Ind 2 TiMe 2 ‐Catalyzed Addition of Methyl‐ and Ethylamine to Alkynes

We describe a very simple hydrogenation‐like experimental protocol for the addition of gaseous methyl‐ and ethylamine to alkynes in the presence of Ind 2 TiMe 2 as the catalyst. For efficient hydroamination reactions it is sufficient to stir a mixture of the alkyne and the catalyst in toluene at temperatures between 80 °C (terminal alkynes) and 105 °C (internal alkynes) under a constant pressure of 1 atm of the corresponding amine. After subsequent reduction of the initially formed imines, methyl‐ and ethylamine derivatives are the final products of the described one‐pot reaction sequences. In the case of 2‐alkyl‐1‐phenylalkynes as starting materials, biologically interesting 2‐phenylethylamine derivatives possessing a small methyl or ethyl substituent at the N atom are easily accessible by the new reaction protocol. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)