The general procedure for the synthesis of 5,6-dimethoxyindole from the compound (CAS: 65907-71-3) is as follows (note: use the Biotage Initiator for microwave reactions in a 2-5 mL reaction vessel): in a microwave reactor vial, an appropriate amount of o-nitrostyrene or o-nitrocinnamate (0.3 mmol) was combined with phosphine (2.4 equiv) A suspension was formed by stirring in anhydrous solvent (5 mL) and oxygen was excluded by bubbling argon into the mixture. The vessel was sealed by adding MoO2Cl2(dmf)2 (5 mol%). The reaction mixture was heated to the indicated temperature under microwave radiation and maintained for the corresponding time. Post-reaction treatments vary depending on the phosphine used: when triphenylphosphine is used, the solvent is removed under vacuum and the product is purified by column chromatography (hexane-EtOAc); when polystyrene-loaded triphenylphosphine is used, the reaction mixture is filtered and the solvent is removed under vacuum to obtain a pure indole; when 2-(diphenylphosphino)benzoic acid is used, the reaction mixture is filtered and washed with alkali if necessary. Post-reaction treatments of other phosphines were carried out with reference to the methods described in the literature [14] [15].
