Synthesis of tetracyclo[6.3.0.04,11.05,9]undeca-2,6-diene, 10-oxatetracyclo[6.3.0.04,11.05,9]undeca-2,6-diene, and hexacyclo[5.4.0.02,6.04,11.05,9.08,10]undecane. Structure of syn-4, syn-7-diiodopentacyclo[6.3.0.02,6.03,10.05,9]undecane. Synthesis and rhodium(I)-promoted rearrangement

A Diels–Alder cycloadduct of methylcyclopentadiene with 2,6-dimethyl-p-benzoquinone and the intramolecular photocyclization product of this cycloadduct

“…The three methyl groups on one side of the molecule lead to an elongation of bonds relative to those of the unsubstituted side. As with most norbornane and norbornene structures, the C(4a)---C(8a) ethane-type bond [1.560(3)A] is elongated (Dallinga & Toneman, 1968;Marchand, Chou, Ekstrand & van der Helm, 1976;Watson, Nagl, Marchand & Deshpande, 1989); however, in (lb) the C(4)--C(4a) distance of 1-564 (3)/~ is statistically equivalent. This lengthening may be attributed to the methyl substituents at C(4a).…”

Efficient synthesis of 4-halo-D3-trishomocubane derivatives

“…Some of them, like bicyclo [1.1.1]pentane or cubane are considered to be key bioisosteres of traditional flat aromatic systems. 2,3 D3-Symmetrical trishomocubane (pentacyclo[6.3.0.0 2,6 .0 3,10 .0 5,9 ]undecane) has attracted particular attention, because it has specific properties valuable for novel drug design, viz., a relatively large cage size, high lipophilicity, and a conformational rigidity. Actually, around fifty derivatives of D3-trishomocubane have been tested against 5-HT, adenosine A1, DAT1, dopamine and as NMDA receptors and some of them indeed display pronounced activity.…”

“…7 However, despite the fact that D3-trishomocubane derivatives have great potential for drug discovery, their syntheses often remain tricky and the mechanisms of the transformations are still unclear. In particular, rearrangement of Cs-trishomocubane-8,11-diol 1 in acidic media, which is the main method of synthesis of 4,7disubstituted D3-trishomocubanes, leads to a mixture of products, and the ratio of them strongly depends on the conditions [8][9][10] . Thus, the result of the interaction of diol 1 with hydrobromic or hydroiodic acid at 100 o C is the formation of a mixture of hexacyclic ether 2 and 7-halo-D3-trishomocubane-4-ol diastereomers 3a,b or 4a,b.…”

The reaction of potassium iodide in polyhydrogen fluoride – pyridine with two cage diols. A simple synthesis of tetracyclo[6.3.0.04,11. 05,9]undeca-2,6-diene ("homohypostrophene")

“…Recently three groups (1-3) simultaneously described routes from the diketone 1 (4) to homohypostrophene 6 whence homopentaprismane 8 may be prepared by photocyclization (2,3).…”