Yield:37978-61-3 92%

Reaction Conditions:

with potassium acetate in acetic anhydride at 140; for 0.25 h;

Steps:

14 Method 14; 2-METHYL-4-ACETOXY-6-METHOXYCARBONYLBENZOFURAN

A mixture of E-3-METHOXYCARBONYL-4- (5-METHYLFUR-2-YL)-BUT-3-ENOIC acid (Method 15; 1.39g, 6.2 mmol) and potassium acetate (620mg, 6.3 mmol) in acetic anhydride (12.5 ml) was heated at 140C for 15 mins. The reaction mixture was cooled and poured on to a water/ethyl acetate mixture; the aqueous layer was separated and the organic layer washed sequentially with saturated sodium bicarbonate solution and brine, dried (MGS04) and evaporated IN VACUO to yield the crude product as a dark crystalline mass. This was chromatographed (50g Bondelut, eluting with hexane containing ethyl acetate, 0-100%) to give the title compound as a pale yellow solid, 1.42g (92%). NMR : 2.36 (s, 3H), 3.34 (s, 3H), 3.87 (s, 3H), 6.68 (s, 1H), 7.56 (s, 1H), 7.96 (s, 1H); m/z 247 (M-H)-, 97. 1% by LC-MS.

References:

WO2004/46139,2004,A1 Location in patent:Page 27