abstracts - Институт катализа им. Г.К. Борескова

OP-II-15RECENT ADVANCES IN METAL CATALYZED ASYMMETRICSULFOXIDATIONSBryliakov K.P., Nuzhdin A.L., Talsi E.P.Boreskov Institute of Catalysis, SB RAS, Novosibirsk, RussiaE-mail: bryliako@catalysis.ruIn the past two decades, chiral sulfoxides have been finding increasing use, reflecting thegrowing interest both in convenient auxiliaries in asymmetric synthesis and products withbiological properties containing a chiral sulfinyl group. Until now, modified Sharplesssystems (based on Ti(Oi-Pr) 4 /diethyl tartrate combinations) have been regarded as the mosteffective sulfoxidation systems. However, they suffer from low turnover numbers(10-20 mol.-% of the catalyst required), low chemoselectivity and the need in relativelyexpensive alkylhydroperoxides as oxidants. In this paper, we describe novel routes to attainchiral sulfoxides via catalytic oxidation reactions.Recently, we have proposed a [(salen)Fe III Cl] based catalytic system for stereoselectiveoxidation of alkyl aryl sulfides [1].PhPhR S complex 1OR' RR'S*=OClPhIO (1.1 eq.),solvent up to 62% eeHHNNFe O(R,R)-1aHBHim64HN NFeO OCl(S,S)-1bHim64The catalytically active species has been detected by 1 H NMR at low temperature (-20 to0 °C). After shaking of complex 2 with PhIO in CDCl 3 upon cooling, formation of a newFe(III) complex is observed, although no PhI can be seen by 1 H NMR. Thus, the intermediateis apparently a iodosylbenzene-iron(III)(salen) complex. Its concentration decreases afteraddition of sulfides and can be restored by the addition of extra PhIO. The catalytic cycle forFe III (salen) catalyzed sulfide oxidation has been proposed.RS*OR'+ PhIFe III (salen*)PhIORSR'(salen*)Fe III -OIPhAnother catalytic system to be reported is based on titanium(IV) complexes withtridentate Schiff base ligands derived from chiral aminoalcohols [2]. It has been found to be218