An approach to the synthesis of pimpinellin
Although pimpinellin has been known for many years, synthesis of the compound has not been reported. A useful intermediate toward the synthesis of pimpinellin would be 2-carboxy-6-methoxy-4,7-benzofurandione or its ester. These have been synthesized from pyrogallol in an eight step synthesis via methyl 4,6,7-trimethoxy-coumarilate. However, there is some question of the structure of two of the intermediate compounds in this sequence. The projected approach was to attempt to form this same benzofurandione in fewer steps from the same starting material by oxidation of the more readily available 6,7-dimethoxycoumarilic acid or its ester. Neither this acid nor its ester formed the quinone on oxidation with nitric acid nor lead tetraacetate, but underwent nitration instead. The 5-bromo acid and ester were not oxidized with nitric acid. Selective demethylation of the 7- methoxy group of 6,7-dimethoxycoumarilic acid was attempted. Fremy's salt or lead tetraacetate might be used to oxidize this cleavage compound to the corresponding 4,7-quinone. Unfortunately, the cleavage product was not obtained.
College and Department
Chemistry and Biochemistry
BYU ScholarsArchive Citation
Yuan, Andrew Meau, "An approach to the synthesis of pimpinellin" (1972). Theses and Dissertations. 8504.