Synthetic approaches to bicyclo[5.3.0]decane sesquiterpenes

A total synthesis of (−)-hortonone C

“…Several approaches for the stereoselective construction of 5,7 cis-fused bicyclic systems are known in the literature. 6 The most commonly employed methods include intramolecular aldol reactions, 7 ring-closing metatheses, 8 and metal-catalyzed cycloisomerizations. 9 In addition, ring expansion strategies are well precedented.…”

Interception of a Rautenstrauch Intermediate by Alkynes for [5+2] Cycloaddition: Rhodium‐Catalyzed Cycloisomerization of 3‐Acyloxy‐4‐ene‐1,9‐diynes to Bicyclo[5.3.0]decatrienes

“…The cycloheptatriene in the resulting bicyclic system has three well-differentiated double bonds ready for further functionalization. [19] Cycloheptatrienes themselves are also widely present in polycyclic natural products and pharmaceutical agents. [23] Further studies to uncover the details of the mechanism, expand the scope of the reaction, and apply this novel cycloisomerization to the synthesis of natural products and pharmaceutical agents are currently in progress.…”

“…3.0]decane skeletons are present in many natural products. [19] Besides the Rautenstrauch rearrangement to form fivemembered rings, a number of other pathways may also compete with the desired cycloisomerization of enyne 7 to the bicyclic compound 8. For example, if a carbene intermediate similar to 5 is generated, it may undergo cyclopropanation or cyclopropenation with alkenes or alkynes in the system.…”

NMR Studies on [2 + 3] Cycloaddition of Nitrile Oxides to Polyunsaturated Medium Size Rings

“…Many sesquiterpenes display biological activity including antimicrobial, antitumor and cytotoxic properties. 19 Some bisnor-sesquiterpenes exhibit allelopathic activity. 20 Herein we present results of our research concerning site selectivity, regioselectivity and stereoselectivity of 1,3-dipolar cycloaddition of 4-trifluoromethylbenzonitrile oxide to polyunsaturated medium rings including 1 1 -m e m b e r e d s e s q u i t e r p e n e s 5 , 8 a n d 1 0 , 1,5,9-cyclododecatriene (13), 1,3-cyclooctadiene (18) and 5-vinyl-2-norbornene (21) envisaging to obtain new biologically active compounds.…”