After the first composition lessons with Ingo Schmitt from 1962 to 1965 he studied until 1970 composition at the Musikhochschule Cologne with Rudolf Petzold and piano with Günter Ludwig. In 1968 he was a scholarship holder of the Studienstiftung des Deutschen Volkes, from 1971 lecturer in theory at the Musikhochschule Hamburg. In 1974 he was awarded the Promotion Prize of the State of North Rhine-Westphalia for Music, followed by a one-year stay in the Villa Massimo in 1978/79. From 1981 he was Professor of Composition and Theory at the Musikhochschule Hamburg. He spent the years 1984 and 1985 in Paris with a scholarship for the Cité Internationale des Arts Paris. From 1986 he was a member of the Free Academy of the Arts Hamburg. In 1987, the city of Wuppertal awarded him the Von der Heydt Prize. In 1994, he moved from Hamburg to the professorship of composition at the Musikhochschule Mannheim, from 1997 he was a member of the Free Academy of the Arts Mannheim. In 2001/02 he again received a scholarship for the Cité Internationale des Arts, Paris. From 2005 he worked as a freelance composer.
For the composer born in the first postwar year, as with many of his contemporaries, the confrontation with the music of the Second Viennese School “was at the beginning of the appropriation of musical modernity, which had been ostracized in National Socialist Germany. But his studies at the Viennese school were [...] easier than at Boulez, Nono or Stockhausen. Its derivation of the serial method challenged Leyendecker. “(Lutz Lesle) In particular, the music of Alban Berg, in which Leyendecker saw a” residual tonality “preserved, became influential for the composer. At the beginning of his artistic career, Leyendecker “often took one step behind the a priori fixed and secured basic form in the genesis of his musical material.” (Lutz Lesle) Later, more and more fixed motivic figures became important, yet still a metamorphosis of the musical Allow material. An important concern of Leyendecker remained to write a comprehensible, emotionally comprehensible music without having to congratulate the audience. From the 2000s, Leyendecker's compositions find a turn towards clear structures and form concepts. This manifests itself in his orchestral works as well as in chamber music. “Whereas Leyendecker's early chamber music compositions were more like microscopic tonal structures from which his sonic cosmos could unfold in fascinating architectonics, the bass clarinet quintet is more likely to show a great, downright mischievous gesture. Of course, this never arises out of a musical end in itself, but always finds its decisive impulse in the compelling richness of Leyendecker's world of ideas. “(Timo Jouko Herrmann) In some compositions from Leyendecker's late work, there is also the pleasurable engagement with the music of other epochs, such as in the Pensées sur un prélude for orchestra, which takes Claude Debussy's piano piece Des pas sur la neige as a compositional starting point, or in the orchestral piece Evocazione, which evokes the Comtur scene from Wolfgang Amadeus Mozart's Don Giovanni impressively. The double orchestra technique of the Mannheim School proves to be a tribute to Leyendecker in his Mannheim concert for two chamber orchestras. Leyendecker died of heart failure at the age of 72 years. (Wikipedia)