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Paper | Regular issue | Vol 53, No. 6, 2000, pp.1269-1283
Published online, 1st January, 1970
DOI: 10.3987/COM-00-8851
Conformation and Configuration of Humulene Di- and Triepoxides Generated from Four Possible Conformations of Humulene 9,10-Epoxide

Kiyoharu Hayano* and Katsura Mochizuki

*Chemistry Laboratory, Hokkaido College of Education, Ainosato, Sapporo 002-8502, Japan

Abstract

The complete reaction of humulene 9,10-epoxide (1) with m-CPBA produced a hitherto unknown 2R*, 3R*, 6S*, 7S*, 9S*, 10S*-humulene 2,3;6,7;9,10-triepoxide (6) together with three known triepoxides (7, 8 and 9) in the ratio of 6 : 7 : 8 : 9 = 1.3 : 11.5 : 22.6 : 64.6. The configuration of 6 was determined by X-Ray crystallography. Intermediate products of the epoxidation reaction, two humulene 6,7;9,10- {(2E)-6R*, 7R*, 9S*, 10S* (2) and (2E)-6S*, 7S*, 9S*, 10S* (3)} and two 2,3;9,10-diepoxides {(6E)-2S*, 3S*, 9S*, 10S* (4) and (6E)-2R*, 3R*, 9S*, 10S* (5)} were also produced in the ratio of 2 : 3 : 4 : 5 = 41 : 18 : 35 : 6), and these main conformations (CT, CC, CT and TC) were first determined by X-Ray crystallography (for 3 and 4) and NMR spectroscopy (for 2 and 5). The triepoxide (6) maintained the configuration corresponding to the less stable TT conformation of 1 and the minor TT conformation of 3 and 5.