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
Prochiral Diheteroaryl Sulfoxides and Their Reactions with (<i>S</i>)-Li<sub>2</sub>-BINOLate-Activated Diisobutylmagnesium
作者:Simon Ruppenthal、Reinhard Brückner
DOI:10.1002/ejoc.201701309
日期:2018.1.10
symmetric – i.e. prochiral – diheteroaryl sulfoxides. The latter were treated with a 0.5- or 1.2-fold molar amount of 5:4 mixtures of dilithium (S)-BINOLate and diisobutylmagnesium. This allowed five asymmetricsulfoxide/magnesium exchange reactions to occur. They delivered asymmetricsulfoxides in up to 77 % yield and with up to 88 % ee. Surprisingly, four related diheteroaryl sulfoxides, bis(2-pyridyl)
5 元环杂环被α-锂化或α-镁化,以便它们攻击SOCl2 或SO(OMe)2,形成对称的——即前手性——二杂芳基亚砜。后者用0.5-或1.2-倍摩尔量的5:4二锂(S)-BINOLate和二异丁基镁的混合物处理。这允许发生五个不对称的亚砜/镁交换反应。他们以高达 77% 的产率和高达 88% 的 ee 提供不对称亚砜。令人惊讶的是,四种相关的二杂芳基亚砜、双(2-吡啶基)亚砜和双(3-吡啶基)亚砜不适合这种交换,而是分解了。
Chiral<i>N</i>,<i>N</i>′-dioxide–iron(<scp>iii</scp>)-catalyzed asymmetric sulfoxidation with hydrogen peroxide
enantioselective sulfoxidation of various sulfides has been achieved by a N,N'-dioxide-iron(iii) complex with 35% aq. H2O2 as the oxidant. The utility of the current method was demonstrated by asymmetric gram-scale synthesis of drug molecule (R)-modafinil. Moreover, a possible working mode was provided to elucidate the chiral induction.
Enantioselective inclusion of chiral alkyl aryl sulfoxides in a supramolecular helical channel consisting of an enantiopure 1,2-amino alcohol and an achiral carboxylic acid
The enantio selective clathrate formation of alkyl aryl sulfoxides 4 was achieved with dissymmetric one-dimensional helical channels created in two-component hosts consisting of (1R,2S)-2-amino-1,2-diphenylethanol 1 and an achiral carboxylic acid, p-tert-butylbenzoic acid 2, or 2-anthraquinonecarboxylic acid 3. X-ray crystallographic analyses showed that the host framework (1R,2S)-1.3 in the single crystal of a clathrate with methyl p-methylphenyl sulfoxide 4n [(1R,2S)-1.3.4n (single)] maintained a supramolecular helical array as those of the solvent-included single crystals (1R,2S)-1.3-EtOH(single) and (1R,2S)-1-3-H2O.THF(single), while the guest 4n molecules were highly disordered. Moreover, the X-ray powder diffraction pattern of (1R,2S)-1-3-4n(clathrate) obtained through the clathrate formation demonstrated that the molecular arrangements of (1R,2S)-1, 3, and 4n were not the same as those which appeared in (1R,2S)-1.3.4n(single); the channel was enlarged. These results are consistently explained by assuming the dynamic motion of the framework (1R,2S)-1-3 to achieve widely applicable clathrate formation. (c) 2007 Elsevier Ltd. All rights reserved.