Metal-free σ-bond metathesis in 1,3,2-diazaphospholene-catalyzed hydroboration of carbonyl compounds.
The first metal-free catalytic hydroboration of carbonyl derivatives has been developed in which a catalytic amount of 1,3,2-diazaphospholene effectively promotes a hydroboration reaction of aliphatic and aromatic aldehydes and ketones. The reaction mechanism involves the cleavage of both the PO bond of the alkoxyphosphine intermediate and the BH bond of pinacolborane as well as the formation of PH and BO bonds. Thus, the reaction proceeds through a non-metal σ-bond metathesis. Kinetic and computational studies suggest that the σ-bond metathesis occurred in a stepwise but nearly concerted manner.
Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Nanyang Link 21, Singapore 637371 (Singapore).
Che Chang
CC
Chong
Hajime
H
Hirao
Rei
R
Kinjo
hydroboration; main-group catalysts; metal-free catalysis; phosphanes; σ-bond metathesis