Synthesis of Polyquinane Natural Products:  An Update

Thermal transformation of 1σ and 1β-endo and exo- dicyclopentadienyl vinyl ethers (competitive Claisen and Cope systems)

“…Linear triquinanes are an important class of sesquiterpene natural products possessing the fused cis-anti-cis [6.3.0.0 2,6 ]-undecane carbon skeleton. Some of these compounds have antitumour and antibiotic properties and hence there are many reports on their synthesis 1 . As one of the approaches for the synthesis of linear triquinanes, cis-anti-cis and cissyn-cis, we sought to investigate the Claisen rearrangement of vinylethers 1a and 1b.…”

Synthesis of a Highly Functionalized Triquinane: Studies Towards a Total Synthesis of Subergorgic Acid and Its Analogues

“…Chemistry of triquinane natural products has been an area of extensive synthetic studies since the mid-1970s [1][2][3][4]. Subergorgic acid is an angular sesquiterpene triquinane with a silphiperfolane skeleton (1) [5,6].…”

“…The bifunctional reagent (7), developed by Piers' group [10,11], corresponds to the 1-butene d 2 ,a 4 -synthon (8) as it includes a nucleophilic center at the C-2 (d 2 -synthon) and an electrophilic center at the C-4 (a 4 -synthon). The reagent (7) is useful for carrying out methylenecyclopentane annulations as it undergoes efficient Cu(I)-catalyzed 1,4-addition to enones [10] followed by cyclization of the intermediate chloroketone.…”

“…Therefore, triquinane (9), along with its precursors, allows for the functionalization of any carbon atom on an angular triquinane skeleton. Thus (9) represents an important intermediate in synthesis of naturally occurring triquinanes such as subergorgic acid (2) and its analogues (3)(4)(5)(6) [5,6]. …”

Crystal Structure of 2-Ethoxy-6,13-dimethoxy-12-methyl-11-phenyl-9,11,13,15-tetraazatetracyclo[7.6.0.01,12.03.8]pentadeca-3,4,6-triene-10,14-dione

“…1 During the course of our continuous investigation on stereoselective syntheses of hetero angular polyquinane analogues from active urazoles (1a-b) 2 , we isolated an intricate cyclic bisurea including an indoline skeleton (title compound, 2) by an alkali-treatment of photoadduct (3) of 1b with ethanol. Since the 1 H and 13 C-NMR analyses did not permit an identification of the framework and the stereochemistry of 2, the crystal structure was determined by an X-ray analysis.…”