The preparation of both diastereomeric derivatives of 3-(diphenylphosphany1)pyrrolidine with chiral (tetrahydrofuran-2-y1)methyl and [ (N-neopentyl)~iyrrolidin-2-yl]methyl groups as substituents on the pyrrolidine nitrogen atom and of (2S,4S) -l-benzyl-4-(diphenylphosphanyl)-2-(methoxymethy1)pyrrolidine is reported. [3S,P(RS)]-3-(phenylphosphanyl)pyrrolidine, bearing an additional chiral center on phosphorus, is the starting material for the preparation of phosphancs, in which one phenyl group of the PPh2 moiety is substituted by an 2-methoxyphenyl (L An) or 2,4,6-trimethoxyphenyl (= TMP) group. PdIz complexes of these ligands were separated into diastereomers by chromatography on silica gel columns. The structural chemistry of these novel phosphane diastereomers and their PdIa complexes is investigated by X-ray crystallography and NMR. At the P,Ncoordinated palladium center displacement of an iodide anion is found for P,N,N' ligands only. In the nickel complex catalysed cross-coupling reaction, yielding 3-phenyl-l-butene, we obtain the highest enantioselectivities in the case of simple l-alkyl-3-(diphenylphosphanyl)pyrrolidine ligands. The enantioselectivity obtained with diastereomeric dcrivatives, bearing additional ether or amine ligating sites is mainly determined by the chiral center in 3-position of the 3-(phosphany1)pyrrolidine part of these ligands. Optimisation of enantioselcctivity with these iigands can be carried out by a variation of the ligand to nickel ratio and by the choice of the vinyl halide used as starting compound. The catalytic cycle must contain at least one catalytically active species, bearing more than one 1kiminoalkylphosphane ligand.Carbon -carbon bond formation by cross-coupling of main group organometallics with carbon electrophiles catalysed by transition metal complexes is a valuable tool in organic chemistry"]. The cross-coupling of vinyl halides l a , l b with Grignard compound 2a preparcd from raccmic 1-chloro-1-phenylethane yields 3-phenyl-1 -butene (3)C2s31 (cf. Scheme 1). The generally accepted catalytic cycle of Grignard cross-coupling catalysid2] involves oxidative addition of a vinyl halide to a nickel(0) complex, transmetallation from the Grignard compound and reductive elimination of 3-phcnyl-1 -butem (3) regenerating thc nickel(0) complcx. The cross-coupling reaction using achiral nickel monophosphane (NILL,) coinplexes141 as catalysts has been investigated by Yamamotolsl. Thermodynamically more stable NiL2 complexes with tmns-coordinated phosphane ligands have to be isoinerised by associative mechanisms to the cis complexes before reductive elimination can occur. This truns to cis isomerisation can be promoted by the coordination of l'urther phosphane ligands or by transmetallation steps. Reductive elimination from the resulting NIL-, complcx in which alkyl groups arc cis-oriented may also be induced by coordination of further phosphane ligandd51.In the asymmetric version of this cross-coupling reaction enantioselectioii can take place cither during reductive elimina...
