Asymmetric synthesis of organophosphorus compounds

Enantiomerically pure 2-[2-(diphenylphosphino)aryl]oxazolines are readily prepared from 2-bromobenzonitrile by transmetalation with BuLi, subsequent reaction with chloro-diphenylphosphine and conversion of the resulting phosphinoaryl nitrile to the oxazoline by treatment with a chiral amino alcohol in the presence of ZnCl2. An alternative synthesis is based on the orthometalation of 2-aryloxazolines followed by reaction with chlorodiphenylphosphine.

Synthesis of chiral (phosphinoaryl)oxazolines, a versatile class of ligands for asymmetric catalysis

The Structures of Tris(8-dimethylamino-1-naphthyl)phosphane and Tris[2-(dimethylaminomethyl)phenyl]phosphane - Crystallographic Evidence of 7-coordinate Phosphorus

Novel P,N chelating ligands with three stereogenic centres in positions α to the donor atoms have been prepared in good yields and high enantiomeric purity by a series of reactions beginning with either (R)- or (S)-1-phenylethylamine These isomers were first lithiated with tBuLi and converted into aminophosphanes 3a by treatment with (Et2N)2PCl They were transformed into the enantiomeric primary phosphanes 4 by quantitative solvolysis with ethanol to give the phosphonous acid esters 3b and subsequent reduction with LiAlH4 Stepwise treatment of 4 with nBuLi and the cyclic sulfate of (S,S)-2,5-hexanediol gave the isomeric tertiary phosphanes (R,RR)-5 and (S,RR)-5 Treatment of the aminophosphane (R)-3a with (R)-2,2′-binaphthol yielded the aminophosphonite (R,R)-6 in high yields Cationic (COD)Rh complexes of 5 were prepared by treatment with [Rh(COD)Cl]2, the PF6− salts 7a being isolated Analogous (2,5-norbornadiene)Rh complexes 7b were prepared similarly The chelate nature of the P,N ligands in these salts is indicated by their NMR spectra in solution and is confirmed by the crystal structures of (R,RR)-7a and (S,RR)-7a With the exception of (S,RR)-7a, the complexes 7a and 7b are shown to catalyse the asymmetric hydrogenation of methyl acetamidocinnamate at room temperature Differences in the catalytic activity of the complexes are related to the different dynamic behaviour detected by the 1H EXSY spectra for the COD ligands of 7a (© Wiley-VCH Verlag GmbH & Co KGaA, 69451 Weinheim, Germany, 2003)

Novel P,N Ligands Derived from (R)‐ and (S)‐1‐Phenylethylamine with (2R,5R)‐2,5‐Dimethylphospholanyl Groups (DuPHAMIN) for Asymmetric Catalysis

Die Strukturen von Tris(8‐dimethylamino‐1‐naphthyl)phosphan und Tris[2‐(dimethylaminomethyl)phenyl]phosphan: der kristallographische Nachweis von siebenfach koordiniertem Phosphor

Schlusselreaktion fur die Synthese der im Titel genannten Verbindungstypen ist die ortho-Lithiierung von R-bzw. S-1-Phenyl-ethyl-N,N-dimethylamin. Mit geeigneten Verbindungen, z.B. R,NEt2,PCl (R=Me, Ph) wird nach (1) in die ortho-Position zur Seiteniette der Phosphorrest eingefuhrt. Durch Grignardierung der Verbindungen 1 und 2 erhalt man die tertiaren Phosphine 3 bis 6. Uber die Phosphinoxide 7 bis 10 gelingt die Trennung in die Diastereomeren, die mit PhSiH3 in die tertiaren Phosphine 3 bis 6 mit unbekannter Konfiguration am Phosphor uberfuhrt werden. Nach (3a) und (3b) erhalt man die bis-chiralen Triarylphosphine 12 bis 15, die jedoch nicht in die Diastereomeren aufgetrennt werden konnten. Die Bis-N,P-Chelate 16, 17, 18 und 21 sind nach (4) und (5) zuganglich. Nur die Verbindungen 17 und 18 konnten in die Diastereomeren mit unbekannter Konfiguration am Phosphor aufgetrennt werden. For the synthesis of the title compounds the key reaction is the ortho-lithiation of R-rsp. S-1-phenyl-ethyl-N,N-d...

Phosphororganische verbindungen 1071 die synthese zweifach chiraler tertiärer phosphine und von bis-n,p-chelaten als mögliche chelatliganden für homogenkatalysen

L. Horner

Papers

Phosphororganische verbindungen 1071 die synthese zweifach chiraler tertiärer phosphine und von bis-n,p-chelaten als mögliche chelatliganden für homogenkatalysen