148003-99-0Relevant academic research and scientific papers
Diastereoselectivity in the Preparation of β-Silyl Esters from αβ-Unsaturated Esters and Amides Attachhed to Chiral Auxiliaries
Fleming, Ian,Kindon, Nicolas D.
, p. 303 - 316 (2007/10/02)
The conjugate addition of the phenyldimethylsilyl-cuprate reagent to cinnamate and crotonate esters and amides 1 of various known chiral auxiliaries, a-e, is diastereoselective.The sense of diastereoselectivity of silyl-cuprate addition to the esters 1b-d, 8 and 9 is different from established precedent based on carbon-cuprates, but is normal for silyl-cuprate addition to the amide 1a, the imines 1e and 21, and the oxazolidine 6.The chiral auxiliary e gives the best results of those tested, and the silicon-containing group can be removed from the chiral auxiliary using alkoxide ion in aprotic media, making available β-silyl esters 27-29 of high enantiomeric excess, with recovery of the chiral auxiliary 30.
A Regiocontrolled and Stereocontrolled Synthesis of Allylsilanes from β-Silyl Enolates
Fleming, Ian,Gil, Salvador,Sarkar, Achintya K.,Schmidlin, Tibur
, p. 3351 - 3362 (2007/10/02)
The α-lithiated diphenylphosphine oxides 3 react with methyl iodide to give the phosphine oxides 4 and 5 in a ratio 3-4:1.The corresponding reaction with aldehydes gives all four diastereomeric alcohols 7-10, which are not suitable for the synthesis of allylsilanes by a Wittig-Horner reaction.The β-dimethyl(phenyl)silyl enolates 13-15 and 25-28 react with aldehydes to give aldol products with high diastereoselectivity.The benzyl and allyl ester groups can be cleaved from these aldols to give the acids 16-18 and 29-32.The acids, in turn, can be induced to undergo dec arboxylative elimination stereospecifically either in a syn or an anti sense to give the allylsilanes 19, 20, 23, 24, 33, 34 and 39-41.A similar series of reactions can be carried out with the β-trimethylsilyl enolates 45 and 46 giving the allylsilanes 49, 50, 53 and 54.
Diastereoselective Aldol Reactions of β-Silylenolates: A New Regiocontrolled Synthesis of Allylsilanes
Fleming, Ian,Sarkar, Achintya K.
, p. 1199 - 1201 (2007/10/02)
Allylsilanes are prepared stereospecifically trans (10) or cis (12) and with complete regiocontrol by decarboxylative elimination of the β-hydroxy acids (9).
