The synthesis of racemic tremetone

The Benzofurans of Isocoma wrightii. Structure and Stereochemistry

“…The latter was acylated wdth acetic acid and trifuoroacetic anhydride to give 2-(2,3-dihydro-5-acetylbenzofuryl)-2-propvl acetate, mp 95°, rpt. mp 95-96° ( 35), in overall yield of 30%. The latter acetate was pyrolyzed at 330°a ccording to Bonner's procedure (36) to give racemic tremetone in quantitative yield.…”

“…The chloroform was then removed in vacuo to give a greenish-brown tar residue (205 g) designated fraction C. Fraction C was partitioned between two liters each of hexane and aqueous methanol (1:9). The hexane layer was concentrated to a green syrup (35 g) and designated fraction D. The aqueous methanol layer was concentrated to 0.5 liter and then one liter of water was added. After the addition of salt to prevent an emulsion, the mixture was extracted with two liters of chloroform.…”

“…Treatment of 2-acetylbenzofuran wdth methyl magnesium iodide, as described by Bonner et al (35), yielded 2-benzofuryl-2-propanol, which was then hydrogenated wdth W-2 Raney nickel catalyst to give 2-(2,3-dihydrobenzofuryl)-2-propanol. The latter was acylated wdth acetic acid and trifuoroacetic anhydride to give 2-(2,3-dihydro-5-acetylbenzofuryl)-2-propvl acetate, mp 95°, rpt.…”

“…Synthesis of 2,3-dihydrobenzofurans such as tremetone (1) also seems to be readily7 accom-'Screening by7 NCI of the National Institutes of Health. plished (35,36). On the other hand, synthesis of 2,3-dihydrobenzofurans containing an oxygen substituent at C-3, such as toxol (4), has not appeared in the literature.…”