Leaving groups chiral sulfoxide

Stereospecific effects on both nonleaving group (1,2-diaminocyclohexane) and leaving group (chiral sulfoxide) have been shown for both biological activity and DNA binding. 

A chiral sulfoxide can be used as a leaving group for the asymmetric inducdon via addidon-eliminadonprocess. 5-Lactam enolates are converted into the corresponding nitroalkenes subsdnited with lactams fEq. 4.101. ... 

A similar asymmetric nitroolefination reaction has been described that uses an optically active / -nitro-a,/ -unsaturated sulfoxide, e.g., 2-nitro-1-[(/ )-2-phenylpropylsulfmyl]cyclohexene, where the chiral sulfoxide moiety functions as a leaving group. Condensation oflactam enolates with this sulfoxide affords substituted lactams with high enantiomeric excesses and good yields27. 

Chiral sulfoxides are useful intermediates in asymmetric synthesis. A number of methods for their preparation were developed in the last decade. An interesting displacement of dimethylphosphonylmethyl moiety, a carbon leaving group, from sulfur by Grignard reagents was used to obtain enantiomerically purep-tolyl sulfoxides.3 4 Optically pure methyl 4-bromophenyl sulfinate was subjected to a one-pot sequence yielding unsymmetrical dialkyl sulfoxides in 60-97% yield and >98% ee. A simple one-pot synthesis of chiral sulfoxides from norephedrine-derived... 

In most cases, the sulfoxides produced after the asymmetric transformation are reduced with sodium or aluminium amalgam, or Raney nickel. The sulfoxide may also be reduced by LiAffl into a sulfide, winch after quaternarization becomes a leaving group [474], If the carbon skeleton of the substrate bears appropriate substituents, the sulfoxide can suffer [2,3] sigmatropic rearrangements [497, 498] or Pummerer rearrangements. In all these types of applications, the chiral auxiliary is never recovered. 

Chiral sulfoxides have recently been proposed as leaving groups in the synthesis of chiral 2-isopropoxycarbonyl or dimethylamido-1,1 -binaphthyls [495],... 

Eliminations. When functionalized silanes in which a potential leaving group is attached to a /3-atom or to a vinylogously related atom are treated with TBAF, fragmentation ensues. New uses of this process are preparations of 2,3-dimethylene-2,3-dihydrothiophene," substituted 1,2,3-butatrienes, chiral allylic alcohols, and a-fluoroketones. The precursors for the allylic alcohols are the alkylation products (with aldehydes) of 2-(trimethylsilyl)ethyl sulfoxides, and those for the fluoroketones are 1-silyl-l-hydroxymethyloxiranes. 

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