Copper-catalyzed asymmetric sulfoxidation of aryl benzyl and aryl alkyl sulfides, using aqueous hydrogen peroxide as the oxidant, has been investigated. A relationship between the steric effects of the sulfide substituents and the enantioselectivity of the oxidation has been observed, with up to 93% ee for 2-naphthylmethyl phenyl sulfoxide, in modest yield in this instance (up to 30%). The influence
Investigation of steric and electronic effects in the copper-catalysed asymmetric oxidation of sulfides
作者:Graham E. O'Mahony、Kevin S. Eccles、Robin E. Morrison、Alan Ford、Simon E. Lawrence、Anita R. Maguire
DOI:10.1016/j.tet.2013.08.063
日期:2013.11
in the copper-catalysed asymmetricoxidation of aryl benzyl, aryl alkyl and alkyl benzyl sulfides have been investigated. The presence of an aryl group directly attached to the sulfur is essential to afford sulfoxides with high enantioselectivities, with up to 97% ee for 2-naphthyl benzyl sulfoxide, the highest enantioselectivity achieved to date for copper-catalysed asymmetric sulfoxidation. In contrast
method is presented for the asymmetric oxidation of sulfides with H2O2, utilizing a pre-formed manganese complex. Just in the presence of a low catalytic amount of carboxylic acid (CA), a variety of sulfide substrates, including aryl alkyl, aryl benzyl and cyclic sulfides, reacted to form chiral sulfoxides in high yields (up to 95%) and excellent enantioselectivities (>99% ee) under mild conditions. Moreover
提出了一种利用预先形成的锰配合物,用H 2 O 2对硫化物进行不对称氧化的简便,环保的方法。仅在低催化量的羧酸(CA)存在下,各种硫化物底物(包括芳基烷基,芳基苄基和环状硫化物)就以高收率(高达95%)和出色的对映选择性反应形成手性亚砜( ee> 99%)。此外,该方法的实用性已经通过埃索美拉唑和阿苯达唑亚砜(ABZO)的合成得到证明。
Localized Partitioning of Enantiomers in Solid Samples of Sulfoxides: Importance of Sampling Method in Determination of Enantiopurity
作者:Aaran J. Flynn、Alan Ford、Anita R. Maguire
DOI:10.1021/acs.joc.0c01094
日期:2020.8.7
amorphous enantioenriched aryl benzyl sulfoxides in the solid state can lead to substantial variation in enantiopurities, even for sulfoxides which do not show detectable levels of self-disproportionation of enantiomers (SDE) during chromatography on an achiral stationary phase. The importance of preparation of representative samples of enantioenriched sulfoxides for chiral HPLC to enable reproducible