STEREOSELECTIVE METHYLATION OF l-(DIPHENYLPHOSPHANYL)- 2-((METHOXYCARBONYL)METHYL)FERROCENE. THE CRYSTAL STRUCTURES OF THE METHYLATED ESTER AND ITS PALLADIUM(II) COMPLEX WITH AN AUXILIARY 2-((DIMETHYLAMINO)METHYL)PHENYLLIGAND.

摘要

Treatment of racemic l-(diphenylphosphanyl)-2-[(methoxycarbonyl)methyl]ferrocene successively with NaN(SiMe_3)_2 and methyl iodide affords the C-alkylated product, l-(diphenyl-phosphanyl)-2-[l-(methoxycarbonyl)ethyi]ferrocene (6), as a mixture of diastereoisomers in ca. 10:1 ratio, from which the major (S,R_p/R,S_p)-diastereoisomer is easily isolated by crystallisation. (S,R_p/R,S_p)-6 reacts with [Pd(L~(NC))(MeCN)_2]ClO_4 (L~(NC) = 2-[(dimethylamino-kappaN)-methyllphenyl-kappaC~1) to give the cationic bis-chelate complex (S,R_p/R,S_p)-[Pd(L~(NC))(6-Kappa~2O,P)]-C1O_4 (9). The structures of (S,R_p/R,S_p)-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.