@article{997fcc7b1b58448a907db0915b8b4198,
title = "Cannabielsoic acids. Isolation and synthesis by a novel oxidative cyclization",
abstract = "Two tricyclic dihydrobenzofuran cannabinoids, cannabielsoic acids A (4a) and B (5a) were isolated from hashish. Their structures were elucidated by chemical transformations and from spectral data. Cannabielsoic acid A was synthesized from cannabidiolic acid by an oxidative cyclization in the presence of air under irradiation, or with manganese dioxide.",
author = "A. Shani and R. Mechoulam",
note = "Funding Information: The crystalline cannabielsic acid B, methyl ester (Sb). m.p. 5860” has the same molecular weight as 4b and an almost identical NMR spectrum. However, the proton signal of the acetylable OH group appears at 5-75. We interpret this difference as indicating that in 4Jr the carbomethoxyl group is adjacent and H-bonded to the phenolic OH, while in Sb it is adjacent to the ether-k oxygen. This is supported by IR data. In 4a the CO of the carboxyl group is at 1630 cm{\textquoteright} {\textquoteright} while in 5a it is at 1725 cm {\textquoteleft}; in 4b it is at 166Ocm-{\textquoteright} while in Sb it is at 1720cm {\textquoteleft}. The same phenomenon has been observed{\textquoteright} in the IR spectra of THC acids A (3s) and B (3b). In the former (3a) the carboxyl group CO absorbs at l615cm-{\textquoteright} whik in the later (3b) it is at 1710cm {\textquoteleft}. We have suggested that in 3b there is loss of",
year = "1974",
month = jan,
day = "1",
doi = "10.1016/S0040-4020(01)97114-5",
language = "English",
volume = "30",
pages = "2437--2446",
journal = "Tetrahedron",
issn = "0040-4020",
publisher = "Elsevier Ltd.",
number = "15",
}