1: N-(2,5-dibromo-1H-pyrrol-1-yl)-carbamic acid tert-butyl ester With isopropylmagnesium chloride lithium chloride complex in 1,4-dioxane T=0 - 20°C; 5 h; 2: N,N-dimethyl-formamide in 1,4-dioxane T=0 - 20°C;

1: N-(2,5-dibromo-1H-pyrrol-1-yl)-carbamic acid tert-butyl ester With isopropylmagnesium chloride lithium chloride complex in tetrahydrofuran T=9 - 23°C; 2 - 4 h; Inert atmosphere; 2: N,N-dimethyl-formamide in tetrahydrofuran; 1,4-dioxane T=2 - 23°C; 3 - 4 h; Inert atmosphere;

1.1: 1,3-dibromo-5,5-dimethyl-hydantoin / tetrahydrofuran; 1-methyl-pyrrolidin-2-one / 1 - 6 °C / Inert atmosphere; Darkness 2.1: isopropylmagnesium chloride lithium chloride complex / tetrahydrofuran; 1,4-dioxane / 9 - 23 °C / Inert atmosphere 2.2: 3 - 23 °C / Inert atmosphere View Scheme

1.1: hydrogenchloride / 1-methyl-pyrrolidin-2-one; water / 13 h / 90 °C / Inert atmosphere 2.1: 1,3-dibromo-5,5-dimethyl-hydantoin / tetrahydrofuran; 1-methyl-pyrrolidin-2-one / 1 - 6 °C / Inert atmosphere; Darkness 3.1: isopropylmagnesium chloride lithium chloride complex / tetrahydrofuran; 1,4-dioxane / 9 - 23 °C / Inert atmosphere 3.2: 3 - 23 °C / Inert atmosphere View Scheme

1.1: 1,3-dibromo-5,5-dimethyl-hydantoin / tetrahydrofuran; 1-methyl-pyrrolidin-2-one / 1 - 6 °C / Inert atmosphere; Darkness 2.1: isopropylmagnesium chloride lithium chloride complex / tetrahydrofuran / 2 - 4 h / 9 - 23 °C / Inert atmosphere 2.2: 3 - 4 h / 2 - 23 °C / Inert atmosphere View Scheme

1.1: hydrogenchloride / 1-methyl-pyrrolidin-2-one; water / 13 h / 90 °C / Inert atmosphere 2.1: 1,3-dibromo-5,5-dimethyl-hydantoin / tetrahydrofuran; 1-methyl-pyrrolidin-2-one / 1 - 6 °C / Inert atmosphere; Darkness 3.1: isopropylmagnesium chloride lithium chloride complex / tetrahydrofuran / 2 - 4 h / 9 - 23 °C / Inert atmosphere 3.2: 3 - 4 h / 2 - 23 °C / Inert atmosphere View Scheme