Mechanism of palladium-catalyzed diene cyclization/hydrosilylation: direct observation of intramolecular carbometalation.
The results of kinetic, deuterium-labeling, and low-temperature NMR studies have established a mechanism for the palladium-catalyzed cyclization/hydrosilylation of dimethyl diallylmalonate (1) with triethylsilane involving rapid, irreversible conversion of the palladium silyl complex [(phen)Pd(SiEt(3))(NCAr)](+) [BAr(4)](-) [Ar = 3,5-C(6)H(3)(CF(3))(2)] (4b) and 1 to the palladium 5-hexenyl chelate complex [(phen)Pd[eta(1),eta(2)-CH(CH(2)SiEt(3))CH(2)C(CO(2)Me)(2)CH(2)CH=CH(2)]](+) [BAr(4)](-) (5), followed by intramolecular carbometalation of 5 to form the palladium cyclopentylmethyl complex trans-[(phen)Pd[CH2CHCH2C(CO2Me)2CH2CHCH2SiEt3](NCAr)]+ [BAr4]- (6), and associative silylation of 6 to release 3 and regenerate 4b.
Perch
Nicholas S
NS
P. M. Gross Chemical Laboratory, Duke University, Durham, North Carolina 27708-0346, USA.
Widenhoefer
Ross A
RA
D000475:Alkenes / Q000138:chemical synthesis*; D002384:Catalysis; D002614:Chelating Agents / Q000737:chemistry; D003500:Cyclization; D007202:Indicators and Reagents; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008670:Metals / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*; D012821:Silanes / Q000138:chemical synthesis / Q000737:chemistry
D000475:Alkenes; D002614:Chelating Agents; D007202:Indicators and Reagents; D008670:Metals; D012821:Silanes; D010165:Palladium