The palladium-catalyzed arylative dearomatization of phenols to yield spirocyclohexadienone products in good to excellent yields has been developed. Preliminary results demonstrate that the formation of the spirocyclic all-carbon quaternary center can be accomplished with high levels of enantiocontrol (up to 91% ee).

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The chemistry of alkyne cyclooligomers dates back to the 18th century with the work of Berthelot1 and Kekulé;2 however, the first dimeric species, namely the cyclobutadienes, were only reported in 1959 as an ?/4-complex3a b and in 1968 as a free, not complexed molecule with a push-pull substitution pattern.30•4 Much more recently, the chemistry of the related A3-phosphaalkyne (A) cyclooligomers has attracted considerable attention.5 A few dimers are stable in the coordination sphere of transition metals,5•6 but free lA3,3A3-diphosphetes B and 1A3,2A3diphosphetes C behave as their antiaromatic carbon analogs and prove to be elusive.5•7 In the same vein, only one example of transition metal-coordinated A3-phosphete D,8 arising from the inner sphere codimerization of alkynes with A3-phosphaalkynes A, is known. In marked contrast, although a very few A5-phosphaalkynes E are stable,9 most of them spontaneously dimerize, leading to stable lA5,3A5-diphosphetes F.10 Here we report the first example of codimerization of a A3-phosphaalkyne A with a A5-phosphaalkyne E (Chart 1).In contrast to most diazo derivatives,5b 0 bis[diisopropylamino)phosphino](trimethylsilyl)diazomethane (1) does not undergo

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