Electrochemical Studies on the Nickel-Catalyzed O−C(allyl) Bond Cleavage of Allyl Ethers

Abstract

The chemoselective electrochemical cleavage of allyl aryl ethers catalyzed by Ni(bipy) 3 2+ 2BF 4 -was shown to proceed through electrogenerated Ni(0) complexes with the formation of π-allyl Ni(II) species, which are in turn reduced at the same potential as the initial Ni(II)/Ni(0) reduction. The important role of magnesium ions in the recycling of the nickel species was established.

Electrochemical Reduction of a Racemic Allyl β-Keto Ester Catalyzed by Nickel Complexes: Asymmetric Induction

“…[13] The formation of π-allyl Ni II complexes from Ni 0 and allyl derivatives has been reported in chemical, [14] as well as in electrochemical reactions. [15,16] The formation of 2 and 3 can be explained by deallylation with or without decarboxylation, and 4 is formed from an intramolecular allyl transfer reaction to the carbonyl group, as in recently described reactions. [16] In the overall process, the anode (Mg or Zn) provides Mg 2ϩ or Zn 2ϩ ions in solution.…”

Asymmetric Electrochemical Transformations

“…Control experiments showed that no reaction occurred in the absence of current or complex 74 . The reaction initially proceeds through the electrochemical generation of a Ni 0 complex, which oxidatively adds to the C−O bond of the allyl ester group to form a π‐allyl Ni II complex . The corresponding chiral ketone products 73 can be generated through the sequential deallylation/decarboxylations/asymmetric protonation process to provide a modest level of asymmetric induction.…”

Intramolecular reductive cyclisations using electrochemistry: development of environmentally friendly synthetic methodologies

“…Intermediate p-allyl-Ni II species have been proposed to be formed from electrogenerated Ni 0 -bipy complexes and the allyl substrates. 48,49 Allyl transfer from the ester to the carbonyl group of 16, followed by lactonisation of the hydroxy acid intermediate, occurred in a one-pot reaction. In conventional allylations, stoichiometric Ni 0 reactions with aldehydes involving (p-allyl)Ni II species have been reported, 50 but no example of allyl transfer or of lactone formation (as in Scheme 11) by conventional methods has been reported.…”