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A bisdehydro[14]annuleno[c]furan and a tetrakisdehydro[14]annuleno[14]annulene have been synthesized; their properties and effects of annelation on annulene rings are discussed on the basis of 1H NMR and electronic spectra. Attempts to synthesize the related [14]annuleno[16]annuleno[14]annulene are also described.

It has been found that the longest-wavelength of the absorption maxima (λ L ) in the electronic spectra of both the α,ω-diarylpoly-yne and polyene series varies linearly with the x th power of the number (n) of multiple bonds [λ L ∝ n x , the value of x changes with both the structure of the terminal groups and the position of substitution of the unsaturated chain, e.g. x = 2 for α,ω-Di-1-and 9-anthrylpoly-ynes( 1 n ,and 2 m n = 1–6)]. The results are different from the formerly accepted regularity (λ L 2 ∝ n ). The paper describes the fluorescence spectra characteristics of a series of 1 n and 2 n . The results of this investigation shows that, as in the case of the absorption spectra, both the excitation maxima ( λ ex ) and the emission maxima (λ em )in the fluorescence spectra of 1 n and 2 n have a linear relationship with n 2 (λ ex ∝ n 2 and λ em ∝ n 2 , respectively).

Our recent studies seem to indicate that annulenoannulenes consisting of two same size nuclei should be fused systems of two diatropic moieties. In order to obtain further information on the nature of annulenoannulene, the synthesis of dibenzo- and benzotrisdehydro[14]annuleno[14]annulenes has been performed.

Isorenieratene has been efficiently synthesized using 4-( t -butylthio)-3-buten-2-one as chain lengthening agent.

An improved synthesis of tetra-t-butylhexakisdehydro[18]annuleno[26]annulenedione, a key compound for the synthesis of the tricyclic annulenoannulenoannulene, was carried out. Two dideuterio derivatives of the [18]annuleno[26]annulenedione has been synthesized. An attempted synthesis of tetra-t-butyloctakisdehydro[18]annuleno[18]annuleno[18]annulene is described.

Two position isomers of di-t-butyl-diphenyl-1,8-bisdehydro[14]annulene corresponding to o- and m-isomers of terphenyl have been prepared by a stepwise reaction sequence, and their physical properties were compared with those of 3,10-di-t-butyl-7,14-diphenyl-1,8-bisdehydro[14]annulene which corresponds to the p-isomer of terphenyl. The marked difference in electronic spectra between o-, m-, and p-isomers of terphenyl could not be observed in the spectra of “ortho”-, “meta”-, and “para”-isomers of the [14]annulene. Dimethoxy derivative of the “para-isomer, 3,10-di-t-bufyl-6,13-dimethoxy-7,14-diphenyl-1,8-bisdehydro[14]annulene, has been synthesized.

The synthesis designed to lead to isomeric di-tert-butyldiphenyl-tetrakisdehydro[18]annulenes (VII and XIII) have been performed. It was found that the isomeric tetrakisdehydro[18]annulenes (VII and XIII) are identical in all respects, thus providing chemical evidence for the identity of diacetylene and hexapentaene units incorporated in the aromatic 18π-electron system. Argon laster Raman spectra of VII and XIII exhibited single absorption due to stretching vibration of sp-hybridized carbon-carbon bond at 2080 cm−1 indicating equalized nature of acetylenic and cumulenic linkages in the aromatic dehydroannulene system.

Tetrakisdehydro[18]annuleno[20]annulene has been synthesized. The 1 H NMR spectra clearly indicate the induction of dia- and paramagnetic ring currents in 18- and 20-rings, respectively. A marked suppression of the diatropicity in the 18π moiety was observed being in the same trend in other tetrakisdehydro[4n]annuleno[4n′+2]annulenes. The 1 H NMR spectroscopic behavior of the annulenoannulenes is consistent with theoretical conclusion.

The synthesis of tetrasubstituted tetradehydro[18]− and [22]annulenes containing a diacetylene and a hexapentaene unit has been accomplished by reductive dehydroxylation of corresponding 18-membered and 22-membered cyclic glycols. On the basis of these studies, a general method of preparation of tetrasubstituted didehydro[4n + 2]annulenes containing an acetylene and a butatriene unit has been developed. The didehydro[4n + 2]annulenes (n = 3 ~ 7) were found to be diatropic and to have high conformational stability. The n.m.r. spectral properties of the didehydroannulenes have been discussed. The synthesis of didehydro[14]annulenes annelated with naphthalene or benzene has been achieved, and the effect of annelation on π-electron delocalization of the annulene ring has been discussed.

