794526-02-6Relevant articles and documents
The sulfinyl group as a remote chiral auxiliary in stereoselective conjugate additions of alkyl groups to α-methylidene carbonyl compounds initiated by Et3B/O2
Fernandez-Salas, Jose Antonio,Maestro, M. Carmen,Rodriguez-Fernandez, M. Mercedes,Garcia Ruano, Jose L.
, p. 1796 - 1804 (2013/04/23)
Reactions of α-[2-(p-tolylsulfinyl)phenyl] α-methylidene carbonyl compounds 1 and 2 with alkyl radicals generated from Et 3B/O2 and RI give, after protonation, β-alkyl derivatives with a high degree of control of the configuration at the α carbon. In the case of aldehyde 2, when further combined with allylation of the carbonyl group, a one-pot radical-addition/protonation/allylation sequence provides a highly stereoselective synthesis of compounds bearing two adjacent chiral centres. The stereochemical course of the reaction is controlled by the sulfinyl group acting as a remote chiral auxiliary, and this group can be easily removed with tBuLi. The sulfinyl group can be an efficient remote chiral auxiliary in the stereoselective radical addition to α-methylidene carbonyl compounds. Radicals were generated from alkyl iodides with Et 3B/O2. The stereocontrol comes from the formation of chelated complexes of the Lewis acid with the carbonyl and sulfinyl oxygen atoms. This process gives access to enantiopure compounds with chiral benzylic centres. Copyright
Synthesis of chiral ortho-(p-tolylsulfinyl) benzyl ketones
García Ruano, José L.,Alemán, José,Teresa Aranda,ángeles Fernández-Ibáez,Mercedes Rodríguez-Fernández,Carmen Maestro
, p. 10067 - 10075 (2007/10/03)
(S)-ortho-(p-Tolylsulfinyl)benzyl alkyl (and aryl) ketones 1a-e were prepared in good yields by reaction of esters or nitriles with the lithium benzyl carbanion derived from 2-(p-tolylsulfinyl) methylbenzene. α-Methylbenzyl ketones 2 were prepared as ca. 1:1 diastereoisomeric mixtures by methylation of the unsubstituted ketones 1 with NaH/MeI. The use of the ethylbenzene derivative as the starting material afforded complex mixtures. The obtention of pure (S,(S)S)-2 diastereoisomers could be attained in good yields by oxidation with PCC of the alcohols (epimeric mixtures at the hydroxylic carbon) obtained from reactions of aldehydes with the lithium carbanion derived from 2-(p-tolylsulfinyl)ethylbenzene. Graphical Abstract
