Hydroamination reactions phenylacetylene with

A very interesting feature of the above system is that the reactions can be conducted under air, without solvent. Preparative scale (40 g) hydroamination of phenylacetylene with PhNHj yielded the acetophenone N-phenylimine in 92% isolated yield in 3 h (TOF = 100 h ). 

Metal complexes (Rh, Pd, and Zn) dissolved in an IL ([EMIM][rfj) and supported on diatomic earth exhibited higher activities and selectivities in the hydroamination of phenylacetylene with 4-isopropylaniline (Eq. (10.3)) [24] compared to the corresponding homogeneous reaction. 

The hydroamination of alkynes with primary and secondary ahphatic amines necessitates the use of higher amounts of catalyst (17%) and higher temperatures, and TOFs are low (<1 h ) [260]. With ahphatic and aromatic terminal alkynes and a 5-fold excess of primary aliphahc amines, the products are the corresponding imines (40-78% yield, TOF up to 0.3 h ). In contrast to the CujClj-catalyzed reaction of phenylacetylene and secondary ahphatic amines (Scheme 4-12), the HgClj-catalyzed reachon is fully regioselechve for the Markovnikov hydroamination products which do not evolve under the reachon condihons (Eq. 4.66) [260]. 

Synthesis of 1,2-disubstituted indole frameworks 257 via a formal 4 - - 1 cydoaddition between a 4-carbon unit and a primary amine was recently developed by Ackermann (Scheme 9.90) [242]. Reactive intermediates, 2-(o-haloaryl)enam-ines 256 were generated via the Cu(I)-catalyzed hydroamination of the orfHo-halo-substituted phenylacetylenes 254 with primary amines 255. A subsequent Cu(I)-catalyzed intramolecular enamine arylation reaction gave the corresponding indoles 257 in good yields. The authors demonstrated that alkynyl chlorides 254 could also participate in this cascade double amination process, albeit with a substantially diminished efHdency. 

Li has reported that cationic gold(III) complexes also catalyze the intermolecular hydroamination of terminal alkynes with aniline derivatives [17]. For example, reaction of a neat 1 1.5 mixture of phenylacetylene and aniline catalyzed by AUCI3 at room temperature followed by reduction with sodium borohydride led to isolation... 

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