59021-31-7Relevant articles and documents
Reaction of acylsilanes with α-sulfinyl carbanions: Regioselective synthesis of silyl enol ethers
Honda, Mitsunori,Nakajima, Tadashi,Okada, Maiko,Yamaguchi, Keita,Suda, Mitsuhiro,Kunimoto, Ko-Ki,Segi, Masahito
experimental part, p. 3740 - 3742 (2011/08/06)
The reaction of acylsilanes with α-sulfinyl carbanions such as α-lithioalkyl sulfoxide is described. The reaction proceeds to give silyl enol ethers preferentially through the initial formation of the α-silyl alkoxide intermediates. In particular, the products derived from enolizable acylsilanes were the regio-defined silyl enol ethers that cannot be obtained by usual enolization of the corresponding unsymmetrical ketones with base.
Reaction of acylsilanes with sulfur ylides. Selective formation of silyl enol ethers or β-ketosilanes
Nakajima, Tadashi,Segi, Masahito,Sugimoto, Fumitosi,Hioki, Reiko,Yokota, Seiko,Miyashita, Kiyoshi
, p. 8343 - 8358 (2007/10/02)
The reaction of acylsilanes with sulfur ylides in THF results in the formation of the corresponding silyl enol ethers or β-ketosilanes. The relative ratio of these products varies with the ylide conditions and the stability of ylide used. It is noteworthy that silyl enol ethers were formed under the salt-free ylide conditions, and that β-ketosilanes were yielded in the presence of soluble inorganic salts in THF, selectively. The formation of both products would be interpreted in terms of the anionotropic and cationotropic rearrangements of silyl group in the reaction intermediate.
Chemistry of oxaziridines. 14. Asymmetric oxidation of ketone enolates using enantiomerically pure (camphorylsulfonyl)oxaziridine
Davis, Franklin A.,Sheppard, Aurelia C.,Chen, Bang-Chi,Haque, M. Serajul
, p. 6679 - 6690 (2007/10/02)
The reagent-controlled asymmetric oxidation of tri- and tetrasubstituted ketone enolate anions 4 and 8 by enantiomerically pure (camphorylsulfonyl)oxaziridine 2 has been investigated. The stereoselectivities for oxidation of trisubstituted enolates 4a-d are good to excellent, 60-95% ee, while those for tetrasubstituted enolates 4e and 8 are lower; i.e., 21-30% ee. Isolated chemical yields for both types of enolate anions are good to excellent. The sodium enolate anions of 4a-d, which could be oxidized at -78°C, gave both higher yields and stereoselectivities than the corresponding lithium or zinc enolates, which required warming to higher temperatures for complete oxidation. The presence of HMPA generally had a deleterious effect on the stereoinduction. However, for oxidation of (E)- and (Z)-4d the highest ee's were observed in the presence of this additive. Investigation of the stereoselective trends reveals that the enolate substitution pattern and the enolate solution structure are the most important stereocontrol elements. The role that the enolate geometry has in the stereoinduction is less clear although Z enolates seem to exhibit higher stereoselectivities than the E enolates. The results obtained in this study have been formulated into a mechanistic rational involving an SN2-type substitution of the enolate anion on oxaziridine 2 via an "open" transition state.
