1: thien-2-yl bromide With magnesium in diethyl ether T=20°C; 0.5 h; 2: 2,5-dibromo-3-(5,5-dimethyl-1,3-dioxan-2-yl)thiophene With [1,3-bis(diphenylphosphino) propane] dichloronickel(II) in diethyl ether Kumada coupling; 4 h; Heating;

toluene-4-sulfonic acid in toluene Heating;

1: 73 percent / aq. HBr; Br2 / 3 h / 50 °C 2: 98 percent / p-TsOH / benzene / 1 h / Heating View Scheme

1: thien-2-yl bromide With magnesium in diethyl ether T=20°C; 0.5 h; 2: 2,5-dibromo-3-(5,5-dimethyl-1,3-dioxan-2-yl)thiophene With [1,3-bis(diphenylphosphino) propane] dichloronickel(II) in diethyl ether Kumada coupling; 4 h; Heating;