Chemical and Electrochemical reductions of bisdehydro[14]- and [18]annu1ened1ones clearly revealed their quinonoid nature.

Tetrakisdehydro[14]annuleno[16]annulene consisting of an aromatic bisdehydro[14]-annulene and an antiaromatic trisdehydro[16]annulene has been synthesized. The 1 H NMR parameters clearly indicate the strong paratropicity and diatropicity of the 16-membered and 14-membered rings, respectively.

(+)- endo - cis -Bicyclo[3.3.0]oct-7-en-2-ol gave good optical yields in the kinetic resolution of aryl- t -butylacetic anhydrice, establishing the absolute configuration of t -butyl-α-naphthylacetic acid as ( S ) - (+).

Three optically active diastereomers of 3,8-di- t -butylspiro[4.4]nonane-1,6-dione have been prepared. Their c.d. spectra showed very different features to each other in spite of the same configuration at their spiro centers, showing the sensitivity of c.d. to minute changes in the orientation of chromophores.

Syntheses of dimethyldiphenyl-(VI and XII) and tetraphenyltetrakisdehydro[18]annulenes (XVII) have been performed. It was found that the reaction sequence used for the synthesis of tetramethyltetrakisdehydro[18]annulene can be used generally for the preparation of tetrakisdehydro[18]annulenes having various substituents. The annulenes (VI, XII, and XVII) were found to be strongly diatropic having high conformational stability. Remarkable stability is provided by introduction of phenyl groups accompanied with decrease in solubility of the annulene. Dimethyldiphenyl derivative was prepared by two different routes which will lead to isomers (VI and XII) with respect to the relative positions of the diacetylene and hexapentaene linkages to the substituent groups. The isomers (VI and XII) can be regarded as presumably identical, but precise agreement of NMR and UV spectra could not be attained. Bathochromic shift of UV spectra of phenyl substituted annulenes compared with tetramethyl analogue indicated that ph...

Synthesis of naphtho-tri- t -butyltrisdehydro[16]annulene containing a hexapentaene and an acetylene units has been described. It was found that the [16]annulene is less stable and the paratropicity is much stronger as compared with previously reported isomeric naphtho[16]-annulene containing a diacetylene and a butatriene linkage.

Synthesis of a naphtho-tri-t-butyltrisdehydro[16]annulene has been described. Suppression of paratropicity of the 16-membered ring was observed. Comparison of 1H NMR spectrum of the [16]annulene with that of naphtho-tri-t-butylbisdehydro[14]annulene suggests that the trans double bond adjacent to naphthalene in the [16]annulene is twisted out of the mean molecular plane.

The electronic absorption spectrum of diphenylhexatriyne has been divided into two components polarized along the long and the short molecular axes by means of dichroism analysis using the stretched-polymer-film technique; i.e., a reduced polarization spectrum has been obtained. This reduced polarization spectrum can be explained by a modified PPP calculation including the interaction between mutually perpendicular π and π′ systems in the conjugated system. It has been clarified that the relative intensities of the first and second bands of diphenylhexatriyne reflect the magnitude of interaction between mutually perpendicular π and π′ systems, which is quite great. The magnitude of the electron-repulsion integral between π and π′ electrons is estimated to be about 20–30 per cent of that between ordinary π (or π′) electrons.

Treatment of substituted octa-2,6-dien-4-yne-1,8-dial derivatives with CF3COOH gave cyclopentadiene, thiophene, or isobenzothiophene derivatives. Formation of an 18-membered cyclic ether was observed in the case of octa-2,7-dien-4-yne-1,6-diol derivative.

The cyclic dimerization of 1,7-disubstituted-1-oxo-2,4,6-nonatrien-8-ynes on treatment with a suspension of potassium hydroxide in liquid ammonia to give tetrasubstituted 18-membered cyclic glycols has been achieved. The cyclic glycols could be converted into 3,9,12,18-tetrasubstituted 1,10-bisdehydro[18]annulenes which were found to be conformationally stable and strongly diatropic.

1,6,12,17-Tetraphenyl-2,4,13,15-tetrakisdehydro[22]annulene has been synthesized. The sparlingly soluble tetrakisdehydro[22]annulene was found to be conformationally stable and strongly diatropic.

