Single-step assembly of azabicyclo[3.3.0]octance systems via palladium-photoredox domino cycloaddition/transannular cascades

The azabicyclo[3.3.0]octane scaffold represents a privileged structural motif in medicinal chemistry, yet its synthesis typically requires laborious multi-step sequences. Herein, we disclose a palladium-photoredox relay catalytic strategy that combines dipolar [4 + 4] cycloaddition with transannular cascade processes. This domino protocol enables single-step construction of three distinct bioisosteric frameworks (aza-, oxaza-, and diazabicyclo[3.3.0]octanes) from linear precursors, achieving yields up to 94% with broad functional group tolerance. Gram-scale synthesis and diverse downstream transformations underscore the practical utility of this methodology.