鈴木 教之

Five-membered metallacycloallene compounds, 2,5-disubstituted 1-zirconacylopenta-2,3-dienes were prepared from (E)-1,4-trialkylsilylbut-1-en-3-ynes in good yields. The structures of these compounds were determined by X-ray diffraction study. Contrary to our previous study on 2,4-disubstituted 1-zirconacylopenta-2,3-dienes, which gave alkynyl alcohols by the reaction with ketones after hydrolysis, the 2,5-bis(trialkylsilyl) complexes reacted with ketones to afford allenyl alcohols. Reactions with a nitrile gave a pyrolle compound probably via the formation of seven-membered 1-aza-2-zirconacylcohepta-3,4,7-triene compounds. When the (E)-1,4-bis(trialkylsilyl)but-1-en-3-ynes were treated with titanium isopropoxide/n-butyllithium followed by reaction with nitriles, the corresponding alkynyl ketones were obtained.

The cyclotrimerization of terminal alkynes, such as ethyl propynoate, arylacetylenes, and alkylacetylenes, catalyzed by phosphine-free [IrCl(cod)]2 is induced by a catalytic amount of tin(II) chloride in 1,4-dioxane to afford 1,2,4- and/or 1,3,5-trisubstituted benzenes. Terminal α,ω-diynes also undergo the cyclotrimerization with monoynes to form bicyclic benzene derivatives. cod=1,5-cyclooctadiene.

Reaction of η2-iminozirconocene chloride complexes with trimethylsilylethynyl lithium yields the corresponding five-membered aza-zirconacycloallenoids, which were also obtained from in situ generated zirconocene with alkynyl imines.