Conformationally Driven Two- and Three-Photon Cascade Processes in the Stereoselective Photorearrangement of Pyrroles

A TBSO group has been shown to exert a high degree of stereocontrol during the two-photon photocycloaddition/rearrangement of N-butenylpyrroles to complex tricyclic aziridines. Moreover, this and other bulky groups have been shown to change the outcome of the reaction, promoting a new two-photon sequence to tricyclic imines and an unprecedented stereoselective three-photon sequence to azabicyclo[3.3.1]nonanes