It seems that for decades, Wendy Carlos has worked with producer and artistic partner Rachel Elkind. One of their first major successes was the album "Switched-On Bach" which took works by Bach and played them with sounds from the Moog synthesiser, Wendy being an acquaintance of Robert Moog the designer of this early synth. This wasn't another dull soulless exercise of mechanically playing notes with electronic sounds, but a demonstration that electronic instruments if used well could also play with humanity and feeling. Dr. Moog died in 2005 amid a flood of tributes for his pioneering electronic instruments - see our Electronic Music article for more information.
Carlos and Elkind were working on new material which they privately associated with Anthony Burgess' book "Clockwork Orange" when it was discovered that a film was being made of the novel. So they approached Stanley Kubrick with the material they had so far produced and got the job of scoring the new film. Incidentally, Anthony Burgess himself was a talented composer and created a number of works for the concert hall. Several of his books also have musical references, most notably "Napoleon Symphony" a fictionalised book about Napoleon in the structure of a symphony, recognising that Beethoven was originally going to dedicate his 3rd symphony to Napoleon, but the dedication was scored out on the manuscript when Napoleon's imperialist ambitions became obvious. Alex, the hero of "A Clockwork Orange" is a fan of Beethoven and listens to his music while fantasising about sex and violence. (Of course, this in itself leads to all sorts of philosophical questions about the interpretation of music.) So Carlos created synth versions of various extracts from Beethoven's 9th symphony (such as the Ode to Joy theme from the 4th movement), as well as works by other classical composers such as Purcell (his Funeral Music for Queen Mary) and Rossini. A particular effect for the extracts from the last movement Beethoven's 9th was to use a device called a "spectrum follower" which enabled an electronic recreation of some of the timbre of real voices. The result is something which is true to the music and the book, yet shows Alex's perverted view of the meaning of the music.
The collaboration with Stanley Kubrick was not totally devoid of problems and, though not as extreme as the case of Alex North and his work for 2001: A Space Odyssey, some material created for the movie was not able to be used. All the material both used and written for the film is available on the album "Clockwork Orange - Wendy Carlos's Complete Original Score". (Another album called "Stanley Kubrick's Clockwork Orange" contains the music actually used in the film.) The film "Tron" was an interesting move for Disney into the emerging realm of computer-generated effects. Initially the plan for the music was that Carlos would use acoustic instruments for the real world and moog synths for the virtual world within the computer. However this plan was later abandoned and the finished soundtrack tends to blend both soundscapes together.
Here are links for a range of recommended albums:
See Carlos's website at www.WendyCarlos.com. Among several others who have arranged classical music electronically, we can also recommend the albums of Isao Tomita.