Functionalization of C6,, with Nitrile Oxides to 4,5-Dihydroisoxazoles and Their Structure DeterminationCycloadducts 3 of nitrile oxides 2 with c 6 0 (1) are synthesized and isolated. The cycloadducts are characterized by 13C-NMR spectroscopy and high-resolution FAB mass spectrometry. X-ray structure determination of the 3-(9-anthryl)-4,5-dihydroisoxazole derivative 3a of c 6 0 with CS2 included in the crystals is achieved at 173 K without disorder problems.

Radical‐Type Cyclization of Dienes, V. – Substrate‐Controlled Asymmetric Synthesis of (−)‐Hirsutene and (−)‐3‐Hydroxyhirsutene from (R)‐(−)‐Carvone (3aR,6aR)‐(−)‐6a‐Methyl‐3,3a,4,6a‐tetrahydro‐2H‐cyclopenta‐ [b]furan‐2‐one (6) and (1R,4S)‐(−)‐3‐[4‐(but‐3‐inyl)‐3‐methyl‐cyclopent‐2‐enyl]‐2,2‐dimethylpropan‐1‐ol (11) are key compounds in the synthesis reported in this paper. Enantiomerically pure 6 was obtained in five straightforward steps from the inexpensive precursor (R)‐(−)‐carvone (1). Compound 11 was prepared from 6 via an SN2′ reaction, by analogy with the synthesis reported by Curran et al. The linear triquinanes 13 and 15 were obtained in gram quantities in two additional steps. The utilisation of (S)‐(+)‐carvone (ent‐1) allows access to the other enantiomeric forms. X‐ray analysis of 15a confirmed the structure of 15 and, by correlation, that of 13.

cally:~'51 The E-isomer (with K=1.9, in CDC13) is favored.The keto ester 2c furnishes the Z/E mixture of the butatrienediester 5c. In contrast to 5b, 5c is configurationally stable at room temperature. Consequently, the isomers could be separated by conventional column chromatography. E-5c and 2-5c were obtained in 33% and 9% yield, respectively, in each case as pale yellow, crystalline and stable compounds (m.p. 87-88 "C and 71-73 "C, respectively). All the butatriene derivatives 5 prepared were characterized by accurate analytical and spectroscopic data.The esters 5 can be converted into the carboxylic acids 6-8. Since they have a pronounced tendency to undergo nucleophilic addition,l6I protic conditions had to be avoided. The hydrolysis was carried out with [ 18lcrown-6 as phase transfer catalyst of the THFIKOH system. 5a thus furnished the acid 6 in 83% yield as an orange-yellow crystalline substance. Eand 2-5c yielded the isomerically pure dicarboxylic acids Eand 2-8, respectively, in 65% yield as bright-yellow crystals. In contrast, E-5b forms a Z/E mixture of the dicarboxylic acids 7, from which isomerically pure, orange-colored E-7 precipitates in 7 1% yield upon crystallization. 2-7, on the other hand, could-due to sparing solubility-only be obtained by a very tedious chromatographic separation.Upon determination of the melting points, still in the crystalline state, 2-7 and Z-8 rearranged into the E-isomers.The dicarboxylic acids Eand 2-7, like their esters 5b, have different 'H-NMR spectra;['61 the equilibrium constant K , with a value of 2.9 (in [DJDMSO) in favor of the E isomer, is significantly higher than in the case of 5b.

