Tricyclic Norbornyl Analogs¹

Zur Lenkung der intramolekularen Diels‐Alder‐Reaktion von Cyclopentadienen mit olefinischen Substituenten

“…Synthese des uberbriickten Norbornen-Derivates 7. -Beim Einsatz von Vinylmagnesiumchlorid (3) in Ather bei -60" mit 1/2 isolierten wir als einziges Produkt (43%) das uberbriickte Norbornen-Derivat 7 (nach [ 11 [9] aBrexenon)); Schema 3). Da 7 uber eine IDA-Reaktion des moglichenveise uber 4 gebildeten 5-Cpd-Derivates 5 entstanden sein muss, steht fest, dass die in [8] rnit 0und N-Nukleophilen gefundene Ringoffnungsreaktion von 1/2 auch rnit C-Nukleophilen in Form von Organomagnesium-Verbindungen stattfindet6).…”

P6S5(C4H9)2, the first organophosphorus chalcogen molecule with a brexane skeleton

“…The X-ray structure analysis confirms that the molecule is 5, 8-di-tert-butyl-5,8-dithioxo-2,4,9trithiahexaphosphatricyclo[4.3.0.03'7]nonane. The skeleton of the molecule, which is the first P-S analogue of the tricyclic brexane (Nickon, Kwasnik, Swartz, Williams & DiGiorgio, 1965), is formally derived from a norbornane-structured PsS2 unit by the addition of a PS bridge. The P5S2 part of the molecule consists of two nearly regular five- (2) CI---C4 1.527 (9) $5--P4 2.113 (2) C5--C6 1.520 (9) P1--P2 2.203 (2) C5----C7 1.551 (8) P2--P3 2.217 (2) C5---C8 1.509 (9) P2--P5 2.180 (2) H32...S1 2.78 (7)* H63...$2 2.87 (7)* H42...P5 2.83 (7)* H72.--$2 2.75 (7)* H43...S!…”

Synthesis of trinorbornane

“…7 Probably the structurally most similar known compound is brexane 4 (tricyclo[4.3.0.0 3,7 ]nonane), which lacks only one interconnecting ethylene bridge compared to 1 and was synthesised by Nickon in 1964 in 9 steps ( Figure 2). 8 Later its synthesis has been improved by Brieger profiting from an intramolecular Diels-Alder reaction as the key step. 9 In similarity to 1, this tricyclic structure is also C 2 -symmetric but is composed of two superposed norbonyl units instead of three.…”