Diastereoselective Synthesis of Dearomatic 2‐oxa‐7‐azaspiro[4.5]decane Derivatives through Gold and Palladium Relay Catalytic Tandem Cyclization of Enynamides with Vinyl Benzoxazinanones

Abstract We present a diastereoselective Au/Pd relay catalytic tandem cyclization reaction to produce dearomatic 2‐oxa‐7‐azaspiro[4.5]decane derivatives under mild conditions. This process involves generating furan‐derived azadiene from readily available enynamide, followed by a [2+4] cycloaddition with Pd‐ π ‐allyl dipole decarboxylated from vinyl benzoxazinanone. Our method efficiently constructs the spiro[4.5]decane skeleton, achieving yields ranging from 31–97% and diastereoselectivities from 6:1 dr to >20:1 dr across 34 examples. This research introduces new cycloaddition sites for azadienes as 1,2‐dipoles and offers a reliable approach for constructing oxa‐azaspiro[4.5]decane frameworks.