Dicyclopentyl ketone

The first systematic approaches to cis,syn,cis stereoisomers of this ring system were recently described by Eaton and co-workers.328) To gain access to monoketone 320 (Scheme 49), dicyclopentyl ketone was directly brominated and dehydro-brominated. The resulting cross-conjugated ketone 318 underwent acid catalyzed cyclization to provide the first tricyclic intermediate (319). Catalytic hydrogenation of 319 led stereospecifically to 320. Its six 13C resonance lines require that the molecule have C2 or Cs symmetry. The stereochemistry of this product was ulti-... 

If the carbonylation is conducted in the presence of a small amount of water, migration of the third alkyl group is inhibited. Oxidation of the hydrate produced then gives the ketone (5.30). Yields obtained are generally high, and the sequence provides a convenient synthetic route to ketones. For example, cyclopentene was converted into dicyclopentyl ketone in 90% yield. 

Sym. ketones. A soln. of cyclopentene in diglyme allowed to react with a soln. of borane in tetrahydrofuran, stirred 1 hr. at room temp., tetrahydrofuran removed by distillation under reduced pressure, water added, heated to 100°, flushed with GO, stirred, after 2.5 hrs. when GO-absorption has ceased ice-cooled and oxidized below 35° with HgOg/NaOH dicyclopentyl ketone. Y 90%. 

Die rohen Azine des Cyclobutanons und Cyclopentanons konnen liber Platin(IV)-oxid in Essigsaure bei 2,8 bar mit Ausbeuten von 45 (1,2-Dicyclobutyl-hydrazin) bzw. 77% (1,2-Dicyclopentyl-hydrazin, bez. auf Keton) hydriert werden5 (das Cyclobutanon-azin muB zuvor isoliert werden). Auf analoge Weise (2071,5-2 bar) sind 1,2-Dicydooctyl-und 1,2-Dicyclododecyl- (jeweils 73% d.Th.)6 sowie (60—7072,5 bar) l,2-Bis-[diphe-nylmethyl]-hydrazin (36% d.Th.)7 zuganglich. 

Dicyclomine hydrochloride Dicyclopentadiene Dicyclopentyl ether Dicyclopropyl ketone... 

Rearrangements of pinacol, l,l -dihydroxy-l,l -dicyclopentyl, and 1,1 -dihydroxy-1,1 -dicyclohexyl to the corresponding ketones, with negligible alkene formation, occurred in superheated D2O in 60 min at 275 °C [103]. Although a classical method for the pinacolone from pinacol required boiling in 25%... 

---