Abstract
AbstractA solid amino‐supported palladium catalyst is used in an oxidative domino reaction for the diastereoselective construction of alkyne‐substituted cyclopentenol compounds. This heterogeneous catalyst exhibits high efficiency and excellent chemoselectivity, as well as good recyclability. The chemoselectivity of the domino reactions was readily controlled by switching the solvent and catalyst. Asymmetric syntheses and an oxidative carbocyclization‐borylation reaction have also been developed based on the heterogeneous palladium catalyst.
Highlights
A solid amino-supported palladium catalyst is used in an oxidative domino reaction for the diastereoselective construction of alkyne-substituted cyclopentenol compounds
In our previous work the addition of catalytic amount of AgOTf dramatically improved the activity of this heterogeneous palladium catalyst in oxidative carbonylation of allene amides.[28]
Diamine completely shut down the reaction, probably due to the strong coordination of diamine to PdII, which inhibits the catalytic activity of the solid palladium catalyst. These results indicate that amine coordinates to PdII and affects its catalytic activity and selectivity,[32,33,34] and tertiary, secondary and primary amines are positive for improving the selectivity for 2 a by suppressing the b-H elimination or promoting the alkyne ligand exchange of Int-2.[35,36] 2) Under homogeneous reaction conditions, the starting material was always partially recovered and considerable amounts of Pd black was observed after the completion of the reaction (Figure 1 a and b, inset)
Summary
A solid amino-supported palladium catalyst is used in an oxidative domino reaction for the diastereoselective construction of alkyne-substituted cyclopentenol compounds. In our previous work the addition of catalytic amount of AgOTf dramatically improved the activity of this heterogeneous palladium catalyst in oxidative carbonylation of allene amides.[28] addition of AgOTf in the present reaction resulted in the sole production of 3 a (entry 10).[29] after screening other additives, we were delighted to find that addition of Et3N is favorable for switching the selectivity of the reaction towards 2 a.
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