3d-Metal Catalyzed N- and C-Alkylation Reactions via Borrowing Hydrogen or Hydrogen Autotransfer

Abstract

The conservation of our element resources is a fundamental challenge of mankind. The development of alcohol refunctionalization reactions is a possible fossil carbon conservation strategy since alcohols can be obtained from indigestible and abundantly available biomass. The conservation of our rare noble metals, frequently used in key technologies such as catalysis, might be feasible by replacing them with highly abundant metals. The alkylation of amines by alcohols and related C–C coupling reactions are early examples of alcohol refunctionalization reactions. These reactions follow mostly the borrowing hydrogen or hydrogen autotransfer catalysis concept, and many 3d-metal catalysts have been disclosed in recent years. In this review, we summarize the progress made in developing Cu, Ni, Co, Fe, and Mn catalysts for C–N and C–C bond formation reactions with alcohols and amines using the borrowing hydrogen or hydrogen autotransfer concept. We expect that the findings in this field will inspire others to develop new efficient and selective earth-abundant metal catalysts for borrowing hydrogen or hydrogen autotransfer applications or to develop novel alcohol refunctionalization reactions that can be mediated by such metals.

Homogenous Meets Heterogenous and Electro‐Catalysis: Iron‐Nitrogen Molecular Complexes within Carbon Materials for Catalytic Applications

“…These carbonyls can be further used in tandem reactions, and condensed in situ with amines, indoles, or other alcohols . State‐of‐the‐art catalysts are homogeneous Rh, Ru and Ir complexes, although current efforts are focused towards base metals and heterogeneous catalysts (and ideally both) …”

“…[120] State-of-the-art catalysts are homogeneous Rh, Ru and Ir complexes, [121,122] although current efforts are focused towards base metals and heterogeneous catalysts (and ideally both). [123,124] Balaraman et al explored dehydrogenative processes using Fe/N@C, supported on exfoliated graphene oxide this time (Fe-phen@EGO-900, Scheme 5A). [125] Fe-phen@EGO-900 was first tested on N-heterocycle dehydrogenation, using 10 mol% tBuOK at 145°C under Ar, with the release of H 2 gas (33-94 % yield, 20 examples, Scheme 5B).…”

Ru(II)‐PBTNNXN complex bearing functional 2‐(pyridin‐2‐yl)benzo[d]thiazole ligand catalyzed α‐alkylation of nitriles with alcohols

“…Conventional synthesis of α ‐alkylated nitriles with hazardous alkyl halides and strong bases often suffers from generating environmentally unfriendly byproducts . Later, alkylation of nitriles via borrowing hydrogen strategy with alcohol as alkylation agent, has been developed as one of the most attractive and atom‐economic transformation, with only water as a byproduct …”

A Borrowing Hydrogen Strategy for Dehydrative Coupling of Aminoisoquinolines with Benzyl Alcohols in Water

“…[9] The borrowing hydrogen (or hydrogen autotransfer) methodology is recognized as an alternative atom-economic synthetic strategy for straightforward and efficient dehydrative coupling of amines with alcohols, since this method can be performed using stable, available, and low-toxic alcohols instead of halides or aldehydes. [10] However, heterocyclic amines nucleophiles pose a challenging in catalytic borrowing hydrogen reactions. In general, these nucleophiles are considered unsuitable to late-transition metal-catalyzed reactions due ments showed that benzylic C-H bond cleavage of benzyl alcohol was involved in the turnover limiting step (KIE = 4.4).…”