Hydroxy-bearing cyclopropenes react with allylindium reagents to undergo clean allylindation both in organic and aqueous media, in which the chelation of the hydroxyl group to indium plays the central role. The regio- and stereoselectivity have been regulated both by the location of the hydroxyl group in the molecules and the reaction solvents. In particular, the allylindation in water shows marked differences from that in organic solvents; the regio- and stereoselectivity have totally been reversed compared with those in organic solvents. Unusually stable cyclopropyl-indium compounds have been isolated from the reaction of 1-(omega-hydroxyalkyl)cyclopropenes and the structure has fully been established by X-ray crystallography.
The successive double allylation of cyclopropenes with allylindium sesquiiodide and allyl iodide proceeded with a cis-addition mode in the presence of other organometallics (e.g. Grignard reagent, cuprate, Et(2)Zn and Et(3)Al), giving the corresponding cis-diallylcyclopropanes in high yields.
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Cyclopropane derivatives Q 0021Cis Double Allylation of Cyclopropenes Using Cyclopropylindium Reagents. -The double allylation of cyclopropenes (I) proceeds in a stepwise manner. Allylation with allylindium sesquiiodide, genearated in situ, is followed by metalation and a second allylation with allyl iodide. The reaction proceeds with excellent cis-selectivity for the diallyl unit, while the configuration relative to the third stereocenter is strongly influenced by the C-3 substituent structure. No reaction takes place in the presence of strongly chelating hydroxyalkyl substituents. -(HIRASHITA*, T.; SHIRAKI, F.; ONISHI, K.; OGURA, M.; ARAKI, S.; Org.
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