Typical procedure: A mixture of ethyl L-(-)-lactate (100 mg, 0.85 mmol), 3,5-dinitrobenzoic acid (198 mg, 0.935 mmol), triphenylphosphine (446 mg, 1.7 mmol), ethyl 2-(3,4-dichlorophenyl)hydrazinecarboxylate (21.2 mg, 0.085 mmol), iron(II) phthalocyanine (48.3 mg, 0.085 mmol) and activated MS5Å (400 mg) in THF (1.7 mL) is heated at 65 °C for 24 h under air (balloon). After the reaction mixture is cooled to room temperature and filtered, the solvent is removed under reduced pressure. The residue is purified by silica gel chromatography (eluent: n-hexane/EtOAc = 6:1). Ethyl 2-(3,4-dichlorophenyl)azocarboxylate (20.1 mg, 0.0813 mmol, 96%) is recovered from the first fraction as a red solid. The second fraction gives (R)-1-ethoxycarbonylethyl 4-nitrobenzoate (209 mg, 0.668 mmol, 79%, 98:2 e.r.) as a white solid.

Typical Procedure: Hydrazine hydrate (2 eq.) is added to a mixture of nitro compound (0.67 mmol) and catalyst (0.5 mol%) in water/ethanol (1:1) or ethylene glycol (10 mL). The reaction solution is refluxed to reflux at 120°C and the progress of the reaction is monitored by TLC (silica gel; hexane―ethyl acetate) and GC-MS. Upon completion, the reaction mixture is cooled to ambient temperature and extracted with ethyl acetate (3 × 5 mL). The combined organic fractions are (washed with water in cases where ethylene glycol is used as solvent) dried under reduced pressure. The product mixture is subjected to column chromatography (silica 230-400; hexane―ethyl acetate).