Many spirits of alchemy teach this in Franz Bardons Evocation book, such as Kirek, Siges, Mummiah.
Not only do they teach that but physical immortality as long as you wish as well.
Also in Justin Bedwells book called Secrets of Magic Revealed he has a section on alchemy that uses the golden flower meditation from taosim that can lead to astral immortality and possibly physical as well as other meditations given to him by spirits of alchemy.
Justin went through Bardons system and presents his own magical foundational training in that book.
He also states that working with angels, elementals and the elements can give it to you just because of your vibrational change making you immune to the dissolution of the elements on your astral body.
You become more like what you hang around with due to the law of resonance.
Also kundalini once awakened properly creates what he calls a golden body of light that is capable of astral immortality if you want.
He has chakra work and kundalini work in the advanced adept section in the back of his book.
He had a blog where he gave out a sigil he made of the philosophers stone that is supposed to give astral immortality as well as other powers over time as you build it into your energy body.
I posted it in another thread concerning immortality a while ago…ill see if I can find the link to that thread and put it here.
Robert Bruce talks about Kundalini and its possibilities of immortality as well.
And if you want a daemon from goetia, Zagan is a vampiric spirit said to teach immortality as well.