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DOI: 10.1055/s-0033-1340032
Pd-Catalyzed Cross-Coupling Using Polymer-Supported Siloxane
Publikationsverlauf
Publikationsdatum:
18. Oktober 2013 (online)
Significance
Polymer-supported siloxane-transfer agent PSTA-I200 was prepared by the ring-opening metathesis polymerization of siloxane 1, which was synthesized from commercially available 5-norbornene-2-carboxaldehyde (eq.1). Palladium-catalyzed cross-coupling reactions of aryl- and alkenyllithium with organohalides were achieved by using stoichiometric amounts of PSTA-I200 (eq. 2, 9 examples, up to 98% yield).
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Comment
PSTA-I200 was characterized with IR, NMR, and GPC. After the cross-coupling reaction, PSTA-I200 was recovered via precipitation with MeCN. In the reaction of phenyllithium with 4-iodoanisole, PSTA-I200 was reused twice with a small decrease of reaction efficiency (1st reuse; 91% yield, 2nd reuse; 81% yield). An increase in the average molecular weight of the recovered PSTA-I200 was observed, probably due to polymer cross-linking by the attack of the oxyanion generated in situ on another siloxane of a different polymer chain.
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