Fig. 5: Mechanistic studies.
From: Chiral Brønsted acid-controlled intermolecular asymmetric [2 + 2] photocycloadditions
a Ultraviolet-visible spectra of 1 and AC-3 in CH2Cl2. b X-ray crystal structure of acid-bound substrate. c Binding depiction of acid-bound substrate. d HOMO(π) and LUMO(π*) of 1 and 1–H+–AC-4.
