Superacid cyclization of certain aliphatic sesquiterpene derivatives in ionic liquids

Abstract

R a R 1, 3 7, 9 8 2 OAc OH a OAc 10 4 CO 2 CH 3 CO 2 CH 3 + CO 2 R 11: R = CH 3 12: R = H 11, 12 a, b [bmim]BF 4 = N N BF 4 _ [bmim]PF 6 = N N PF 6 _ 5 6 1, 7: R = OH 3, 9: R = SO 2 Ph Superacid cyclization was demonstrated for the first time to be successful in those ionic liquids with functional groups that are stable in the reaction medium using aliphatic sesquiterpene derivatives as examples.

Natural sesquiterpenoids

“…19 A study of the superacid cyclisation of certain aliphatic sesquiterpene derivatives in ionic liquids has been carried out. 20 Several sesquiterpenoids, isolated from Ferula fukanensis, have been shown to inhibit nitric oxide production by a murine macrophage-like cell line. 21…”

Superacid cyclization of (2E,6E,10E,14E)-8-phenylsulfonylgeranylfarnesol tetrahydropyranyl ether

“…The structures of 8 and 9 were established using spectral data. The optically active form of 9 was also confirmed by retrosynthesis from (+)-sclareolide (10).Biomimetic superacid cyclization of terpenoids turned out to be an effective synthetic method for cyclic terpenoids [1][2][3][4][5][6][7][8]. We studied previously superacid cyclization of several α,ω-bifunctionalized mono-and sesquiterpenoids and showed that α,ω-geraniol derivatives gave cyclic products with the n-menthane structure [9] whereas α,ω-bifunctionalized sesquiterpenoids produced monocyclic derivatives of α-cyclogeraniol prenylated at the gem-dimethyl group, which were formed by initiation of the cyclization by protonation of the inner C-6-C-7 double bond [10].…”