New indium-mediated cyclisation reactions of tethered haloenynes in aqueous solvent systems
作者:Andres Goeta、Matthew M. Salter、Hummad Shah
DOI:10.1016/j.tet.2006.01.094
日期:2006.4
The intramolecular cyclisation of tethered allyl bromides onto terminal alkynes mediated by metallic indium proceeds smoothly and cleanly in mixtures of THF and H2O to give unsaturated carbocycles and heterocycles in good yield. Alternatively, the cyclisation may be carried out in anhydrous THF with the aid of acid catalysis. The reaction is also mediated by a range of indium salts and proceeds with
Stereochemical Control in Intramolecular Ene Reactions of Crotyl Propargyl Ether Systems
作者:Koichi Mikami、Kazuhiko Takahashi、Takeshi Nakai
DOI:10.1246/cl.1987.2347
日期:1987.12.5
Stereochemical features are described of the title reactions leading to the γ-alkylidene-β-vinyloxolanes. Of particular interest is the high 1,2-trans diastereoselectivity observed for the (α-alkyl)crotyl and (α,β-dialkyl)crotyl ether systems with methoxycarbonyl group at the acetylenic terminus which remarkably facilitates the ene cyclization.
[Graphics]The cyclization of 1-bromo-2,7- and 1-bromo-2,8-enynes mediated by indium in DMF produced five- and six-membered cyclic compounds. Although KI was a necessary additive in the cyclization of terminal 1-bromo-2,7-enynes to give the desired products at 25degreesC, reactions of terminal 1-bromo-2,8-enynes and internal 1-bromo-2,7-enynes with indium proceeded at 100degreesC in DMF without KI. After cyclizations, subsequent cross-coupling reaction and iodolysis increase the usefulness of this reaction.
MIKAMI, KOICHI;TAKAHASHI, KAZUHIKO;NAKAI, TAKESHI, CHEM. LETT.,(1987) N 12, 2347-2350