We have studied the enantioselective transannular aminohalogenation reaction of unsaturated medium-sized cyclic benzosulfonamides by using both chiral Brønsted acid and phase-transfer catalysis. Under optimized conditions, a variety of bicyclic adducts can be obtained with good yields and high enantioselectivities. The mechanism of the reaction was also studied by using computational tools; we observed that the reaction involves the participation of a conformer of the nine-membered cyclic substrate with planar chirality in which the stereochemical outcome is controlled by the relative reactivity of the two pseudorotational enantiomers when interacting with the chiral catalyst.

Alice points out the preference of one conformational enantiomer by “crossing the mirror” thanks to the catalyst formed from the phosphoric acid and bromine “delivered” by N‐bromosuccinimide (NBS). Both the selected conformer and the new catalyst formed in situ merge their respective roads to converge on the product. More information can be found in the Research Article by U. Uria, P. Merino, J. L. Vicario, and co‐workers (DOI: 10.1002/chem.202202267).

A transannular approach has been developed for the construction of pyrrolo[1,2- b ]isoquinolinones starting from benzo-fused nine-membered enelactams. This process takes place in the presence of a halogenating agent and under Brønsted acid catalysis and proceeds via a transannular amidohalogenation, followed by elimination. The reaction has been found to be wide in scope, enabling the formation of a variety of tricyclic products in good overall yield, regardless of the substitution pattern in the initial lactam substrate. The reaction has also been applied to the total synthesis of a reported topoisomerase I inhibitor and to the formal synthesis of rosettacin. Further extension of this methodology allows the preparation of 10-iodopyrrolo[1,2- b ]isoquinolinones by using an excess of halogenating agent and these compounds can be further manipulated through standard Suzuki coupling chemistry into a variety of 10-aryl-substituted pyrrolo[1,2- b ]isoquinolinones.