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").
Das fur Synthesen in der ,,C-Reihe""] bewahrte transDioxa-tris-o-homobenzolcarboni tril 17 I2] ist, als Epimerengemisch, ein gut zugangliches Edukt fur Monoazaoctabisvalene 2. Es ist an C-9 acid genug, um ohne wesentliche Beeintrichtigung der Epoxidfunktionen deprotoniert und regioselektiv unter Dreiringbildung zu 18 cyclisiert zu werden (0.15 M Ansatze, 1 Aquiv. Bis(trimethylsily1)lithiumamid/THF, 0-20"C, 50-60Y0; Fp = 135-136"C, Jl,2 21 3.5, J l , , ~4 , J2,4 N 3.5, Jz.s N 3.5, J4,5 N 3.5 Hz). Bei der Umsetzung von 18 (50 mmol) mit Natriumazid/MgSO, (5 Aquiv., H,O, 40°C, ca. 5d) ist Substitution an C-4 keine Konkurrenz; in 90-95 Yo Gesamtausbeute erhllt man ein Gemisch der Azidodiole 19a (78%)/20a (7%) und dreier daraus entstandener (charakterisierter) Diazide (in toto 5 -10 YO), aus welchem sich durch Flashchromatographie die Hauptkomponenten verlustfrei abtrennen lassen. Die unter Der in Schema 1 skizzierte Syntheseweg basiert auf folgenden Befunden und Annahmen: 1) Das Edukt scyllo-Tnpropargyltriol 7 b (siehe Tdbelle 1) resultiert aus der dreifachen Epoxidoffnung
fused phenylcycloalkyl derivatives fused phenylcycloalkyl derivatives (rings with 3, 4, 7 or more members) Q 1040
-097Carbocyclic cis-(1.1.1)-Tris-σ-homobenzenes -Syntheses by Triple Epoxide → Cyclopropane Conversions, Structural Data, (. sigma.2s + σ2s + σ2s) Cycloreversions.-A weakly basic mixed cyanocuprate carbon nucleophile is the reagent of choice to open the triple epoxide (I) to fully substituted cyclohexane derivatives such as (II), which in several group manipulations can be transformed into cyclopropane derivatives such as (III). -(RUECKER, C.; MUELLER-BOETTICHER, H.; BRASCHWITZ, W.-D.; PRINZBACH, H.; REIFENSTAHL, U.; IRNGARTINGER, H.; Liebigs Ann./Recl. (1997) 5, 967-989; Inst. Org. Chem. Biochem., Albert-Ludwigs-Univ., D-79104 Freiburg/Br., Germany; EN)
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