The prochiral peroxometallacyclic ketenyl platinum complex [(PPh3)2 CO] (1) reacts with (S)-(−)-α-methylbenzylamine to give the diastereomeric amidic derivatives, 2. One of the two possible diastereomers, 2a, has been obtained pure and the absolute configuration at the carbon atom σ-bonded to the metal is inferred from its CD spectrum. Compound 2a has been used to oxidize the chiral racemic phosphine (RS)-PPhCyPr using a molar ratio, PPhCyPr 2a = 2: 1. The reaction products contains an enantiomeric excess of (S)-(−)-OPPhCyPr whereas unreacted PPhCyPr shows the prevalent (S) configuration, indicating that the reaction occurred with asymmetric induction. These findings are rationalized by a mechanism based on the coordination to the metal of PPhCyPr mainly in the (R) configuration, followed by an intramolecular oxidation by the peroxide moiety.
Stereochemical pattern of phosphine oxidation by a peroxometallacyclic platinum complex. Evidence of an intramolecular process
PANDOLFO, LUCIANO;
1994
Abstract
The prochiral peroxometallacyclic ketenyl platinum complex [(PPh3)2 CO] (1) reacts with (S)-(−)-α-methylbenzylamine to give the diastereomeric amidic derivatives, 2. One of the two possible diastereomers, 2a, has been obtained pure and the absolute configuration at the carbon atom σ-bonded to the metal is inferred from its CD spectrum. Compound 2a has been used to oxidize the chiral racemic phosphine (RS)-PPhCyPr using a molar ratio, PPhCyPr 2a = 2: 1. The reaction products contains an enantiomeric excess of (S)-(−)-OPPhCyPr whereas unreacted PPhCyPr shows the prevalent (S) configuration, indicating that the reaction occurred with asymmetric induction. These findings are rationalized by a mechanism based on the coordination to the metal of PPhCyPr mainly in the (R) configuration, followed by an intramolecular oxidation by the peroxide moiety.Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
