Stepwise Oxygenation of Pinacolborane by a Rhodiumperoxo Complex: Detection of an Intermediate Metal Borate and Perborate

Abstract

Acting as go‐between: A rhodium borate and perborate have been identified as intermediates in the rhodium‐mediated oxygenation of pinacolborane (HBpin; see scheme). The rhodium(III)–peroxo complex reacts with the Lewis acidic boron compound HBpin by oxygen transfer from the rhodium center to HBpin to give a rhodium(I) species. The reaction sequence might play a crucial role in the homocoupling of boronic acid.

Mechanistic Investigation of the Palladium-Catalyzed Synthesis of Allylic Silanes and Boronates from Allylic Alcohols

“…The product ( 6a ) and the excess B 2 pin 2 (pin = pinacolato) gave rise to two partially overlapping peaks at 32 and 30 ppm (Figure ). The only byproduct observed containing a Bpin adduct is pinB–OH ( 16 ) . Analogously to the silylation reaction, B­(OR) 3 (R = H or CD 3 ) is also formed, but in larger amounts; B­(OR) 3 is formed mainly via hydrolysis of pinB–OH and not only from the catalyst counterion BF 4 – .…”

Consecutive C–F bond activation and C–F bond formation of heteroaromatics at rhodium: the peculiar role of FSi(OEt)3

“…Note that the signal for the fluorine atom at the ortho position to the nitrogen atom in 13 characteristically appears at low field in the 19 F NMR spectrum. 5a , h , 6 , 20 However, conversions of 13 and 14 in the presence of FSi(OEt) 3 led to the formation of the products of fluorination [Rh{4-(2,3,5-C 5 F 3 HN)}(PEt 3 ) 3 ] ( 7 ) and [Rh{4-(2,3,6-C 5 F 3 HN)}(PEt 3 ) 3 ] ( 12 ) ( Scheme 4 ). These conversions took place at a slower rate when compared to the reaction of 2 with FSi(OEt) 3 .…”

Oxygenation of a Ruthenium Complex Bearing a PBP-Pincer Ligand Inducing the Formation of a Boronato Ligand with a Weak Ru–O Bond

“…Detailed structural parameters afforded a further understanding of the properties of 4 in comparison with the reference compound 5 (Table ). Complex 5 has the same d 6 configuration, the atomic size of Rh (1.25 Å) is similar to that of Ru (1.24 Å), and it has a boronate ligand, a hydride ligand cis to boronate, and a π-accepting ligand trans to boronate.…”