SynthesLp and Reactions of Tricyclo[9.3.0.04*8~tetradeca-4,7,11,14-tetraene Carsten Mink and Klaus Hafner* hstitut Air Drgankhe Chcanie der Tedmiha Hochachule Darmtait, MemnsW3e 22, D-64287 Dmmtadt (Gemaay) Ah-'hetitlecmpouad6hrrsbeensynthesiEedby cmdematioo of 1,2-bis(trimethylsilylcyclopeatadienyl)e (3) witi glyoxal sulfate to the tricyclic aysbm 4 d follow@ t-edu&m m well m dedylatiot~ Twofold deqmtonation of 6 yields the dilithim cumpoud 7, which waa trmsfommzd into the pmtatidvenophme~ 8 and 9. Derivatives of the title compound like 1 proved to be useful intetmediates for the synthesis of the dicyclopenta[a.e]cyclooctene system 2 with a delocaked 14x-electron system, which exhibits intemsting physical and chemical propertie~.~ Furthermore, they should open an access to so far unknown pentafulvenes with two ethano-bridges as well as [2][2]metallocenophanes; these are bent metallocenes containing two cyclopentadienyl ligands in a non-parallel geometry and therefore deserve increasing interest as pmcursors for efficient catalysts for the stereoselective polymerization of alkenes. 2 We report herein a first synthesis of tricyclo[9.3.0.04-81tet&eca-4,7,11,14-tetraene (613 from 1,2bis(trimethylsilylcyclopentadienyl)ethane (3) ,4n5 which is obtained in 67% yield as a mixtum of tautomers by reaction of the dilitbium salt of the easily available 1,2-bis(cyclopentadienyl)ethane6 and trimethylsilyl chl~ride.~ Deprotonation of 3 with 2 equiv. n-BuLi and cyclizing condensation with glyoxal sulfate yields the 2.7-bis(trimethylsily1)-4,5dihydrodicyclopenta[a,elcyclooctene (4)8 (dark red violet crystals, mp 130ยฐC; yield 4%). 4 is reduced with LiAlH4 to a mixture of anti-and syn-6.13-bis(trimethylsilyl)-tricyclo[9.3.O.O4*8Mradeca-4,7,ll,l4-tetraene (5a.b). which can be separated by chromatography on Al203 with n-pentane (509: colorless cry&&, mp 87ยฐC 65%: 5b1ยฐ: colorless crystals, mp 81T. 22%). Desiiylation of 5 with tetra-n-butylammonium fluoride leads with 65% yield to the hydmcarbon 6. isolated as colorless. below room temperature melting and even at -50ยฐC rather unstable crystals. 'H, 13C NMR and UV spectral 1 are in accordance with the pqosed struchm of 6. The 2-fold deprotonation of 6 with 6Li-emiched LiTMP in [D81THF fkrnishes the dilithium salt 7. which was studied by