181268-49-5Relevant articles and documents
Stereoselective addition of organometallic reagents to N-(tosyl)vinylsulfoximines
Jackson, Richard F. W.,Briggs, Andrew D.,Brown, Paul A.,Clegg, William,Elsegood, Mark R. J.,Frampton, Christopher
, p. 1673 - 1682 (2007/10/03)
Treatment of N-(toluene-p-sulfonyl)vinylsulfoximines 3 with methyllithium at -78°C, followed by addition of chlorotrimethylsilane, results in the efficient formation of α-silyl vinylsulfoximines 6 in good to excellent yield. Nucleophilic addition of a range of simple alkyl and aryl organometallics (lithium, copper-lithium and Grignard reagents) occurs in variable yield to give the Michael adducts 8 with organolithium reagents most effective. The degree of stereoselectivity of each of the addition reactions was determined by 1H NMR of the desilylated products 9, and proved to be synthetically useful for compounds in which the starting α-silylvinylsulfoximines were branched at the γ-position, and also when phenylhthium was used as the nucleophile. The sense of stereoselectivity was determined in two cases by X-ray crystal structure analyses (of 9e and 9i). A one-pot process for the conversion of α-silylvinylsulfoximines 6 to α-substituted carboxylic acids 11 was developed, using an in situ phenylselenation-oxidation process following the initial conjugate addition. Use of enantiomerically pure starting materials allowed the assignment of configuration of two carboxylic acids (13e and 13h) by comparison with literature data, and hence indirectly of the relative stereochemistry of the initial Michael adducts 9e and 9h.