A series of ten inverse calix[n]arenes (2-11) bearing four to thirteen benzene units were prepared by starting from 3,4,5-trimethoxybenzaldehyde followed by LC separation on silica gel. In 2-11 the substitution pattern is interchanged compared with the usual calixarenes. The conformational analysis was undertaken by variable temperature 'H-NMR spectroscopy and by MM2 calculations. Calix[4]arene 2 is a rigid molecule and shows the 1,3-alternate conformation which in addition was proven by X-ray analysis. At low temperatures the calix[5]arene 3 adopts the uudod conformation, where a methyl group of one benzene unit residues in the cavity of the macrocycle. At low temperature calix[6]arene 4 forms a n 1 :2 equilibrium between the 1,3,5-alternate (ududud; 4E) and the uududu (4B) conformation. Conformation 4B can be regarded as a n intramolecular combination of a cone and an alternate arrangement of the benzene units. The calix[8]-arene shows the highest AG* value of the series and adopts an uuududdd conformation at low temperature. The inverse calixarenes 5 and 7-11 bearing seven and nine to thirteen aromatic units, respectively, are conformationally highly flexible systems even at low temperatures.The name calixarenes (Greek: calix = vase), originally introduced by Gutsche ['], describes polycyclic metacyclophanes, where alkyl phenols are connected by methylene bridges (A). In these structures the free OH groups are oriented in the same direction representing the ground of the vase while the alkyl residues from the rim. Compounds, in which these substituents are interchanged, are called inverse calixarenes (B) by us. The alteration of the substituents should change the general properties such as the chemical reactivity, complex formation and conformational behavior, because the most important property, i.e. the hydrogen bonding is less pronounced or not possible. The basic compound B has not yet been synthesized but, surprisingly, we were able to synthesize persubstituted derivatives of B starting from 3,4,5-trimethoxytoluene 1. Synthesis of 3-11Compound 1 available by catalytic hydrogenation of 3,4,5-trimethoxybenzaldehyde, reacts with paraformaldehyde in strong acidic solution. The composition and concentration of the reaction products strongly depends on the reaction conditions, in particular on the acid concentration. In the solvent combination THF/H2S04 10: 1.7 a tough oil is produced, which does not show aromatic proton signals in the NMR spectrum. From this oil the compounds 3-11 were isolated by chromatographic separation on silica gel followed by a recycling MPLC. 3-11 are colorless crystalline compounds with m.p. >29OoC. The compounds with aromatic rings >6 if crystallized are quite insoluble in common organic solvents. Therefore, all NMR investigations of these compounds were performed with a material not yet recrystallized. In fact, such adducts are observed in the laser desorption mass spectra of the high-molecular weight compounds 7-11.

Ausgehend von dem aus Catalpol hergestellten (lS,6R,7R,9R)-( + )-7,9-Bis(p-phenylbenzoyloxy)- 3-oxabicyclo[4.3.O]nonan-2-ol (1) werden (15R)-und (15S)-15-Methyl-12-epi-PGF20 [(15R)-5bund 5b] kristallin und enantiomerenrein synthetisiert. Im Gegensatz zu der von uns beschriebenen Synthese von 12-epi-PGFzg sind durch die Einfuhrung der p-Phenylbenzoyl-Schutzgruppen auch die Zwischenprodukte 2-5 a kristallin, so daI3 ihre physikalischen Konstanten eindeutig bestimmt werden konnten. Die Rontgenstrukturanalyse von (15R)-1 S-Methyl-12-epi-PGF2B beweist, daR die von uns aus den analytischen und spektroskopischen Untersuchungen gemachten Aussagen richtig sind. Chemistry and Stereochemistry of Iridoids, IVI). -Synthesis and X-Ray Structure Analysis of 15-Methyl-12-epi-prostaglandin FIBCrystalline (15R)-and (15S)-15-methyl-12-epi-PGF2B [(15R)-5b and 5b] are synthesized enantiomerically pure starting from (1S,6R,7R,9R)-(+)-7,9-bis@-phenylbenzoyloxy)-3-oxabicyclo-[4.3.01nonan-2-01 (1). which is prepared from catalpol. Contrary to our described synthesis of 12-epi-PGF2B, the intermediate products 2-5 a are crystalline by virtue of the introduction of the p-phenylbenzoyl protecting group. Thus, their physical constants could be determined unequivocally. The X-ray structure analysis of (15R)-15-methyl-12-epi-PGFzg proves the correctness of our earlier statements based on analytical and spectroscopical investigations.Vor kurzem haben wir eine allgemeine Synthese fur 12-epi-Prostaglandine aus Catalpol beschrieben ". Da die Zwischenprodukte als Ole anfielen und manche wegen der Tetrahydropyranyl-Schutzgruppe als Diastereomerengemische vorlagen, war ihr spektroskopischer Konstitutionsbeweis nicht eindeutig mdglich. Nur die kristallinen Endprodukte bzw. ihre Derivate konnten spektroskopisch untersucht werden. Durch die Einfuhrung der p-Phenylbenzoyl-Schutzgruppe gelang es, nun auch die Zwischenprodukte 2 -5a kristallin zu erhalten und dadurch ihre Konstitution und Konfiguration analytisch und spektroskopisch zu beweisen. Diese Ergebnisse werden durch die