Asymmetric electrochemical oxidation of 1,2-diols, aminoalcohols, and aminoaldehydes in the presence of chiral copper catalyst

Abstract

Asymmetric oxidation of 1,2-diols, aminoalcohols and aminoaldehydes in the presence of copper(II) triflate and (R,R)-Ph-BOX, was accomplished by electrochemical method using Bras a mediator. This oxidation was applicable to kinetic resolution of racemic cis-cycloalkane-1,2-diols, aminoalcohols and aminoaldehydes to afford optically active compounds with good to high enantioselectivity.

Effecient Kinetic Resolution of Racemic Amino Aldehydes by Oxidation with N‐Iodosuccinimide

“…We believe that the high selectivity was obtained because of the asymmetric oxidation of aminoaldehydes 1 and 4 associated with the chiral copper catalyst was considerably faster than that of the acid catalyzed acetalization of their noncoordinated counterparts. In our previous study on oxidative kinetic resolution, [9] bases performed an important role of neutralizing generated HX to accelerate the reaction. However, here the oxidative kinetic resolution without any base improved the yield of the methyl esters (2 and 5) and the HX generated acted as a catalyst for the transformation of noncoordinated amino aldehydes.…”

Asymmetric Electrochemical Catalysis

“…In 2008, Onomura and colleagues realized an electro-oxidative resolution of as eries of diols (Scheme 18) catalyzed by a chiral Cu-18 b complex. [40] The reaction afforded a-hydroxyl ketones with good enantioselectivity.I nt he proposed catalytic cycle, chiral induction was achieved by bidentate coordination of diols with copper.T he anode-generated Br + served as the direct oxidant and the oxidationp roceeded througha nE 2type elimination mechanism assisted by methoxide generated at the cathode to afford the chiral ketones.Asimilarp rocess could also be applied to the kinetic resolutiono fa minoalcohols 18 c to 18 d and aminoaldehydes 18 e to 18 f.…”

“…In 2008, Onomura and colleagues realized an electro‐oxidative resolution of a series of diols (Scheme ) catalyzed by a chiral Cu‐ 18 b complex . The reaction afforded α‐hydroxyl ketones with good enantioselectivity.…”

Chiral Cu(II) salen complexes catalyzed aerobic oxidative biaryl coupling-probing the reaction by EPR

“…Copper(II), an EPR active metal ion, has been used in several asymmetric oxidation reactions [10][11][12][13][14][15][16][17][18]. Use of oxygen present in air as oxidizing agent is gaining attention by being abundant and cost effective [19].…”