Thank you very much Sven. With these hints, I managed to sync the iPhone win a win vm. The puzzle which was missing for me was that I had to detach the usb controller from the sys-usb. After this I could successfully attach it to the win vm. Followed by installing the drivers you suggested, the iPhone was found and could be used.
Have you managed to enable Wi-Fi sync? My assumption was that I only have to sync once using USB and could sync over wifi afterwards. Unfortunately, even after enabling it in iTunes, the iPhone seems not to be found although both devices are connected to the same wifi.
Thanks a lot again!