Collect. Czech. Chem. Commun.
2007, 72, 985-995
https://doi.org/10.1135/cccc20070985
Stereoselective Methylation of 1-(Diphenylphosphanyl)-2-[(methoxycarbonyl)methyl]ferrocene. The Crystal Structures of the Methylated Ester and Its Palladium(II) Complex with an Auxiliary 2-[(Dimethylamino)methyl]phenyl Ligand.
Martin Lamač, Ivana Císařová and Petr Štěpnička*
Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic
Abstract
Treatment of racemic 1-(diphenylphosphanyl)-2-[(methoxycarbonyl)methyl]ferrocene successively with NaN(SiMe3)2 and methyl iodide affords the C-alkylated product, 1-(diphenylphosphanyl)-2-[1-(methoxycarbonyl)ethyl]ferrocene (6), as a mixture of diastereoisomers in ca. 10:1 ratio, from which the major (S,Rp/R,Sp)-diastereoisomer is easily isolated by crystallisation. (S,Rp/R,Sp)-6 reacts with [Pd(LNC)(MeCN)2]ClO4 (LNC = 2-[(dimethylamino-κN)- methyl]phenyl-κC1) to give the cationic bis-chelate complex (S,Rp/R,Sp)-[Pd(LNC)(6-κ2O,P)]- ClO4 (9). The structures of (S,Rp/R,Sp)-6 and 9 have been determined by single-crystal X-ray diffraction. Hydrolysis of ester 6 to the corresponding carboxylic acid proved to be difficult, being complicated by racemisation at the chiral carbon atom and oxidation of the phosphanyl group.
Keywords: Ferrocenes; Phosphanes; Esters; Alkylation; Chiral ligands; Palladium; Crystal structure determination.
References: 21 live references.
