CeO₂‐Nanorods‐Catalyzed Protoboration of Alkenes and Alkynes with Bis(pinacolato)diboron

Abstract

The protoboration of alkenes and alkynes with B 2 pin 2 (pin = OCMe 2 CMe 2 O) using a heterogeneous CeO 2 nanorods catalyst has been developed to afford the corresponding alkyl and vinyl boronate esters in 41-99% yield under mild reaction conditions. A series of aromatic and aliphatic alkenes and alkynes with synthetically important functional groups were well tolerated. In both the systems, the catalyst could be reused for up to six runs without significant loss in activity. Stoichiometric reactions revealed that the protoboration may proceed through the in situ formed catalytically active boryl species.

Transition metal- and solvent-free anti-Markovnikov selective protoboration of alkenes with bis(pinacolato)diboron

“…5 The transition-metal-catalyzed hydroboration of alkenes with borane derivatives (HBR 1 R 2 ) and diboron reagents has emerged as one of the most powerful synthetic protocols for obtaining such derivatives. 6 To date, several precious 7 and non-precious metals, 8 main group elements, 9 and lanthanide-based catalysts 10 have been developed for the hydroboration of alkenes. Furthermore, a handful of examples of heterogeneous catalytic systems for the hydroboration of unsaturated hydrocarbons have also been reported.…”

Alumina-Promoted Copper-Catalyzed Hydroboration of Alkynes

“…The development of Cu(I)-catalyzed addition of copper-boryl species to alkynes made a landmark in the preparation of vinylboronates. 17 The use of air-stable bis(pinacolato)diboron (B 2 Pin 2 ) 18 allowed to significantly simplify the experimental procedure and even perform the hydroboration in air and aqueous media. 19 Another striking point of this approach is the regioselectivity, which is opposite to Cu-catalyzed hydroboration with HBPin (Scheme 1A).…”