Jürgen F. K. Müller

X-Ray Structure of a Heterochiral, Sulfoximine-Stabilized Dilithiomethane Derivative.

A distorted Li(6)O octahedron in the center and four geminal dilithiated sulfoximine units characterize a tetrameric aggregate of the chiral sulfoximine-stabilized dilithiomethane derivative 3, a previously unknown reaction intermediate in asymmetric dianion chemistry. A comparison with the crystal structure of the monolithiated parent 2, formed by the treatment of 1 with nBuLi, allows a rationalization of the second lithiation.

Cu(I)-catalyzed sulfoximination

Abstract The reaction of PhINTs with sulfoxides in the presence of catalytic amounts of CuOTf afforded the corresponding N-tosylsulfoximines in high yield. The use of enantiomerically pure sulfoxides allowed stereoselective access to N-tosylsulfoximines with complete retention of configuration at sulfur.

β-Hydroxy sulfoximines as catalysts for the enantioselective alkylation of aldehydes

Optically active β-hydroxy sulfoximines are catalysts for the enantioselective ethyl transfer from diethylzinc to aldehydes affording secondary alcohols with high enantioselectivity; the structure of a dimeric zinc alkoxide has been determined by X-ray diffraction analysis.

Crystallographic studies of {η3-1,3-dimethylallyl}{2-[2′-diphenylphosphino) phenyl]oxazoline-P,N} palladium(II) hexafluorophosphates complexes complemented by 1H NMR investigations

Abstract Palladium(II) η 3 -1,3-dimethylallyl complexes 1–4 with chiral and non-chiral substituted 2-[2′-(diphenylphosphino)phenyl]oxazolines as ligands were prepared and characterized by X-ray diffraction studies. The determination of the corresponding solution structures were carried out for 1–4 and the complexes 5–6 by 1D and 2D NMR measurements. X-ray and NMR studies equally confirm that the main isomers of the complexes 1–3 preferentially adopt the exo-syn-syn configuration, which is in contrast to 4 where the main isomers dopts the exo-syn-anti configuration in solution and in the solid state.

Spectroscopic studies on the β-hydroxysulfoximine-catalyzed enantioselective alkylation of aldehydes

Abstract The asymmetric β-hydroxysulfoximine-catalyzed alkyl transfer from diethylzinc to benzaldehyde has been studied by NMR spectroscopy.

Chiral Dilithiomethane Derivatives: Structure Determination and Application in Stereoselective Reactions

The synthesis and X-ray analysis of chiral dilithiomethane analogues derived from sulfoximines are presented. The structures of the sulfoximine-stabilised mono- and dilithio salts have been compared and allow a rationalization of the second lithiation. Organophosphorus-based dilithiomethane derivatives are also structurally described. The gas-phase structures of N,S,S-trimethylsulfoximine 19 and of its mono- and dilithiated isomers 20–21 were calculated by ab initio methods employing different levels of theory. For an application in asymmetric synthesis, the dilithiation of (N-methyl)-S-ethyl-S-phenylsulfoximine (11) afforded a chiral dinucleophile that undergoes highly regio- and stereoselective alkylation reactions with electrophiles. The transmetallation of a chiral dilithiomethane reagent such as 14 with ClTi(OiPr)3 followed by addition of an aldehyde, constitutes a simple one-pot process for the formation of (E)-alkenylsulfoximines with excellent diastereoselectivity.

A simple protocol for the synthesis of chiral bidentate imidodiphosphoric tetramide ligands: application in the metal-free asymmetric allylation of aldehydes

Abstract The reaction of a series of chiral phosphorus triamides with BuLi and subsequent addition of a phosphoroxychloride diamide afforded the corresponding imidodiphosphoric tetramides in high yield. The use of enantiomerically pure diamides allowed access to bidentate imidodiphosphoric tetramides without loss of optical purity. These bidentate ligands have been used successfully to catalyze the addition of allyltrichlorosilane to aldehydes in an enantioselective fashion up to 60% ee.

AN AB INITIO STUDY ON DILITHIOSULFOXIMINES

Abstract The gas-phase structures of the dilithiosalts of (N-methyl)dimethylsulfoximine 1 were calculated by ab initio methods employing different levels of theory (HF, MP2, B3LYP and CBS). Three low-energy structures were found, with the 1,3-dilithiosulfoximine 2, a metalla spiro structure, as the most stable isomer. The second minimum 3 contains a α,α dilithio motif forming two four-membered rings with the heteroatoms on sulfur, whereas isomer 4 shows one lithium coordinating to the two anionic carbon atoms and the other to the two heteroatoms bound to the sulfur. The values of the relative energies of the compounds 3 and 4 are 1–5 kcal mol−1 higher in energy than that of 2 and fairly close to one another depending on the applied level of theory. A comparison between DFT and CBS-Q calculations is made and reveals no significant discrepancies in the structures. The monolithium and lithium-free dianions 2a,b−–4a,b−, 22−–42− and their complexation energies to the lithium cations were also calculated. NBO analyses were carried out to reveal donor–acceptor interactions in these dilithio salts.

KRISTALLSTRUKTUR EINES HETEROCHIRALEN SULFOXIMIN-STABILISIERTEN DILITHIOMETHAN-DERIVATS

Ein verzerrtes Li6O-Oktaeder im Zentrum und vier geminal dilithiierte Sulfoximin-Einheiten charakterisieren die Kristallstruktur eines tetrameren Aggregats des chiralen Sulfoximin-stabilisierten Dilithiomethanderivats 3, eines zuvor unbekannten Reaktionsintermediats in der Chemie asymmetrischer Dianionen. Ein Vergleich mit der Struktur der monolithiierten Vorstufe 2, die aus 1 durch Umsetzung mit nBuLi zuganglich ist, liefert eine mogliche Erklarung fur die zweite Lithiierung.

Reaktionen an komplexgebundenen liganden: XXXVI. Synthese und oxidationsverhalten von M(CO)5-komplexen (M = Cr, Mo, W) mit amin- und benzochinondiimin-liganden☆

Abstract The oxidation of yellow Cr(CO) 5 NH 2 R complexes (NH 2 R = aniline, m -toluidine, 3,5-xylidine, m -anisidine) with Pbac 4 gives deep blue to deep purple coloured compounds, which have been identified as the respective [Cr(CO) 5 ( N -phenyl-1,4-benzochinon-diimine)] complexes. Oxidation of the p -phenylenediamine complex yields [(OC) 5 CrHNC 6 H 4 NHCr(CO) 5 ], which is also deep blue. The binuclear blue complex [{Cr(CO) 5 } 2 HNC 6 H 4 NC 6 H 5 ] is obtained by treating Cr(CO) 5 THF with the free ligand in THF/hexane; it dissociates rapidly in acetone to form [Cr(CO) 5 HNC 6 H 4 NC 6 H 5 ] and Cr(CO) 5 . Analogous Mo(CO) 5 and W(CO) 5 complexes could not be obtained. The oxidation of [W(CO) 5 ( m -anisidine)] by I 2 yields [W(CO) 4 I] 2 . All the compounds were characterized by spectroscopic methods as well as by elemental analysis.