3-HMP is prepared from 3-methylphthalide (3-MP), which is in turn prepared from 2-acetylbenzoic acid (ABA). The ketone of the chain form of ABA (I) is reduced (II) by dissolving ABA (Aldrich, Montreal) in 100 ml of methanol containing 0.4 g of sodium hydroxide followed by the addition of sodium borohydride (0.4 g) and stirring for 18 h. After evaporation down to 10 ml, the Iactone is formed (III) by adding 100 ml of distilled water and then acidifying the mixture to pH 1 with 6N hydrochloric acid. Three chloroform extracts (50 ml) of the reaction mixture are pooled and evaporated to dryness, yielding a clear oil with a characteristic pepper-like aroma. The oil is distilled in a microdistillation apparatus. 3-MP can be stored for up to 60 days at 4 C in the dark. After this time, the product of oxidation, 3-HMP, can be found. Almost complete con version of 3-MP to 3-HMP occurs within 365 days when stored at room temperature and in the presence of sunlight. 3-HMP can also be prepared from 3-MP by dissolving 3-MP in benzene and bubbling oxygen through the stirring mixture under light from a mercury Iamp or short UV wave source. 3-HMP can be separated from 3-MP by preparative TLC using silica gel plates and 15% ether in petroleum ether (b.p. 35-60 C) for development. Compounds can be visualized using an anisaldehyde stain and 3-HMP can be eluted from the silica gel with ether to yield a white amorphous powder. 3-HMP has a smaller Rf than 3-MP and stains deep red-purple compared to white for 3-MP.

3-HMP is prepared from 3-methylphthalide (3-MP), which is in turn prepared from 2-acetylbenzoic acid (ABA). The ketone of the chain form of ABA (I) is reduced (II) by dissolving ABA (Aldrich, Montreal) in 100 ml of methanol containing 0.4 g of sodium hydroxide followed by the addition of sodium borohydride (0.4 g) and stirring for 18 h. After evaporation down to 10 ml, the Iactone is formed (III) by adding 100 ml of distilled water and then acidifying the mixture to pH 1 with 6N hydrochloric acid. Three chloroform extracts (50 ml) of the reaction mixture are pooled and evaporated to dryness, yielding a clear oil with a characteristic pepper-like aroma. The oil is distilled in a microdistillation apparatus. 3-MP can be stored for up to 60 days at 4 C in the dark. After this time, the product of oxidation, 3-HMP, can be found. Almost complete con version of 3-MP to 3-HMP occurs within 365 days when stored at room temperature and in the presence of sunlight. 3-HMP can also be prepared from 3-MP by dissolving 3-MP in benzene and bubbling oxygen through the stirring mixture under light from a mercury Iamp or short UV wave source. 3-HMP can be separated from 3-MP by preparative TLC using silica gel plates and 15% ether in petroleum ether (b.p. 35-60 C) for development. Compounds can be visualized using an anisaldehyde stain and 3-HMP can be eluted from the silica gel with ether to yield a white amorphous powder. 3-HMP has a smaller Rf than 3-MP and stains deep red-purple compared to white for 3-MP.

3-HMP is prepared from 3-methylphthalide (3-MP), which is in turn prepared from 2-acetylbenzoic acid (ABA). The ketone of the chain form of ABA (I) is reduced (II) by dissolving ABA (Aldrich, Montreal) in 100 ml of methanol containing 0.4 g of sodium hydroxide followed by the addition of sodium borohydride (0.4 g) and stirring for 18 h. After evaporation down to 10 ml, the Iactone is formed (III) by adding 100 ml of distilled water and then acidifying the mixture to pH 1 with 6N hydrochloric acid. Three chloroform extracts (50 ml) of the reaction mixture are pooled and evaporated to dryness, yielding a clear oil with a characteristic pepper-like aroma. The oil is distilled in a microdistillation apparatus. 3-MP can be stored for up to 60 days at 4 C in the dark. After this time, the product of oxidation, 3-HMP, can be found. Almost complete con version of 3-MP to 3-HMP occurs within 365 days when stored at room temperature and in the presence of sunlight. 3-HMP can also be prepared from 3-MP by dissolving 3-MP in benzene and bubbling oxygen through the stirring mixture under light from a mercury Iamp or short UV wave source. 3-HMP can be separated from 3-MP by preparative TLC using silica gel plates and 15% ether in petroleum ether (b.p. 35-60 C) for development. Compounds can be visualized using an anisaldehyde stain and 3-HMP can be eluted from the silica gel with ether to yield a white amorphous powder. 3-HMP has a smaller Rf than 3-MP and stains deep red-purple compared to white for 3-MP.