The effects of the main reaction parameters on yield and regioselectivity in the hydrocarboalkoxylation of Et 3-butenoate, catalyzed by a [Cl2Pd(PPh3)2]-PPh3 system, are examd. A higher regioselectivity towards di-Et glutarate is obtained in a polar solvent, such as EtOH, or in the presence of higher concns. of added PPh3 or under low CO pressure. As a general trend, higher regioselectivity is obtained at the expense of the yield. In EtOH, high yields but low regioselectivities are obtained when the catalyst is employed together with HCl; HCl strongly inhibits the catalysis in C6H6. In the presence of H2 no hydroformylation occurs, the yield is much higher, and the regioselectivity remains practically the same; moreover, the inhibitory effect of HCl is suppressed. The Pd catalyst is highly active and regioselective in the presence of SnCl2.
Metals in organic syntheses. Part XII. Hydrocarboalkoxylation of ethyl 3-butenoate catalyzed by palladiumcomplexes
TONIOLO, Luigi;
1985-01-01
Abstract
The effects of the main reaction parameters on yield and regioselectivity in the hydrocarboalkoxylation of Et 3-butenoate, catalyzed by a [Cl2Pd(PPh3)2]-PPh3 system, are examd. A higher regioselectivity towards di-Et glutarate is obtained in a polar solvent, such as EtOH, or in the presence of higher concns. of added PPh3 or under low CO pressure. As a general trend, higher regioselectivity is obtained at the expense of the yield. In EtOH, high yields but low regioselectivities are obtained when the catalyst is employed together with HCl; HCl strongly inhibits the catalysis in C6H6. In the presence of H2 no hydroformylation occurs, the yield is much higher, and the regioselectivity remains practically the same; moreover, the inhibitory effect of HCl is suppressed. The Pd catalyst is highly active and regioselective in the presence of SnCl2.
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