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An efficient gold-catalyzed cyclization of 2-alkynylaldehyde cyclic acetals has been developed for the synthesis of indenone derivatives. A wide variety of functionalized indenone derivatives can be obtained in good-to-excellent yields. HMBC and NOESY NMR analyses and mechanistic elucidation experiments revealed that the cyclization occurs via a 1,5-H shift. The cyclic acetal group promoted the 1,5-H shift by activating the benzylic C-H bond and preventing the migration of the alkoxy group by tethering both alkoxy groups.

The reaction of oxime esters with cyanotrimethylsilane (Me(3)SiCN) under the influence of a catalytic amount of lanthanide compounds produced alpha-trimethylsilyloxydinitrile derivatives in excellent yields accompanied with the formation of trimethylsilyl oxime ethers. Among the lanthanoid catalysts examined, La(O(i)()Pr)(3) was found to be the best catalyst. The reaction seems to proceed through the formation of acyl cyanides as intermediates, followed by the addition of Me(3)SiCN to them. Additionally, the reaction of acetic anhydride with Me(3)SiCN catalyzed by La(O(i)()Pr)(3) gave 1-trimethylsilyloxyethane dinitrile. Thus, various alpha-trimethylsilyloxydinitriles were synthesized in good yields by allowing oxime esters or acid anhydrides to react with Me(3)SiCN in the presence of a catalytic amount of La(O(i)()Pr)(3).