan. hajito@sci.hokudai.ac.jp
Sasaki
Yusuke
Y
Sawamura
Masaya
M