The synthesis of [3.3.3]propellanes 18, 19, and 3 bearing one, dibenzo(phenanthro-[1,10]) [3.3.3]propellane 18 in an almost quantitative yield, irrespective of the stereoisomeric two, or three [1,10]-fused phenanthrene units instead of a simple benzene ring has been performed. Starting from composition of 7. In contrast, photocyclodehydrogenation of distilbene 9 gave the unusual propellane-fused elassovalene tryptindan-9-one 4, the hitherto unknown tryptindane-9,10dione 5 and tryptindane-9,10,11-trione 10, the corresponding 20 in a moderate yield, and the expected benzodi-(phenanthro-[1,10])[3.3.3]propellane 19 was only obtained in mono-, di-, and tribenzylidenetriptindanes 7, 9, and 13 have been prepared. In all three cases, the stereoisomers bearing a low yield. As an extreme case, tristilbene (Z,Z,Z)-13 eluded the desired threefold photolytic cyclodehydrogenation; cis-oriented benzylidene groups, i.e., (Z)-stilbene units, are formed predominantly. The monostilbene (Z)-7 and the however, catalytic cyclodehydrogenation by Pt/Al 2 O 3 /Ti at 310 Β°C furnished the threefold acephenanthrylene 3 in a tristilbene (Z,Z,Z)-13 were obtained in pure form and their stereochemistry was fully characterized. Photocyclo-yield of 18%. dehydrogenation of 7 under Mallory-Katz conditions gave
The most remarkable feature of [3.3.3]propellanes such as [a] FakultΓ€t fΓΌr Chemie, UniversitΓ€t Bielefeld With its fully unsaturated propellane wings including three UniversitΓ€tsstraΓe 25, D-33615 Bielefeld, Germany carbonyl functions, this propellane promised to be an ideal [b] Fachbereich Chemie und Chemietechnik, UniversitΓ€t-Gesamthochschule Paderborn, basis for the construction of more highly condensed deriva-Warburger Strasse 100, D-33098 Paderborn, Germany tives of 2, such as the tris-acephenanthrylene-type pro-