1.1: 1,3-dibromo-5,5-dimethyl-hydantoin / 1,2-dichloro-ethane / 7.5 h / 80 - 90 °C / Industry scale 2.1: potassium methanolate / toluene / -5 - 10 °C / Inert atmosphere; Industry scale 3.1: sodium hydroxide / isopropyl alcohol; methanol / 20 - 60 °C / Industry scale 3.2: 30 - 35 °C / Industry scale 4.1: urea / xylene / 6 h / Reflux 5.1: borane-THF / tetrahydrofuran / 1.25 h / 0 °C / Inert atmosphere; Steam bath 5.2: Cooling with ice View Scheme