Older auto-save backups for Word documents (.asd) may be most likely only recovered (back to .doc) using specific older versions of Word, up to version 2007 to be precise. Once that is done, you can resave the document to RTF format. Other than that, it will be probably impossible to recover the document from .asd by other means.
Unfortunately, no 3rd party software that can recover .asd files exists, so using the recovery function in Word remains the only option to achieve asd to rtf conversion.