Chiral ligands sulfinyl groups

Chiral sulfoximines liganded to copper(II) give highly enantioselective vinylogous Mukaiyama-type aldol reactions under mild conditions.137 A chiral sulfinyl group has been used to achieve 1,5- and 1,6-asymmetric induction in Mukaiyama aldols, using Yb(OTf)3 catalysis.138... 

C. CHIRAL LIGANDS CONTAINING CHIRAL SULFINYL GROUPS... 

Chiral oxazoline ligands 24a,bearing a chiral sulfinyl group provided enantiose-lectivity of (5)-2 with 88% or 55% ee, respectively, in the Pd-catalyzed alkylation of 1 with dimethyl malonate using [Pd(7r-allyl)Cl]2, BSA, and KOAc in dichloromethane... 

C.ii. Ligands Bearing Sulfinyl Groups as Sole Chiral Sources... 

A chiral bis-sulfoxide ligand 28 has been developed as a new ligand bearing a sulfinyl group as a sole chiral source. ... 

However, in later work it was found that a non-chiral ligand could also be used— the enantioselectivity being created by the sulfinyl group (Fig. 50) [165-167]. Microwave radiation can be used to accelerate the reaction [168]. 

Among /1-thiosubstituted organophosphorus compounds bearing chiral groups, phosphono methyl thiazolines (Sect. 2.2.1, Scheme 8) and o-sulfanyl aryl phos-phonamides or phosphinoxides (Sect. 3.3, schemes 20 and 21) have already been mentioned. As a complement to this, some recent synthesis of non racemic /1-sulfinyl phosphines and phosphonates and thiazolidinyl phosphonates are reported below. Moreover, some chiral )8-thio-substituted phosphines have been used as metal ligands in asymmetric catalysis and are listed in Sect. 5.3. 

This chapter reports principally on studies with ruthenium chiral phosphine and chiral sulfoxide complexes and their use for catalytic hydrogenation. We have used the familiar diop ligand, [2R,3R-(—)-2,3-Oisopropylidene-2,3-dihydroxy-l,4-bis(diphenylphosphino) butane] (7) a related chiral chelating sulfoxide ligand dios, the bis(methyl sulfinyl)butane analog (21) (S,R S,S)-(+)-2-meth-ylbutyl methyl sulfoxide(MBMSO), chiral in the alkyl group and R-(+)-methyl para-tolyl sulfoxide(MPTSO), chiral at sulfur. Preliminary data on some corresponding Rh(I) complexes are presented also. 

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