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Progress toward a convergent approach for the enantioselective synthesis of the Veratrum alkaloid jervine is presented. The two requisite fragments were stereoselectively and efficiently fashioned from economical and readily available reagents. Key reactions include (a) a highly diastereoselective Ireland—Claisen rearrangement to establish the necessary cis-relationship between the amine and methyl group on the tetrahydrofUran E-ring; (b) a diastereoselective selenoetherification reaction that enabled the assembly of the D/E oxaspiro [4.5] decene in the needed configuration; and (c) an enzymatic desymmetrization of an abundant achiral diol en route to a key four-carbon building block as a practical alternative to a protected Roche ester reduction.

Emeriones A–C (1–3), three highly methylated polyketides with bicyclo[4.2.0]octene and 3,6-dioxabicyclo[3.1.0]hexane functionalities, were isolated from Emericella nidulans. An additional peroxide bridge in compound 3 led to the construction of an unexpected 7,8-dioxatricyclo[4.2.2.02,5]decene scaffold. The structures of 1–3 were elucidated by comprehensive spectroscopic techniques, and their absolute configurations were confirmed by single-crystal X-ray crystallographic analyses and ECD calculations. Compound 1 shows weak inhibitory effects on NO production in LPS-induced RAW264.7 cells.

The highly strained tricyclo[5.2.1.0(1,6)]decene skeleton of solanoeclepin A was synthesized through two key C-C bond forming processes; thus, a Hg(TFA)2-mediated oxymercuration followed an intramolecular aldol reaction to B and a SmI2-mediated cyclization of C between an aldehyde and an unsaturated ester to form the cyclobutane D having a tricyclo[5.2.1.0(1,6)]dodecene.

The stereocontrolled synthesis of the highly strained, tricyclo[5.2.1.0(1,6)]decene skeleton (C) of solanoeclepin A has been achieved through two key transformations: a [2,3]-Wittig rearrangement of allylpropargyl ether (A) to propargyl alcohol (B) having a trans-fused perhydroindane framework and the formation of the cyclobutane via a cobalt-mediated Hosomi-Sakurai type cyclization of an acetylene dicobalthexacarbonyl complex.

The construction of a new type of bicyclo[4.4.0]decene products with a conjugated exocyclic diene unit was developed using Rh-catalyzed cyclization of 1,5-bisallenes in the presence of monoallenes. The steroid-like tetracyclic products could be obtained by applying an alkylation−Diels−Alder process.

The first, enantiocontrolled total synthesis of (+)-sundiversifolide has been accomplished using the sequential ring-closing metathesis, [3,3]-sigmatropic rearrangement, and iodolactonization for the key assembly of the cis-fused oxabicyclo[5.3.0]decene framework of the natural product. [structure: see text]