Synthesis of dodecahedrane precursors. 3. Synthesis of alkylidene-1,3-cyclopentanediones and attempts to roof peristylanes

Abstract

. Can. J. Chem. 62, 2612Chem. 62, (1984. Phenylsulfenylation of 2-alkyl-l,3-cyclopentanediones followed by oxidation and elimination is shown to give easy access to 2-alkylidene-l,3-cyclopentanediones, a heretofore rare class of highly reactive compounds with good synthetic potential as dienophiles, Michael acceptors, etc. The synthesis of 2-phenylthio-l,3-cyclopentanedione is given and its use as synthon for introduction of the 2-alkylidene-l,3-cyclopentadione group into~ther systems is described. The methodology is applied to the preparation of a substituted peristylane containing a complete complement of carbons, proper functionality, and correct stereochemistry for closure to a dodecahedrane. The X-ray structure analysis of an example of this ring system is given. Efforts to effect the closure are described.PHILIP E. EATON, WILLIAM H. BUNNELLE et PETER ENGLE. Can. J . Chern. 62, 2612Chern. 62, (1984.On dCmontre que la phCnylsulfCnylation des alkyl-2 cyclopentanediones-1,3, suivie d'une oxydation et d'une Clirnination, s'avkre une voie d'accks facile aux alkylidene-2 cyclopentanediones-1,3, une classe de cornposCs qui Ctait jusqu'a maintenant rare, qui sont trks rCadtifs et qui prCsentent beaucoup de potentiel en synthtse soit comme diknophiles, comrne accepteurs dans les reactions de Michael, etc. On rapporte la synthkse de la phknylthio-2 cyclopentanedione-1,3 et on l'utilise cornme synthon pour introduire le groupe alkylidtne-2 cyclopentanedione-l,3 dans d'autres systkmes. On a appliquC la mkthodologie pour prkparer un pinstylane substituk contenant un cornplCment cornplet de carbones, la fonctionalitk approprike et la bonne stirkochirnie pour effectuer une fermeture conduisant a un dodCcaCdrane. Faisant appel a la diffraction des rayons-X, on a dktermink la structure d'un cornposC faisant partie de ce systkme cyclique. On dCcrit les essais effectuCs en vue de rkaliser la fermeture dtsirke.[Traduit par le journal]

Reciprocal polyhedra and the Euler relationship: cage hydrocarbons, CnHn and closo-boranes [BxHx]2−

“…The requisite C 10 H 10 moiety, 44 , has been prepared (most elegantly via Paquette’s domino Diels–Alder route [ 26 ]) but all attempts at controlled dimerization (even on a transition metal template [ 27 ]) have so far proven fruitless. A second approach is based upon the five-fold symmetry of [5]peristylane, 46 ; this system has been accessed by Eaton ( Scheme 8 ) but attempts to add the 5-carbon roof, 45 , have not yet succeeded [ 28 ]. Another "3-fold" approach relies on the addition of a trimethylenemethane-like C 4 fragment, 47 , to C 16 -hexaquinacene, 48 ; but again complications arose during attempts to convert this molecule to 16 [ 29 ].…”