Polymer-supported palladacycles: efficient reagents for synthesis of benzopyrans with palladium recovery. Relationship among resin loading, Pd:P ratio, and reactivity of immobilized palladacycles.
[reaction: see text] Oxapalladacycles were immobilized on polystyrene-divinylbenzene supports and treated with 3-aryl-2-propynoates or 1-alkyl-1,2-propadienes to afford 2H-1-benzopyrans in yields superior to those for solution-phase experiments. Isolation of benzopyrans was facilitated, and 71-80% of the palladium was recovered. Effects of resin loading with phosphorus and palladium were studied, and the optimum immobilized palladacycles featuring a medium loading with P (1.35 mmol P/g) and a high loading with Pd (Pd:P ratio 1:1.7) were identified. Resins with higher swelling capacities were more reactive.
Hershberger
John C
JC
Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045-7582, USA.
Zhang
Lei
L
Lu
Genliang
G
Malinakova
Helena C
HC
D001578:Benzopyrans / Q000737:chemistry*; D003500:Cyclization; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*
D001578:Benzopyrans; D010165:Palladium