A stereoselective total synthesis of the novel triquinane sesquiterpene cucumin E

A total synthesis of cucumin E, a recently isolated triquinane natural product with a new carbon framework, has been achieved. The key step is the flash vacuum pyrolysis (FVP)-induced cyclobutane fragmentation in a readily available pentacyclic caged dione to deliver the triquinane skeleton with functionalization in all the three five-membered rings suitable for further elaboration to the natural product

Total synthesis of the bicyclo[6.3.0]undecane-based sesquiterpene (±)-asterisca-3(15),6-diene. Revision of the relative stereochemistry of the natural product

The first total synthesis of the novel bicyclic sesquiterpene hydrocarbon asterisca-3(15),6-diene is reported. As a consequence, the natural product is shown to possess structure 4 with a trans-5,8 ring fusion and not the previously assigned cis-asterisca-3(15),6-diene 3

Studies towards the total synthesis of novel dolabellane-type diterpenoids: construction of the 5,11-fused bicyclic framework

An oxy-Cope protocol has been grafted on to a previously crafted hydroazulenic system to provide a facile entry into the 5,11-fused bicyclic skeleton present in the novel neodolabellane diterpenoids. Formation of a novel tricyclic diterpenoid framework, generated through a transannular cyclization in the 11-membered ring present in the neodolabellane skeleton and embodying a bridged cycloheptatriene moiety, has also been encountered

A total synthesis of guanacastepene C

A total synthesis of the structure corresponding to the novel tricyclic diterpene guanacastepene C has been realized in which a Knoevenagel cyclization serves as a key step to annulate the six-membered C-ring on a stereochemically secured bicyclic hydroazulene precursor

Total synthesis of the putative structure of the novel triquinane natural product isocapnellenone

A total synthesis of the 'putative structure' 7, attributed to the novel triquinane sesquiterpene isolated recently from two Buddelia species has been accomplished. The spectral data for 7 is a complete mismatch with those reported for the natural product and warrants a revision of the assigned structure

Stereoselective synthesis of the naturally occurring 2-pyranone dodoneine

The first total synthesis of the naturally occurring dihydropyranone dodoneine is reported. Asymmetric allylations were used for the stereoselective generation of the two stereogenic centers. The pyranone ring was created by means of a ringclosing metathesi

Studies toward the Total Synthesis of Diterpene Antibiotic Guanacastepene A: Construction of the Hydroazulenic Core

As a part of studies aimed toward the total synthesis of biologically important natural product guanacastepene A of contemporary interest,a new and concise route to a fully functionally endowed hydroazulenic core is delineated. The strategy involves the building of the requisite stereochemical features on a endo-tricyclo[5.2.1.02,6]decane matrix and excision of the five-membered ring through a retro-Diels-Alder reaction.Generation of the seven-membered ring to access the hydroazulenic framework was achieved employing ring closure metathesis (RCM)reaction as the key step

Ruthenium mediated oxidative fragmentation of the pinane system : An entry into chiral bicyclo [4.2.0]octanes

1163-1165 (-)-α-Pinene has been restructured in three steps to functionalized bicyclo[4.2.0]octanes via cyclobutane annulation to the tricyclo- [5.1.1.02,5]nonane system and a novel RuO4 mediated oxidative fragmentation

A stereoselective total synthesis of the novel triquinane sesquiterpene cucumin E

A total synthesis of cucumin E, a recently isolated triquinane natural product with a new carbon framework, has been achieved. The key step is the flash vacuum pyrolysis (FVP)-induced cyclobutane fragmentation in a readily available pentacyclic caged dione to deliver the triquinane skeleton with functionalization in all the three five-membered rings suitable for further elaboration to the natural product