Acetic Anhydride → 6,8-dimethoxyisochroman-1,3-dione

Participants

Reaction Conditions

Reaction Steps

2-Carboxymethyl-4,6-dimethoxybenzoic acid (60) (3.97 gm) was stirred in toluene (40.0 mL) at ambient temperature in a 100 mL flask with magnetic stirring. Acetic anhydride (1.72 mL) was added and the mixture heated to 110° C. Monitoring by HPLC revealed that the reaction was complete within 2.5 hours. Heat was then removed. Crystallization of 6,8-dimethoxyisochroman-1,3-dione (25) occurred as the solution cooled. The mixture was cooled to 2° C. After a short hold time, yellow crystalline solids were filtered, washed with fresh toluene and then dried on high vacuum. 6,8-Dimethoxyisochroman-1,3-dione (25) (3.05g) was isolated as a yellow crystalline solid.

Provenance & Evidence