Horst Neudeck

Optisch aktive, aromatische Spirane, 8. Mitt.: Darstellung optisch aktiver, 5, 5′, 6′-trisubstituierter 2,2′-Spirobiindane bekannter Chiralität und enantiomerer Reinheit

Starting from (+) (2R) methyl 5′-ethyl-2,2′-spirobiindane-5-carboxylate of known enantiomeric purity 79 optically active, configurationally correlated 5,5′,6′-trisubstituted 2,2′-spirobiindanes (2–7) were prepared for the purpose of testing a “shortened polynomal Ansatz” for chirality functions. Their optical rotations and1H-nmr spectra are reported.In this context several 6-substituted 5-ethylindanes (1) were prepared as model compounds for synthetic transformations.

Optisch aktive, aromatische Spirane, 9. Mitt.: Überprüfung eines Näherungsansatzes für Chiralitätsfunktionen bei 5,5′,6′-trisubstituierten 2,2′-Spirobiindanen

In order to test the semiempirical value of chirality functions in their mathematically most simple form 23 new optically active 5,5′-disubstituted 2,2′-spirobiindanes1 of known chirality and enantiomeric purity were prepared. Thus a set of about hundred compounds is now available with altogether sixteen types of ligands (i.e. substituents including hydrogen); the experimental molar rotation of fifteen compounds is used to determine the value of a ligandspecific parameter occuring in the used chirality polynomial. According to theory this polynomial is an approximation for the total rotation of derivatives with ligands of three different types and it approximates an experimentally separable part of the rotation as far as compounds with four different ligands are concerned.The additional chirality component, occurring exclusively in the case of derivatives with four different types of ligands turns out to be relatively small but not vanishing. Accordingly, the molar rotation predicted by our method is very good for disubstituted spirobiindanes of type1 and rather good for others with three different types of ligands but is distinctly worse for those with four different ligands. The numerical trend, however, is clearly represented even in cases where our calculation in principle refers to a part of the phenomenon only and the predicted absolute configuration is in call cases in agreement with the experiment.An adequate criterion to judge the quality of our approximation is introduced.

Stereochemie von α,ω-Diphenyl-alkan-α,ω-diolen

Reduction (both catalytically and with complex hydrides) of the diphenyl diketones1 (a, b, c andd withn=0, 2, 3 and 4) was investigated mainly with regard to the diastereomeric ratio of the diols2. For2 a and2 b exact results were obtained by NMR spectroscopy (without or with shift reagents) of the diol mixture (2 a) or after stereoselective cyclization to the cyclic ethers (3 b). AlsoGC andLLC were employed for the analysis of2 a (GC of the trimethylsilyl derivatives) and for the ethers3, resp. (GC for3 a and3 d;LLC for3 b and3 c).The reduction of1 a, 1 b (and in part1 c) proceeds with high stereoselectivity; themeso-diol preponderates in the case of2 a, therac.-diol for2 b and2 c; with increasingn the diastereomeric ratio approaches the statistical ratio of 1∶1.Preparations of the stereoisomeric diols (2 b, c andd via acetylenic precursors) and of the cyclic diphenyl ethers (by stereoselective cyclization and/or chromatographic separation;3 c and3 d for the first time) as well as the determination of their configurations are described. The latter was achieved by NMR and for the ethers3 also by hydrogenation of the corresponding heteroaromatics.

AROMATISCHE SPIRANE, 23. MITT. : DARSTELLUNG VON UNSYMMETRISCH SUBSTITUIERTEN DIMETHYL-2,2'-SPIROBIINDAN-1,1'-DIONEN

SummaryBoth spirodiketones7 and8 were obtained as a mixture (56:44) by treatment of dicarbonic acid5 with polyphosphoric acid (PPA).5 was accessible from dimethylester3, synthesized byretro-Claisen reaction between1 and2. In the same way,30 was obtainedvia27. The preparation of the pure spiro compounds7 and8, resp., was achieved by aldol reaction between9 and10 or9 and16, resp. Short treatment of the resulting compounds11 and17 with diazomethane yielded the methylbenzoates12 and18. Prolonged reaction (several hours) gave the pyrazole compounds14 and19, resp., which were also obtained (several days) from phthalides14 and20. The latter were formed from the benzylidene compounds11 and17, resp., by heating.11 and17 (after hydrogenation to15a and21a) were cyclized either withPPA or thermically to the spiro compounds7 and8. The main product20 was cyclized thermically to8 after reduction with zinc to a mixture of21a and8 (20:75).

Aromatische Spirane, 14. Mitt. Darstellung von 2,2′-Spirobi-(s-hydrindacen) und seinen Vorstufen

AbstractThe title compound35 was prepared by catalytic reduction of the diones29 a and11a.29 a was synthesized by systematic anellation of fivemembered rings to the positions 5,6 and 5′,6′, resp., of 2,2′-spirobiindane. The preparation of11 a was achieved byFriedel-Crafts cyclisation of bis-(5-indanylmethyl)-malonic acid. s-Hydrindacene-1-one5 a was prepared as a precursor for the synthesis of11 a (see forthcoming publication) and its derivates as models for corresponding anellation and substitution reactions.

