Various alkynes reacted with allyl tosylates in the presence of palladium catalysts, giving polysubstituted benzenes with good to high regioselectivity. Pentasubstituted and trisubstituted benzenes were readily prepared by reaction of internal alkynes and terminal alkynes, respectively. The combination of allyl alcohols and p-toluenesulfonic anhydride could be utilized in place of isolated allyl tosylates. The cyclization of diynes with allyl tosylate afforded bicyclic compounds containing an aromatic ring.
Reaction of zirconacyclopentadienes with electrophiles such as benzaldehyde, methyl methacrylate and 1-bromo-2-butyne after treatment with RLi
Zirconacyclopentadienes reacted with electrophiles after treatment with alkyllithium. For example, the reaction with benzaldehyde after treatment with methyllithium to give a nucleophilic addition product of a dienyl moiety to aldehyde, dienylcarbinol, in a moderate yield. Similar reaction of a zirconacyclopentadiene using butyllithium with methyl methacrylate afforded a Michael addition product in a good yield. Treatment of zirconacyclopentadienes with n-BuLi followed by 1-bromo-2-butyne gave a mono-propargylated diene derivative in 95% yield after hydrolysis. When propargyl chloride was treated with n-BuLi first and then added to zirconacyclopentadienes, penta-substituted benzene derivatives were formed in high yields. (C) 2004 Published by Elsevier Ltd.
Carbon−Carbon Bond Formation Reaction of Zirconacyclopentadienes with Alkynes in the Presence of Ni(II)-complexes
tetrahydroisoquinoline derivatives in good to high yields. This procedure was also used for the selective preparation of benzene derivativesfrom three different alkynes. The use of trimethylsilyl-substituted alkyne as the first, second or third alkyne afforded desilylated benzene derivatives. The reaction of zirconacyclopentadienes with allenes gave benzene derivatives as a mixture of two isomers.