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Ring closure reactionsO 0130 DOI: 10.1002/chin.201049027

Gold-Catalyzed Room-Temperature Cycloisomerization of Alkynes and Unacti-vated Enolizable Ketones. — This new method for cycloisomerization of unactivated ketones with alkynes proceeds under gold catalysis at room temperature. The ring size of starting material plays an important role in the cyclization. Five, six, and seven--membered rings (I) afford the desired conjugated alkenes (II) as sole products but, for 8-membered ring (VIII) formation of exomethylene product (IX) is observed albeit in low yield. In contrast, cycloisomerization of acyclic compound (X) gives a mixture of three regioisomers. Substrate (VI) bearing two enolizable carbonyl groups gives bi-cyclic product (VII) as a mixture of two diastereomers. Under similar conditions sub-strate (XVI) without an enolisable α-position leads to bicyclic enone (XVII) in moder-ate yield. — (DAVIES*, P. W.; DETTY-MAMBO, C.; Org. Biomol. Chem. 8 (2010) 13, 2918-2922, DOI:10.1039/c003473h ; Sch. Chem., Univ. Birmingham, Edgbaston, Birmingham B15 2TT, UK; Eng.) — S. Adam

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ChemInform 2010, 41, issue 49 © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

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ChemInform 2010, 41, issue 49 © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim