Magnetic field dependence (red line in Figure ) Preparation of 3,5-dibromo-2-methylthiophene (B) according to the modified literature procedure 2 N-bromosuccinimide (9.05 g, 50.85 mmol, 2 eq) was dissolved in 60 ml of glacial acetic acid. Then the solution of 2-methylthiophene (2.46 ml, 25.42 mmol, 1 eq) in 25 ml of glacial acetic acid was added dropwise while stirring. The reaction mixture was stirred overnight at room temperature and then the content of the flask was poured into 400 ml of hexane and water mixture (1:1 by volume). The organic phase was separated and washed with 1 M NaOH and brine. The organic phase was dried over MgSO4 and evaporated using rotavap. The obtained yellow oil was purified by vacuum distillation (90-110°C, 10 mbar) yielding 4.94 g of a colorless oil (76%). H NMR (600 MHz, CDCl3, Figure ) δ 6.86 (s, 1H), 2.34 (s, 3H).