1: With potassium hydroxide in 1-methyl-pyrrolidin-2-one; water T=100°C; 1 h; Inert atmosphere; 2: With copper(I) oxide; 1,10-phenanthroline; propionic acid in 1-methyl-pyrrolidin-2-one T=70 - 170°C; 16.1667 h; Inert atmosphere;