Optisch aktive, aromatische Spirane, 11. Mitt.: Synthese optisch aktiver mono- bis heptasubstituierter 5-Methyl- und 5-Ethyl-2,2′-spirobiindane und analoger Naphthalinderivate bekannter Chiralität und enantiomerer Reinheit

Starting from optically active 5,5′-dimethyl, diethyl, and 5-ethyl-5′-methyl-2,2′-spirobiindane as well as from 5′-ethyl-spirobiindane-5-carboxylic ester of known enantiomeric purity and configuration 75 mono to polysubstituted 2,2′-spirobiindanes have been prepared. Amongst these are several compounds with rings anellated in the 6,7 (and 6′, 7′) positions, especially a spirohydrocarbon4 x with orthogonal naphthalene units the circular dichroism of which is reported and discussed.Several mono and disubstituted 5-methyl and ethylindanes (1,2) have been prepared as models for synthetic transformations in the spirobiindane series.From the molar rotations of symmetrically diacylated 5,5′-dimethyl and diethyl spirobiindanes (4a, 7b, 7c) empirical ligand parameters λ for acetyl and methoxycarbonyl were determined which gave much better results in the calculation of the rotations of appropriate spirobiindanes (with the “shortened polynomal Ansatz”) than the λ-values deduced previously from 5,5′-disubstituted spirobiindanes. The significance of these results is briefly discussed.

Zur Anwendung des Näherungsansatzes für Chiralitätsfunktionen an trisubstituierten 2,2′-Spirobiindanen

From13C-NMR results, modified ligand parameters (λ-values) for theo-acetyl group in trisubstituted 2,2′-Spirobiindanes have been derived. With theses values a much better agreement between calculated and measured optical rotation is obtained.

Optisch aktive aromatische Spirane, 13. Mitt.

Several optically active title compounds were obtained from the 4′-acetyl-4-carboxylic acid2 or the 4,4′-diacetyl derivative4. (−)-2 was accessible by optical resolutionvia its (−)-α-phenethylamine salts, (+)- and (−)-4 as well as the enantiomeric methylesters3 (of2) were obtained by chromatography on triacetylcellulose in ethanol. The enantiomeric purities were established either from the chromatographic results or from the1H-NMR spectra of the phenethyl-amine saltes (via the diastereotopic acetyl protons).The chirality (−)-(2R) was deduced for all new compounds from a chemical correlation between (−)-2 and (−)-4 and on the basis of the CD spectra of the latter and of (−)-(2R)-17 of known absolute configuration.From the molar rotations of these 4,4′-disubstituted 2,2′-spirobiindanes (empirical) ligand parameters λ were determined which for some cases gave good results in the calculation of the rotations (using the “shortened Ansatz”). These results are briefly discussed especially in comparison with 5,5′-disubstituted 2,2′-spirobiindanes.

Aromatische Spirane. 15. Mitt. Darstellung von 2,2′-Spirobi-(s-hydrindacen)-1,1′-dion und von 4,4′-disubstituierten 2,2′-Spirobi-(s-hydrindacenen)

The title compound6 a was prepared by cyclisation of the diacid4 b. The diester4 a of4 b was synthesized by alkylation of2 with3 and following Retro-Claisen-reaction. After catalytic reduction of6 a to8 a two identical substituents were introduced byFriedel-Crafts-reaction (28). By transformation of the acetylgroups several other derivates (29–36) could be obtained. The unsymmetrical compounds (e.g.21) were prepared from20, whose precurser was the spiroketon10 a.

Lanthanide induced shifts of sterically hindered aromatic carbonyl compounds oxomethylene-bridged, acetyl-, and formyl-2,2′-spirobiindanes

The lanthanide induced shift (LIS) data of 10 polysubstituted 2,2′-spirobiindanes with a carbonyl group in conjugation to an aromatic ring were simulated using theMcConnell-Robertson equation. In the case of oxomethylene-bridged derivates (with CO incorporated in a more or less rigid ring) the classical one site or two site models gave reasonable results. For sterically hindered acetyl or formyl derivates (bothortho positions alkyl-substituted) a new model was developed: the carbonyl group was found to be 30° out of the aromatic plane and the possible 4 positions (±30° and ±150°) turned out to be populated differently depending on theortho substituents. The LIS programme had to be modified to account for this situation.ZusammenfassungEs wurden die Lanthaniden-induzierten Verschiebungen (LIS) von 10 polysubstituierten 2,2′-Spirobiindanen mit einer Carbonylgruppe in Konjugation zu einem aromatischen Ring mittels derMcConnell-Robertson-Gleichung rechnerisch simuliert. Im Fall von Oxomethylen-überbrückten Derivaten (mit CO in einem mehr oder weniger starren Ring inkorporiert) ergaben sowohl das übliche „One Site” — als auch das „Two Site”-Modell gute Resultate. Im Fall sterisch gehinderter Acetyl- oder Formylderivate (beideortho-Positionen alkyl-substituiert) mußte ein neues Rechenmodell erstellt werden: die Carbonylgruppe erwies sich als etwa 30° aus der Benzolebene herausgedreht und die 4 möglichen Lagen (±30° und ±150°) zeigten dabei verschiedene Populationen. Das LIS-Programm mußte entsprechend modifiziert werden, um die Komplexierungsverhältnisse wiederzugeben.