Unusual carbon-carbon bond formations between allylboronates and acetals or ketals catalyzed by a peculiar indium(I) Lewis acid.
In(I)OTf has been uncovered as an effective Lewis acid catalyst for unprecedented nucleophilic substitution of acetals or ketals with allylboronates. A transmetalative S(N)1 mechanism is proposed in which a single In(I) center acts as a dual catalyst to activate both reagents sequentially. Contrary to the classic gamma-selectivity of allylsilanes (Hosomi-Sakurai reaction), this In(I)-catalyzed borono variant displays distinct alpha-selectivity. Substrate scope and functional group tolerance proved to be excellent.
Schneider
Uwe
U
Department of Chemistry, School of Science and Graduate School of Pharmaceutical Sciences, The University of Tokyo, The HFRE Division, ERATO, JST, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Dao
Hai T
HT
Kobayashi
Shū
S
D000080:Acetals / Q000737:chemistry*; D001897:Boronic Acids / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D007204:Indium / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure
D000080:Acetals; D001897:Boronic Acids; D007204:Indium; D002244:Carbon