1: With potassium hydroxide in N,N-dimethyl-formamide T=20°C; 0.5 h; 2: With iodine in N,N-dimethyl-formamide T=0 - 20°C;

sodium hydroxide; hydroxylamine-o-sulphonic acid in ethanol; water T=55°C; 0.333333 h;

1 h; Heating;

1: 3,4-dihydro-2H-pyran; 4-chloro-1H-indazole With pyridinium p-toluenesulfonate in n-heptane; toluene T=40°C; 11 h; Inert atmosphereLarge scale; 2: 4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl-4',4',5',5'-tetramethyl-1,3,2-dioxaborolane With Ni(NO3)2·6H2O; triethylamine; triphenylphosphine in methanol T=0 - 25°C; 3.5 h; Inert atmosphereLarge scale;

pyridinium p-toluenesulfonate in dichloromethane T=45°C; 16 h;

pyridinium p-toluenesulfonate in dichloromethane T=45°C; 8 h; Inert atmosphere; Product distribution / selectivity;

1: 3,4-dihydro-2H-pyran; 4-chloro-1H-indazole With pyridinium p-toluenesulfonate in n-heptane; toluene T=40°C; 11 h; Inert atmosphereLarge scale; 2: 4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl-4',4',5',5'-tetramethyl-1,3,2-dioxaborolane With Ni(NO3)2·6H2O; triethylamine; triphenylphosphine in methanol T=0 - 25°C; 3.5 h; Inert atmosphereLarge scale;

1: pyridinium p-toluenesulfonate / dichloromethane / 16 h / 45 °C 2: potassium acetate / tri-cyclo-hexyl-phosphine; bis-triphenylphosphine-palladium(II) chloride / dimethyl sulfoxide / 16 h / 130 °C View Scheme