-used (along with 4-Hydroxycoumarin) in the synthesis of Warfarin (Coumadin)
-4-Hydroxycoumarin + Indan-1,3-dione -> Warfarin (Coumadin)
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References:
Goodman & Gilman's: The Pharmacologic Basis Of Therapeutics - 10th Edition - 2001. Chapter 55.