I've ordered this one in the past - Premium Supplements - R-Alpha Lipoic Acid 300MG of Pure R-LIPOIC Acid 90 Count. - https://www.amazon.com/gp/product/B01M0QS5C7/. I think there are a lot that are OK but I would look at the ingredients to make sure they are 100% R-ALA or R-Lipoic Acid since some of them advertise as all natural but contain 50% S-ALA and 50% R-ALA. The S-ALA is the synthetic part and doesn't really help the body from what I've read.

-- (R)-Lipoic Acid: Unique ‘Mitochondrial Antioxidant’ Fights Premature Aging
https://nutritionreview.org/2019/07/r-lipoic-acid-unique-mitochondrial-antioxidant-fights-premature-aging/