126338-34-9Relevant academic research and scientific papers
Mechanistic and synthetic aspects of stereoselective reactions of lithium derivatives of chiral phosphine oxides: X-ray crystal structure of (1R*,2S*,1′S*,2′R*)-1-(1′- diphenylphosphinoyl-2'-phenylpropyl)-2-phenylsulfanylcyclohexan-1-ol
Gueguen, Catherine,O'Brien, Peter,Powell, Harold R.,Raithby, Paul R.,Warren, Stuart
, p. 3405 - 3417 (2007/10/03)
Lithiation of four different chiral phosphine oxides and reaction with seven different electrophiles has been carried out in order to discover what factors govern the sense and degree of asymmetric induction imparted by the resident chiral centre. Provided the groups at the chiral centre are significantly different in steric size (e.g. Ph and Me) and ketones, esters or Me3SiCl are used as the electrophile, surprisingly high levels of syn-diastereoselectivity are observed. Reactions with benzaldehyde or methyl iodide proved to be rather unselective. The stereochemistry of the reaction of lithiated 1-diphenylphosphinoyl-2-phenylpropane 9 with cyclohexanone was elucidated by conversion into(1R*,2S*,1′S*,2′R*)-1-(1′- diphenylphosphinoyl-2′-phenylpropyl)-2-phenylsulfanylcyclohexan-1-ol syn,syn,anti-39 and subsequent X-ray crystal structure analysis. The stereochemistry of the remainder of the compounds were determined by analogy and by using a reliable 13C NMR spectroscopy 3JPC coupling constant correlation. A detailed (and potentially general) mechanistic interpretation of the results which combines knowledge of the structure and configurational stability of lithiated phosphine oxides is discussed. In particular, it is suggested that a dynamic kinetic diastereoselection of rapidly equilibrating diastereomeric lithiated phosphine oxides explains the observed high levels of stereocontrol; a tentative transition state model is proposed to explain the syn-selectivity. Finally, the use of one of the addition products in the concise and stereoselective synthesis of an alkene with 1,4-disposed chiral centres is described.
Highly stereoselective hydroxy-alkylation, silylation and alkylation reactions of lithium derivatives of chiral phosphine oxides
Gueguen, Catherine,Mitchell, Helen J.,O'Brien, Peter,Warren, Stuart
, p. 7461 - 7464 (2007/10/03)
Reactions of lithium derivatives of chiral phosphine oxides with ketones (e.g. cyclohexanone, cyclobutanone, valerophenone) and Me3SiCl proceed with excellent levels of syn selectivity. In contrast, reactions with methyl iodide are moderately anti selective and those with aldehydes show no selectivity whatsoever.
Chiral phosphine oxides and chiral esters in stereoselective intermolecular acylation reactions of phosphine oxides
Cavalla, David,Gueguen, Catherine,Nelson, Adam,O'Brien, Peter,Russell, Matthew G.,Warren, Stuart
, p. 7465 - 7468 (2007/10/03)
Single diastereomers of β-keto phosphine oxides have been generated from intermolecular acylation of phosphine oxides using either chiral esters or chiral phosphine oxides. In some cases, reduction of the ketone products was not affected by the presence of extra chiral centres. Some mechanistic points of interest in the acylation reactions are discussed.
