By triple epoxide ---3 cyclopropane transformation starting from cis-benzene trioxide the 3~~,6a,Sa-tris(TIPS-ethynyl) (lb), -tris(alkoxycarbonyl) (Id, e), -tricyano (If), and -tris(ammoniomethyl) ( l j ) derivatives of the still elusive parent cis-[ 1.1.11-tris-o-homobenzene (la) have been synthesized. Out of a number of carbon nucleophiles tested, a weakly basic mixed cyanocuprate of Li-TIPS-propyne proved the reagent of choice: Eliminations were largely avoided, the scyllo[*l-2,4,6-tris(TIPS-propargyl)cyclohexane-1,3,5-triol (13a), obtained in a stereoselective one-pot threefold epoxide opening (up to 69%), allowed the pertinent functional group manipulations. The selectivity of the base-induced triple cyclopropane ring closure in the flexible cyclohexane precursors strongly depends on the activating groups and is promoted by fixation of the "all-axial" conformation as an adamantoid orthophosphate. The AG# values determined for the generally neat 30 + 371 isomerizations [28.5 (le), 29.0 (If), 22.6 (11) kcal mol-l] are in line with concerted reaction courses ([o2s+o2s+o2s]). For the trinitrile If an X-ray structure analysis confirmed a nearly planar cyclohexane ring and a relatively large cyclohexane/cyclopropane interplanary angle (1 13").

An efficient asymmetric synthesis of the LTB 4 inhibitor Ontazolast is described. Commercially available (S)-r-pinene, which contains a 93.5% enantiomeric excess (ee) of the desired isomer, can be oxidized using phase-transfer conditions to the corresponding (R)-hydroxy ketone. Condensation of this keto alcohol with 2-(aminomethyl)pyridine provides an intermediate imine that can be alkylated with cyclohexylmethyl bromide or iodide. The alkylation proceeds with nearly complete transfer of chirality under mild conditions. Cleavage of the chiral auxiliary and isolation of the resulting (S)-pyridylamine by crystallization with L-tartaric acid furnishes the key amine building block in >99% ee and in excellent overall yield. The tartrate salt is then directly converted to the final product. The reaction sequence is described on a multigram scale.

The methylene (2, 7, 10) and spirocyclopropane derivatives (8, 11, 12) are made accessible from rac-trishomocubane(mono-, di-, tri-)ones and optically pure unsaturated and benzoannulated [2.1.1]-(19, 48), [2.2.1]-(30, 53), and D3-symmetrical [2.2.2]triblattanes (3, 4) from the enantiomers of these ketones by expeditious (one pot) ring enlargement and olefination procedures. In the case of the central [2.2.2]trienes (+)-3/( -)-3, novel members of the (CH),, family, optical resolution is advantageously postponed to the stage of the intermediate [2.2.2]triones (35, 41) and effected via their (R,R)-2,3-butanediol acetals. In the a-diketone series only the [2.l.l]dione (70) is , and [2.2.2]Triblattanes 2277Demjanov procedure via 15/16r'71 or even 93% using the Schollkopf sequence via 13/14"'] was achieved. Scheme 2. i) N2HCC02Et/n-butyllithium/THF/-78 to -3 0 T / 97%.ii) C3H5Pd(I)C1 dimer/CH2Clz/-78 to room temp./96%. -iii) NaHC03/H20/150"C/1 h/100%.iv) TMSCN/Zn12/CH2C12. -v) LiAIHdTHF.vi) NaN02/H20/glacial acetic acid/iv-vi: 81 YO

The He(1)-PE spectra of the parent [1.1.1]-, [2.1.1]-, [2.2.1]-, and [2.2.2]triblattanes 1-4, of their unsaturated or ketonic congeners 5-13 and benzo derivatives 14-20 have been recorded. For 1-4, the energy difference between the highest occupied orbitals (e" and a' mainly localized at the central bicyclo-12.2.2loctane unit) and the subsequent MOs increases with increasing number of ethano bridges. This observation is rationalized by using a first-order perturbation-theoretical approach.Orbitals of nonconjugated x-systems can interact with each other by a "through-space'' (OITS) and/or "through-bond'' mode (OITB)"]. The OITS mode is sometimes subdivided into the terms "homoconjugation"L21 and "spiroc~njugation"[~~. A prerequisite common to all of these OITS types is the spatially confined proximity and orientation of the nonconjugated x-fragment~[~I which can be achieved by their imbedding into a suitable o-system. In fact, record OITS values (2.2 eV) approaching that of classical R,T[ conjugation have been recorded for D2,,-bissecododecahedradiene~'~], in which the specific carbon skeleton enforces unu- 63

No abstract