1: P2S5 2: (i) aq. NaOH, (ii) (thermolysis) View Scheme

sodium hydroxide in methanol; water T=80°C; 3 h; Inert atmosphere;

1.1: sodium hydride / tetrahydrofuran; mineral oil / 0.5 h / 0 °C / Inert atmosphere 1.2: 6 h / 20 °C / Inert atmosphere 2.1: sodium hydroxide / methanol; water / 3 h / 80 °C / Inert atmosphere 2.2: Inert atmosphere 3.1: palladium diacetate; potassium carbonate; triphenylphosphine / 1-methyl-pyrrolidin-2-one / 24 h / 120 °C / Inert atmosphere View Scheme

copper(l) iodide; caesium carbonate; (2S,4R)-2-carboxy-4-hydroxypyrrolidine in N,N-dimethyl-formamide T=90°C; 24 h; Inert atmosphere;