Two position isomers of di-t-butyl-diphenyldidehydro[14]annulene have been prepared according to a stepwise sequence of reactions and their physical properties were compared with those of another position isomer, 3,10-di-t-butyl-7,14-diphenyl-1,8-didehydro[14]annulene. The synthesis of 3, 10-di-t-butyl-6,13-dimethoxy-7,14-diphenyl-1,8-didehydro[14]annulene has been performed. The introduction of methoxy groups causes a hypsochromic shift with hypochromism and a bathochromic shift with strong hyperchromism of medium and longest wavelength bands of the electronic spectrum, respectively.

A homologous series of [4n+2] annulenes reduced with alkali metals yields paratropic (4n)π-dianions. 1H NMR chemical shifts are most significant for a description of the relevant π-electron structures. However, the shift data turn out to reflect sensitively the ion-pairing. Therefore, the experimental conditions (counterion, solvent, temperature, organic ion) have been varied systematically, and a consistent description of the existing contact-solvent-separated ion pair equilibria (e.g. as a function of ring size, π-charge distribution etc) has been obtained. The interdependence of ion-pairing and ring current effects is discussed.

Increase of diatropicity of the dibenzotrisdehydro[14]annuleno[14]annulene as compared with that of benzotrisdehydro[14]annuleno[14]annulene, which is expected if the dibenzannulenoannulene is a peripheral conjugated system could not be observed. The observed NMR behavior seems to indicate that the dibenzo derivative is a fused system consisting of two 14π-electron systems.

A convenient synthesis of α,β- and α,β,γ,δ-unsaturated aldehydes using readily accessible 4-( t -butylthio)-3-buten-2-one as synthon was described.

2,3 : 6,7-Dibenzobicyclo[3.3.1]nona-2,6-diene-4,8-diol was synthesized and resolved via (−)-menthoxyacetate. Several kinds of optically active derivatives with the same absolute configuration were prepared from the (−)-diol and their chiroptical properties were recorded. The absolute configuration of this series of compounds was determined to be 1R, 5R by a chemical correlation with (R)-(−)-3-phenylbutanoic acid via (−)-1,3-diphenylglutaric acid and (−)-2,4-diphenylpentane.

7-t-Butyl-9-trimethylsilyl-2,4,6-nonatrien-8-ynal prepared from 5-t-butyl-7-trimethylsilyl-2,4-heptadien-6-ynal diethyl acetal was converted into 8-t-butyl-1,3,5,7-decatetraen-7-ynyl t-butyl ketone. Treatment of the tetraenyne ketone with potassium hydroxide in liquid ammonia gave 22-membered cyclic glycol in a high yield. Reductive dehydroxylation of the cyclic glycol by tin(II) chloride and hydrogen chloride yielded tetra-t-butylbisdehydro[22]annulene in good yield. The [22]annulene was found to be strongly diatropic and conformationally stable.

The detailed molecular structures of substituted cyclopenta[b]thiapyrans were studied by means of 1H-NMR spectroscopy and X-ray diffraction method.

Isomeric 3- or 4-chlorotriptycene-7-carboxylic acid was synthesized from sodium anthraquinone-β-sulfonate and resolved with quinidine methohydroxide. The absolute configurations of (−)-3-chloro- and (−)-4-chlorotriptycene-7-carboxylic acids could be determined to be 1S,6S and 1S,6R, respectively, by the chemical correlation with (+)-2,5-dimethoxy-8-chlorotriptycene whose absolute configuration was proved to be 1R,6S by X-ray and chemical means.

Tetrakisdehydro[14]annuleno[20]annulene consisting of an aromatic bisdehydro[14]annulene and an antiaromatic trisdehydro[20]annulene has been synthesized. The 1 H NHR spectra clearly indicate the induction of para- and diamagnetic ring currents in each of the [4n]- and [4n+2]-rings, respectively.

Tetrakisdehydro[16]annuleno consisting of trisdehydro[16]annulene and bisdehydro[18] annulene has been synthesized. Induction of para- and diamagnetic ring currents in 16- and 18-membered rings, respectively, was clearly recognized by the 1H NMR spectroscopy. A marked suppresion of the diatropicity in the 18π moiety was observed in the same trend as observed in tetrakisdehydro[14]annuleno[16]annulene.

The title compound (VII) was synthesized in an optically active form and the chiroptical properties were recorded. The absolute configuration was determined by chemical correlation method.