Synthesis of Clerodane Diterpenoids and Related Compounds - Stereoselective Construction of the Decalin Skeleton with Multiple Contiguous Stereogenic Centers

Abstract

Stereoselective construction of contiguous stereogenic centers in the decalin ring -usually four -is central to the synthesis of clerodane diterpenoids and the present review surveys the methods utilized to meet this task. Major strategies for the stereocontrol are: (i) diastereoface-selective reactions on a rigid ring, (ii) conformational preference of a rigid ring structure in an equilibrium condition, and (iii) diastereoselective cyclization. According to the classification based on the methods for construction of the stereogenic centers, an overview will be presented to various synthetic studies on clerodane and related natural products, which are of current interest in view of biological activity. Use of Oxy-Cope Reactions 6.2 Use of Stereocontrolled Ring-Closure Reactions 7Concluding Remarks

Enantioselective synthesis of dictyoceratin-A (smenospondiol) and -C, hypoxia-selective growth inhibitors from marine sponge

“…10 One of the most popular strategy for the synthesis of transclerodane type compounds is that the quinone/phenol side chain is appended through one-pot Birch reduction-alkylation on the enone moiety of Wieland-Miescher-type diketone. 11 On the other hand, Samadi and co-workers developed a concise and scalable synthetic method of ilimaquinone (3) through appending the side chain by simple alkylation toward the enone 5. 12 We envisioned that the similar strategy, as shown in Figure 2, would lead us to obtain sufficient amount of the compounds.…”

Clerodane diterpenes: sources, structures, and biological activities

“…1, four types of clerodane skeletons are defined with respect to the configuration at the ring fusion and of the substituents at C-8 and C-9: trans–cis (TC), trans–trans (TT), cis–cis (CC), and cis–trans (CT). 5 In the majority of clerodanes, the C-17 and C-20 substituents on C-8 and C-9 are cis . 5 …”

Feeding Deterrent Activity of Terpenoid Lactones with the <I>p</I>-Menthane System Against the Colorado Potato Beetle (Coleoptera: Chrysomelidae)

“…Structural changes in an antifeedant molecule may affect the activity in different manners for different species (Menn 1983, Blaney et al 1987, Ló pez-Olguṍn et al 1999, González-Coloma et al 2002, Labbé et al 2005. The application of natural antifeedants for plant protection is limited by their low concentration in plants and their complicated chemical structures that are difÞcult to synthesize (Ley and Toogood 1990, Lawrencet 2000, Tokoroyma 2000. Synthetic antifeedants, which can be more or less "true" structural analogs of natural ones, can offer another option for practical application.…”