Pyrrolidine → Dimethyl 3,4-Dihydro-2,2-dimethyl-4-oxo-2H-1-benzopyran-6,7-dicarboxylate

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Reaction Steps

In 100 ml of acetone was dissolved 4.2 g of dimethyl 4-acetyl-5-hydroxyphthalate synthesized in accordance with the process of Bulletin of the Chemical Society of Japan, Vol. 57, p. 3221 (1984). To the solution were added 1.0 ml of pyrrolidine and a small amount of Molecular Sieve (3A), followed by stirring at room temperature for 3 days. Any insoluble material was removed by filtration, and the solvent was removed by distillation under reduced pressure. The residue was purified by silica gel column chromatography to obtain 4.6 g (86.3%) of a yellow oily substance.

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