Synthesis of semicyclic/exocyclic amino-1,3-dienes by organocuprate addition to semicyclic propyniminium salts

Article abstract of DOI:10.1002/prac.19963380186

Conjugate addition of organocuprates to the 2-ethynyl-substituted cyclic iminium triflates 3 generates aminoallenes which tautomerize immediately to semicyclic 2-amino-1,3-dienes (6, 8) or exocyclic 1-amino-1,3-dienes (9, 10) with the enamine function incorporated into or attached to a 5-, 6-, or 7-membered ring. In those cases where tautomeric equilibria between the two aminodiene species are possible, the five-membered ring exists virtually exclusively with an exocyclic enamine double bond, but the six-membered ring prefers the exocyclic form. The seven-membered ring can accomodate both forms quite well. Johann Ambrosius Barth 1996.