1459-00-3Relevant articles and documents
Chemoselective Homologation-Deoxygenation Strategy Enabling the Direct Conversion of Carbonyls into (n+1)-Halomethyl-Alkanes
Citarella, Andrea,Holzer, Wolfgang,Ielo, Laura,Langer, Thierry,Miele, Margherita,Pace, Vittorio,Urban, Ernst,Zehl, Martin
supporting information, p. 7629 - 7634 (2020/10/12)
The sequential installation of a carbenoid and a hydride into a carbonyl, furnishing halomethyl alkyl derivatives, is reported. Despite the employment of carbenoids as nucleophiles in reactions with carbon-centered electrophiles, sp3-type alkyl halides remain elusive materials for selective one-carbon homologations. Our tactic levers on using carbonyls as starting materials and enables uniformly high yields and chemocontrol. The tactic is flexible and is not limited to carbenoids. Also, diverse carbanion-like species can act as nucleophiles, thus making it of general applicability.
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.
Hydroalumination of alkenes by the LiAlH4*3AlBr3 system
Gorobets, E. V.,Shitikova, O. V.,Lomakina, S. I.,Tolstikov, G. A.,Kuchin, A. V.
, p. 1573 - 1578 (2007/10/02)
The hydroalumination of a series of alkenes and some fused aromatic hydrocarbons by the LiAlH4*3AlBr3 system in low-polar solvents was studied.Alkenes with mono-, di-, tri-, and tetraalkyl substituted, mono- and diaryl substituted double bonds and anthracene react at room temperature to give the corresponding dibromoaluminoalkanes in high yields.Benzylidenefluorene, tetraphenylethylene, naphthalene, and phenanthrene do not undergo hydroalumination under these conditions.Camphene, bicyclooct-2-ene, and norbornene afford the corresponding organoaluminum compounds with high stereoselectivity.Oxidation and halo- and acyldemetallation of the resulting alkyl- and arylalanes were carried out.
