Asymmetric Induction on the Reaction of Prochiral Olefins with Chloro-l-aminocarboxylato-η2-ethyleneplatinum(II)

Addition of a large excess of trans-2-butene (tbn) or 2-methyl-2-butene (mbn) to an acetone solution of cis- or trans(N, ethylene)[PtCl(l-am)(C2H4)] (l-am, 9 kinds of l-aminocarboxylate) gave first increase and then gradual decrease in CD strength in the region 26500 cm−1. The kinetic optical yield amounted to 53% whereas that at the equilibrated state was much less (up to 27% for cis(N, olefin) complexes and 6 to 12% for trans complexes), trans-2-Butene gives larger yields than mbn. Kinetic analysis of the growth and decay curve of the CD strength disclosed that the first fast increase in CD reflects the greater rate of substitution of the prochiral olefins for ethylene in S-configuration than that in R-configuration. The second step seems to involve the exchange of coordinated tbn or mbn catalyzed by ethylene which was made free in the first step. The mechanism of asymmetric induction has been discussed from both steric and electronic viewpoints. Asymmetry of the coordinated nitrogen seems to give a dominating effect.