Tetrahydroxydiboron-Mediated Palladium-Catalyzed Transfer Hydrogenation and Deuteriation of Alkenes and Alkynes Using Water as the Stoichiometric H or D Atom Donor

Abstract

There are few examples of catalytic transfer hydrogenations of simple alkenes and alkynes that use water as a stoichiometric H or D atom donor. We have found that diboron reagents efficiently mediate the transfer of H or D atoms from water directly onto unsaturated C-C bonds using a palladium catalyst. This reaction is conducted on a broad variety of alkenes and alkynes at ambient temperature, and boric acid is the sole byproduct. Mechanistic experiments suggest that this reaction is made possible by a hydrogen atom transfer from water that generates a Pd-hydride intermediate. Importantly, complete deuterium incorporation from stoichiometric D2O has also been achieved.

Highly Crystalline K‐Intercalated Polymeric Carbon Nitride for Visible‐Light Photocatalytic Alkenes and Alkynes Deuterations

“…[5] Thus, developing a general approach combining new catalytic system with green and inexpensive deuterium source (D-source) for selective deuteration of alkenes and alkynes with broad reaction scope is highly desired. [5] Thus, developing a general approach combining new catalytic system with green and inexpensive deuterium source (D-source) for selective deuteration of alkenes and alkynes with broad reaction scope is highly desired.…”

Metal‐Free Hydrogen Atom Transfer from Water: Expeditious Hydrogenation of N‐Heterocycles Mediated by Diboronic Acid

“…Very recently, the Stokes group developed a palladium‐catalyzed transfer hydrogenation of alkenes and alkynes with stoichiometric water mediated by diboronic acid. Mechanistic results suggested the reaction proceeds with hydrogen transfer from water onto palladium species to generate Pd‐hydride intermediates (Scheme b) . Notably, transition metals are crucial to activate or enable the hydrogen transfer in current studies.…”

Iron‐ or Palladium‐Catalyzed Reaction Cascades Merging Cycloisomerization and Cross‐Coupling Chemistry

“…Moreover, product 48 shows that boryl transfer is possible: interestingly though, the use of tetrahydroxydiboron resulted in selective reduction of the triple bond of the substrate to give 47 , without any borylative cyclization being detectable. This somewhat counterintuitive outcome has precedent in the literature . In contrast, activation of B 2 (pin) 2 with MeLi generated a suitable boryl‐transfer agent, although the purification of the resulting product proved difficult, most likely because the released phenolate is non‐innocent vis‐à‐vis the boron moiety.…”