The related nine-membered oxacycles eicosanoid oxylipins, (À)-halicholactone
114 and (À)-neohalicholactone, were isolated from the marine sponge Halichondria
okadai (Kadota) collected from Daiozaki, Japan [104]. Halicholactone 114 exhibited
weak inhibitory activity against farnesyl protein transferase and lipoxygenase of
guinea pig polymorphonuclear leukocytes.
Two synthetic approaches to (À)-halicholactone 114, involving a RCM as
the key step, were reported by Takemoto et al. [105] and Takahashi et al. [106].
,
Scheme 18 Synthesis of (+)-obtusenyne, 6 by Crimmins et al.
Scheme 19 Synthesis of 106 developed by Kaliappan and Kumar for the preparation of
eleutherobin
Synthesis of Eight- to Ten-Membered Ring Ethers
337
114 and (À)-neohalicholactone, were isolated from the marine sponge Halichondria
okadai (Kadota) collected from Daiozaki, Japan [104]. Halicholactone 114 exhibited
weak inhibitory activity against farnesyl protein transferase and lipoxygenase of
guinea pig polymorphonuclear leukocytes.
Two synthetic approaches to (À)-halicholactone 114, involving a RCM as
the key step, were reported by Takemoto et al. [105] and Takahashi et al. [106].
,
Scheme 18 Synthesis of (+)-obtusenyne, 6 by Crimmins et al.
Scheme 19 Synthesis of 106 developed by Kaliappan and Kumar for the preparation of
eleutherobin
Synthesis of Eight- to Ten-Membered Ring Ethers
337