1.1: sodium hydrogen sulfide hydrate / N,N-dimethyl-formamide / 5 h / 20 °C / |Inert atmosphere 1.2: pH Ca. 1 - 2 2.1: potassium phosphate; hydroxylamine-o-sulphonic acid / water; tetrahydrofuran / 0 - 20 °C View Scheme

1.1: sodium hydrogen sulfide hydrate / N,N-dimethyl-formamide / 5 h / 20 °C / |Inert atmosphere 1.2: pH Ca. 1 - 2 2.1: potassium phosphate; hydroxylamine-o-sulphonic acid / water; tetrahydrofuran / 0 - 20 °C 3.1: N,N-dimethyl acetamide / 18 h / 90 °C / |Inert atmosphere 4.1: dichloromethane / 4 h / 20 °C / |Inert atmosphere 5.1: tert.-butylnitrite; copper(ll) bromide / acetonitrile / 0.17 h / 67 °C / |Inert atmosphere View Scheme