Cyclopropene sterols

Figure 19.29 Biosynthesis of cyclopropenic sterols by sponges of the genus Calyx.

Phloeodictyidae 80-100 100-110 Calyx, Oceanapia, Pellina Acetylenic derivatives, cyclopropanic et cyclopropenic sterols for the genus Calyx, a, m-di-thiocyanates, heterocycles. 

More than twenty sterols with cyclopropanes or cyclopropenes have been isolated from marine organisms [53], The majority of these come from sponges, although significant numbers have been isolated from dinoflagellates and co-elenterates. There are no terrestrial organisms known to contain such sterols and thus their biosynthesis is purely a marine problem. 

Calysterol (25) is a C29 cyclopropene-containing marine sterol isolated from the sponge Calyx nicaensis. The presence in calysterol of a cyclopropene ring suggests that in marine organisms sterols with unusual side chains may be quite widespread. 

An extract of Calyx nicaensis has provided the three biologically active cyclopropene-containing marine sterols (28R)-calysterol (4), (23R)-23H-isocalysterol (5) and (24S)-24H-isocalysterol (6) " Whilst calysterol (4) is the major isomer and the first of the series to... 

Sterol from the Mediterranean sponge Calyx nicaen-sis containing the unusually reactive cyclopropene structure. C29H46O, Mr 410.68, mp. 114-116°C, [aJo ... 

Li, L.N., H. Li, R.W. Lang, T. Itoh, D. Sica, and C. Djerassi Minor and Trace Sterols in Marine Invertebrates. 31. Isolation and Structure Elucidation of 23 H-Isocalysterol, a Naturally Occurring Cyclopropene. Some Comparative Observations on the Course of Hydrogenolytic Ring Opening of Steroidal Cyclopropenes and Cyclopropanes. J. Am. Chem. Soc. 104, 6726 (1982). 

Sterols and Stands with Cyclopropanic and Cyclopropenic Side Chains... 

Figure 19.25 Sterols and stands with cyclopropenic side chains.

Doss, G.A. and Djerassi, C. (1988) Sterols of marine invertebrates. 60. Isolation and structure elucidation of four new steroidal cyclopropenes from the sponge Calyx podatypa. J. Am. Chem. Soc., 110, 8124-8128. 

Doss, G.A., Silva, C.J., and Djerassi, C. (1989) Biosynthetic studies of marine lipids. 22. Calysterol some aspects of sterol cyclopropene biosynthesis in the sponge Calyx nicaeensis. Tetrahedron. 45, 1273-1282. 

Itoh, T., Sica, D., and Djerassi, C. (1983a) Minor and trace sterols in marine invertebrates. 36. (24S)-24(H)-lsocalysterol a new steroidal cyclopropene from the marine sponge Calyx niceaensis. J. Org. Chem., 48,890-892. 

Kurek-Tyrlik, A., Minksztym, K., and Wicha, J. (1995) Synthesis of (23R)- and (23S)-23H-isocalysterols. The first synthesis of a representative of marine sterols with a cyclopropene moiety in the side chain. J. Am. Chem. Soc., 117, 1849-1850. 

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