Convert vfr mov file to cfr mov file Adobe Premiere has problems with variable frame rate. If I import a MOV file from an iPhone for example than audio and video is not synchron. I found out that the problem is the variable frame rate. Now I'm looking for a solution to fix this.

Currently I reencoded the videos in Windows Movie Maker for example but I don't want to have a loss in quality. I searched a bit and found out that AviSynth could do this for me. AviSynth cannot open MOV files so qtsource should be able to handle it. I placed it in the plugin folder of AviSynth but in the readme it says that the vfr feature is experimental and not working ...

Yes, I could use Handbrake but I always would have to reencode. Are there other options?
If you have Premiere, why not simply use Adobe Media Encoder?  I believe it should handle your needs.  There will always be some quality loss though as you will have to change codecs and the compression is going to differ.  You can use high quality formats to minimize the loss, but there is going to be loss.