Die verwendung von diisobutylaluminiumhydrid zur stereoselektiven synthese von tertiären (e)-2-alkenylaminen, (e)-2-alken-4-inylaminen und 2(

In exploring versatile synthetic routes to (E)-allylamine derivatives with antimycotic properties, a new method has been found in the trans-reduction of tertiary 2-alkinylanunes by diisobutylaluminum hydride (DIBAH). The stereoselectivity of this reaction, which is in contrast to the well-known cis-hydroalumination of disubstituted alkynes, and the regioselectivity have been studied in detail. Tertiary 2-alkinylamines 1 were generally reduced to (E)-2-alkenylamines 2 in toluene at 40°, and tertiary 2,4-alkadiynylamines 3 yielded a mixture of(E)-2-alken-4-ynylamines 4 and 2(E),4(Z)-alkadienylamines 5 in high stereochemical purity. This reduction was clearly different with respect to reactivity and selectivity in comparison with other reactions also proceeding via trans-hydroalumination, namely the lithium aluminum hydride reduction of α-hydroxyacetylenes and the reaction of alkynes with LiAlH(iso-Bu)₂(n-Bu). Tertiary 6-hydroxy-2, 4-alkadiynylamines 10 were reduced to 6-hydroxy-2(E)-alken-4-ynylamines 11 with diisobutylaluminum hydride, whereas on treatment with lithium aluminum hydride 6-hydroxy-4(E)-alken-2-ynylamines 12 were obtained. LiAlH (iso-Bu)₂(n-Bu) did not react with 2-alkinylamine 1a and the 2,4-alkadiynylamine 3a was only monohydroaluminated without discrimination of the two acetylene groups. A possible mechanism for the diisobutylaluminum hydride reduction of 2-alkinylamines is presented.