The dearomative ispo-cyclization of alkynyl-arenes has become a popular area of investigation for the synthesis of spirocyclic molecules. The majority of these methods have focus on electrophilic activation of the alkyne, either through stoichiometric halogenating reagents or Lewis-acidic transition metal catalysts. Additionally, activation of the alkyne via radical processes has been heavily explored. Here, we present an approach which relies on activation of the arene component in an effort to increase it's latent nucleophilicity towards a pendant alkynamide side-chain. Under these condtions, p-hydroxyl N-aryl alkynamides are activated via base-catalysis to undergo a 5-endo-dig cyclization, thereby forging a new five-membered ring, while simultaneously dearomatizing the parent arene. This approach is a mechanistic compliment to the earlier work in this field since it focuses on arene/nucloephile activation rather than alkyne/electrophile activation. As a result, the substrate scope of these two distict approaches is divergent, and a wider array of spriolactams is made available.

Organic-base-catalyzed dearomative ipso-cyclization of N-aryl-alkynamides for the synthesis of spirocyclic amides

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