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With sodium tetrahydroborate In tetrahydrofuran; acetic acid at 50℃; for 2h;
With hydrogenchloride; acetic acid; zinc
reduction;
With sodium tetrahydroborate In tetrahydrofuran at -10 - 0℃; for 2h; Yield given. Yields of byproduct given;
With tetrabutylammonium borohydride In tetrahydrofuran for 4h; Ambient temperature; Yield given. Yields of byproduct given. Title compound not separated from byproducts;
With sodium tetrahydroborate In tetrahydrofuran for 2h; Heating; Yield given. Yields of byproduct given;
With L-Selectride In tetrahydrofuran at -78 - -30℃; for 2h; Yield given. Yields of byproduct given;
With L-Selectride In tetrahydrofuran for 2h; Ambient temperature; Yield given. Yields of byproduct given;
With lithium borohydride In tetrahydrofuran at -10 - 20℃; for 2h; other 3-substituted phthalic anhydrides; var. reducing agents and reaction conditions;
With sodium tetrahydroborate Yield given; Yields of byproduct given;
With water; calcium carbonate; In 1,4-dioxane; at 85℃; for 4h;
The methyl 2-(bromomethyl)-benzoate (1 equiv) was diluted with dioxane (2.6 mL per mmol of methyl-2-(bromomethyl)-benzoate) and H2O (2.6 mL per mmol of methyl-2-(bromomethyl)-benzoate). CaCO3 (5-10 equiv) was added and the reaction was heated to 85 C for 4-27 h. Residual calcium carbonate was filtered off and the filter cake was washed with EtOAc and H2O. Thefiltrate was partitioned and the organics were extracted with EtOAc, combined, dried over MgSO4 and concentrated in vacuo to afford the desired lactone.
95%
With calcium carbonate; In 1,4-dioxane; water; at 85℃; for 3.5 - 4h;
1.8 Preparation of 4-methoxy-3H-isobenzofuran-1-one In a 500 mL round bottom flask was added 15.15 g (0.0585 mol) of 2-bromomethyl, 3-methoxy methyl benzoate, 29.3 g (0.293 mol) of CaCO3, 150 mL of dioxane and 150 mL of water. The flask was placed into an oil bath and the mixture heated with stirring at 85 C. for 3.5 to 4 hours. The CaCO3 was filtered off and washed with ethyl acetate and water. To the filtrate was added ethyl acetate (200 mL) and water (50 mL) and the mixture then shaken in separatory funnel. The water phase was extracted twice with ethyl acetate (50 mL). The ethyl acetate extracts were combined, extracted once with water, dried over MgSO4, and evaporated. This yielded 9.2 g of white crystals of 7-methoxybenzolactone (95% yield). 1H NMR (CDCl3, 300 MHz) delta (ppm): 7.5 (m, 2H), 7.1 (m, 1H), 5.26 (s, 2H), 3.93 (s, 3H). TLC: Rf=0.46 (1:1 EtOAC: hexane).