A process for preparing DELTA · 1 · -Pyrrolinen

2,5-bisaryl-DELTA · 1 · -Pyrrolinen of formula (I) in which F1 DOLLAR DOLLAR A Ar and Ar · 1 · · · 2 have the meanings given in the description, DOLLAR A can be prepared by DOLLAR A converting azides of formula (II) DOLLAR F2 with a trialkylphosphine or a trialkylphosphite or Triarylphoshin or a reducing agent in the presence of a diluent and if appropriate in the presence of a catalyst.