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  • Title: W(CO)5(L)-catalyzed endo-selective cyclization of allenyl silyl enol ethers: an efficient method for the cyclopentene annulation onto alpha,beta-unsaturated ketones.
    Author: Miura T, Kiyota K, Kusama H, Lee K, Kim H, Kim S, Lee PH, Iwasawa N.
    Journal: Org Lett; 2003 May 15; 5(10):1725-8. PubMed ID: 12735762.
    Abstract:
    [reaction: see text] Indium-mediated allenylation of alpha,beta-unsaturated ketones in the presence of tert-butyldimethylsilyl triflate and dimethyl sulfide gives 6-siloxy-1,2,5-trienes, which undergo W(CO)(5)(L)-catalyzed 5-endo cyclization to give the corresponding cyclopentene derivatives in good yield. Furthermore, this novel W(CO)(5)(L)-catalyzed cyclization of allenyl silyl enol ethers proceeds in a 6-endo manner when 5-siloxy-1,2,5-trienes are employed as a substrate. In these reactions, effective electrophilic activation of allenyl compounds for attack by silyl enol ethers is achieved using a catalytic amount of W(CO)(6).
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