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Abstract. Cationic cyclization of 2-[6-(3-methoxyphenyl)-(Z)-3-hexenyl]-3-methyl-2-cyclopenteno1 (7a) produced 1-and 3-methoxy-l7-methyl-8a-gona-l,3,5( lo), 13( 17)-tetraene (8a and 9a) with complete stereospecificity. Cyclization of similar substrates with an alkyl substituent in the appropriate position gave exclusively 1 la-alkyl derivatives of 8a and 9a. The products were converted into the corresponding 13a, 17a-epoxides by peracid oxidation and hence into derivatives of 8a-estrone and 8a-estradiol. 1 la-Methyl-8a-estra-l,3,5(lO)-triene-3,17~-diol (16b) was obtained in its two enantiomeric forms via resolution of its 3-methyl ether.

Recueil des Travaux Chimiques des Pays-Bas, 10412. february 1985 59 further two times. The material thus obtained was dissolved in water (15 ml) and washed with diethyl ether (3 x 15 ml). The water layer was partly evaporated in vacuo (30°C) and thereafter lyophilized. 63 mg (89%) of a slightly yellow coloured fluffy material was obtained.TLC (cellulose F,,, , DC-Alufolien, Merck; solvent VI): major compound R, 0.72 (Ninh.+). Several minor compounds were detected. 7 was used without further purification. H-Ala-Ser(PGal)-Ala-OH (8)Hydrazine hydrate (97 ~1 , 2 . 0 mmol) was added to a stirred solution of 7 (58 mg, 0.1 mmol) in CH,OH (1.0 ml) at room temperature.After 40 min, the solution was cooled to O'C, 2,4-pentanedion (205 pl, 2.0 mmol) was added and stirring was continued at room temperature for 15 min. The solution was diluted with water (25 ml) and washed with CHCI, (3 x 10 ml). The water layer was partly vaporated in vacuo and thereafter lyophilized. The material thus obtained was purified by chromatography on a 60 x 1.5 cm column of Sephadex G-10 (Pharmacia). Elution was effected using water at a flow rate of 20 ml/h. Fractions of 5 ml were collected. Aliquots of each fraction were spotted on TLC plates. Spots were visualized with ninhydrine reagent and methanolic H,SO,. 8 (37.2 mg, 91 %) was obtained by lyophilization of fraction 8-12. Using 300 MHz 'H NMR, the purity was estimated to be over 97% ( a small quantity of aromatic material together with some uncompletely deacetylated glycopeptide were present). A sample of8 was purified by chromatography on a 20 x 0.3 cm CP-TM-Spher CIB HPLC column (Chrompack). Elution was effected using water at a flow rate of 0.5 ml/min. The eluate containing unretarded material (UV detection at 205 nm) was collected and lyophilized. TLC (Cellulmose F2',, DC-Alufolien, Merck): IV, R, 0.23; V, 0.12; VI, 0.21 (Ninh'). 100 MHz 13C NMR (D,O, pH 5.48 meter reading): F 105.4 (d, Gal C'); 63.7 (t, Gal C6); 71.0 (t, Ser Ca); 182.2, 173.6, 172.4 (3 x s, C = 0); 78.0, 75.3, 73.3, 71.3 (4 x. d, Gal carbons, probably C', C3, C2 and C', r e~p e c t i v e l y~~-~~) ; 56.4,53.8,51.7 (3 x d, amino acid C);

Die durch entsprechende Wittig‐Reaktionen der Aldehyde (IV) stereospezifisch in der Z‐Konfiguration (mit nur 6‐15% der E‐Isomeren als Verunreinigung) erhältlichen Hept‐4‐enyl‐furane (V) lagern sich unter milden Bedingungen unter Beibehaltung der Z‐Konfiguration über die Dione (VI) in die Arylhexenyl‐cyclopentenone (VII) um, die zu den Alkoholen (VIII) reduziert werden Diese lassen sich bereits mit Ameisensäure oder ZnCl2 stereospezifisch zu den tetracyclischen Tetraenen (IX) bzw. (X) cyclisieren (die Cyclisierung sowohl der Z‐ als auch der E‐Olefine erfolgt auf dem energetisch bevorzugten Weg über die Sessel‐Konformation zu cis‐syn‐konfigurierten Tetracyclen).

In Anlehnung an Literaturverfahren wird das Cyclopentenol (VII) dargestellt, das mit BF; ‐ Et2O in das 1‐Methoxynonaretraen (VIII), zusammen mit dem 3‐Methoxyisomer (IX) übergeführt wird.