Toward Acetylene Renaissance: Functionally Rich N-Aminoindoles from Acetylene Gas, Ketones, and Hydrazines in Two Steps.

A straightforward acetylene-based scalable strategy for the synthesis of highly functionalized N-aminoindoles has been discovered. This pot-, atom-, step-, and energy-economic strategy includes two simple stages: (i) a one-pot multimolecular (2 + 2) diastereoselective assembly of 6,8-dioxabicyclo[3.2.1]octanes (6,8-DOBCOs) from acetylene gas and ketones in the KOH/DMSO two-phase superbase catalytic system and (ii) a mild (rt, CF3COOH) cascade transformation of 6,8-DOBCOs under the action of hydrazines to afford N-(arylamino)-3-(acylpropyl)indoles in good yields.