TY - JOUR
T1 - Attempted acid-catalyzed transannular reactions in the cembranoids
AU - Czarkie, D.
AU - Carmely, S.
AU - Groweiss, A.
AU - Kashman, Yoel
PY - 1985
Y1 - 1985
N2 - Several cembrane diterpenes were treated by various acids under different experimental conditions. All tested compounds were found to be acid sensitive, leading either to local chemical transformations (e.g. opening of epoxides), to transannular reactions and/or to unidentified mixtures. Sarcophine (7), the principal cembrane tested, was found to afford either all types of possible epoxide opening products (11-22), or, by a transannular reaction, when treated with SnCl4, two tetrahydrooxepine derivatives (23 and 24). The structure determination of the various derivatives of sarcophine was based mainly on the 1H and 13C-NMR spectra and also on several chemical transformations. Flaccidoxide (8), another cembranoid examined, was found to yield, with Zn/Cu couple, the expected deoxygenation product (sarcophytol-B, 32) together with an unexpected transannular reaction product (33). The structure, including the stereochemistry, of the latter THF-derivative of 8 (33) was elucidated by NMR and chemical reactions.
AB - Several cembrane diterpenes were treated by various acids under different experimental conditions. All tested compounds were found to be acid sensitive, leading either to local chemical transformations (e.g. opening of epoxides), to transannular reactions and/or to unidentified mixtures. Sarcophine (7), the principal cembrane tested, was found to afford either all types of possible epoxide opening products (11-22), or, by a transannular reaction, when treated with SnCl4, two tetrahydrooxepine derivatives (23 and 24). The structure determination of the various derivatives of sarcophine was based mainly on the 1H and 13C-NMR spectra and also on several chemical transformations. Flaccidoxide (8), another cembranoid examined, was found to yield, with Zn/Cu couple, the expected deoxygenation product (sarcophytol-B, 32) together with an unexpected transannular reaction product (33). The structure, including the stereochemistry, of the latter THF-derivative of 8 (33) was elucidated by NMR and chemical reactions.
UR - http://www.scopus.com/inward/record.url?scp=33746589279&partnerID=8YFLogxK
U2 - 10.1016/S0040-4020(01)96472-5
DO - 10.1016/S0040-4020(01)96472-5
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AN - SCOPUS:33746589279
SN - 0040-4020
VL - 41
SP - 1049
EP - 1056
JO - Tetrahedron
JF - Tetrahedron
IS - 6
ER -