Titanium-Catalyzed [6π+2π]-Cycloaddition of Alkynes and Allenes to 7-Substituted 1,3,5-Cycloheptatrienes

The reaction of 7-alkyl(allyl, phenyl)-1,3,5-cycloheptatrienes with alkynes and allenes, catalyzed by the two-component Ti(acac)(2)Cl-2-Et2AlCl system, resulting in the formation of substituted bicyclo[4.2.1]nona-2,4-dienes and bicyclo[4.2.1]-nona-2,4,7-trienes in up to 90% yield, was accomplished. The structures of the obtained compounds were confirmed by X-ray diffraction and by H-1 and C-13 NMR spectroscopic analysis.