Question: What is the name of this French composer, conductor, writer, and organiser of institutions, who collaborated with Gunter Reich to interpret the works of Arnold Schoenberg?

Context paragraphs:
Die Jakobsleiter: Die Jakobsleiter ("Jacob's Ladder") is an oratorio by Arnold Schoenberg that marks his transition from a contextual or free atonality to the twelve-tone technique anticipated in the oratorio's use of hexachords. Though ultimately unfinished by Schoenberg the piece was prepared for performance by Schoenberg student Winfried Zillig at the request of Gertrude Schoenberg.

Style and Idea (Schoenberg): Style and Idea: Selected Writings of Arnold Schoenberg (in German: "Stil und Gedanke") is the name for a published collection of essays, articles and sketches by Arnold Schoenberg, that has appeared in various forms.

Günter Reich: Günter Reich (22 November 1921 – 15 January 1989), also spelled Günther Reich and Gunther Reich, was an Israeli baritone of German birth.  He was a member of the Staatsoper Stuttgart for more than 20 years and is known for interpreting the works of Arnold Schoenberg in collaboration with Michael Gielen and Pierre Boulez.

Pierre Boulez: Pierre Louis Joseph Boulez CBE (] ; 26 March 1925 – 5 January 2016) was a French composer, conductor, writer and organiser of institutions.  He was one of the dominant figures of the post-war classical music world.

Herzgewächse: Herzgewächse (German: "Foliage of the Heart"), Op. 20, is a composition by Austrian composer Arnold Schoenberg scored for coloratura soprano, celesta, harmonium, and harp.  The text is taken from a poem of the same name by Maurice Maeterlinck.  The duration of the work is approximately three-and-a-half minutes, making it the shortest of Schoenberg's works with an opus number.  The work is also notable for the extreme demands made on the singer which at one point has to ascend to a high F ("pianissimo"), nearly two-and-a-half octaves above middle C.

Anton Webern: Anton Friedrich Wilhelm (von) Webern (] ; 3 December 188315 September 1945) was an Austrian composer and conductor.  Along with his mentor Arnold Schoenberg and his colleague Alban Berg, Webern was at the core among those within and more peripheral to the circle of the Second Viennese School, including Ernst Krenek and Theodor W. Adorno.  As an exponent of atonality and twelve-tone technique, Webern exerted influence on contemporaries Luigi Dallapiccola, Křenek, and even Schoenberg himself.  As a tutor, Webern guided and variously influenced Arnold Elston, Frederick Dorian (Friederich Deutsch), Matty Niël, Fré Focke, Karl Amadeus Hartmann, Philipp Herschkowitz, René Leibowitz, Humphrey Searle, Leopold Spinner, and Stefan Wolpe.

Moses und Aron: Moses und Aron (English: "Moses and Aaron") is a three-act opera by Arnold Schoenberg with the third act unfinished.  The German libretto is by the composer after the Book of Exodus.  Hungarian composer Zoltán Kocsis completed the last act, with Schoenberg's heirs' permission, in 2010, but as of 2014 "Moses und Aron" was almost always performed as Schoenberg left it in 1932, with only two of the planned three acts completed.

Leonard Stein: Leonard David Stein (December 1, 1916 – June 23 or 25, 2004) was a musicologist, pianist, conductor, university teacher, and influential in promoting contemporary music on the American West Coast.  He was for years Arnold Schoenberg's assistant, music director of the Schoenberg Institute at USC, and among the foremost authorities on Schoenberg's music.  He was also an influential teacher in the lives of many younger composers, such as the influential minimalist La Monte Young.

Second Viennese School: The Second Viennese School (German: Zweite Wiener Schule, Neue Wiener Schule ) is the group of composers that comprised Arnold Schoenberg and his pupils and close associates in early 20th century Vienna, where he lived and taught, sporadically, between 1903 and 1925.  Their music was initially characterized by late-Romantic expanded tonality and later, following Schoenberg's own evolution, a totally chromatic expressionism without firm tonal centre, often referred to as atonality; and later still, Schoenberg's serial twelve-tone technique.  Though this common development took place, it neither followed a common time-line nor a cooperative path.  Likewise, it was not a direct result of Schoenberg's teaching—which, as his various published textbooks demonstrate, was highly traditional and conservative.  Schoenberg's textbooks also reveal that the Second Viennese School spawned not from the development of his serial method, but rather from the influence of his creative example.

Arnold Schoenberg Choir: The Arnold Schoenberg Choir (German: "Arnold Schoenberg Chor" ) is a Viennese/Austrian choir which was founded 1972 by Erwin Ortner, who is still its artistic director.  The choir has a high reputation both among conductors and among critics and the musical scene in general.  All members of the choir have broad experience and expertise in vocal music; most of them have graduated from or are currently studying at the Vienna University of Music and Performing Arts.  The choir is named after Viennese composer Arnold Schoenberg.

Supporting paragraphs: Günter Reich Pierre Boulez
Answer: Pierre Boulez