Gold(III) chloride catalyzed cyclization of alpha-hydroxyallenes to 2,5-dihydrofurans.
[reaction: see text] Functionalized alpha-hydroxyallenes 1 were smoothly converted into the corresponding 2,5-dihydrofurans 2 by using 5-10 mol % of gold(III) chloride as catalyst. This mild and efficient cyclization method can be applied to alkyl- and alkenyl-substituted allenes at room temperature, furnishing tri- and tetrasubstituted dihydrofurans in good to excellent chemical yields and with complete axis to center chirality transfer.
Hoffmann-Röder
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A
Organic Chemistry II, Dortmund University, D-44221 Dortmund, Germany.
Krause
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N