A new access to spiro[5.5]undecane frameworks was reported through the ZnMe₂-promoted alkynylation of salicylaldehyde and HCO₂H-mediated dearomatizative cyclization which can be used to construct an all-carbon quaternary spirocenter. This method can be applied to the rapid synthesis towards a series of useful motifs of natural products, such as the core of elatol and aphidicolin.