Fig. 2: Evaluation of scope and application of the electrocatalytic asymmetric bromocyclization of tryptamine and tryptophol derivatives.

a Reaction scope regarding the tryptamine and tryptophol derivatives. 1 (0.3 mmol), (R)-CPA1 (5 mol %), PTC1 (10 mol %), NaHCO₃ (0.1 M in H₂O), NaBr (1 M in H₂O), toluene (6 mL), H₂O (5 mL), Pt anode and cathode (10 mm × 10 mm × 0.2 mm), stirring speed: 1000 r/min, 4 mA (2.5–3.0 F mol⁻¹), rt. Isolated yields were provided, and e.e. values were determined by chiral HPLC. Ts p-toluenesulfonyl, Cbz benzyloxycarbonyl, Alloc allyloxycarbonyl, Fmoc 9-fluorenylmethyl, Bn benzyl ⁺ Electric current at 3 mA for 18 h (6.7 F mol⁻¹). b A gram-scale protocol for the synthesis of 2c with reduced catalyst loading and high current and selected natural products that were synthesized from such bromination products.