Tetraacetylenic compound

The tetraacetylenic compound (-)-minquartynoic acid was synthesized in the laboratory of B.W. Gung from commercially available azelaic acid monomethyl ester using a one-pot three-component Cadiot-Chodkiewitz reaction as the key step. This natural product shows strong anti-cancer and anti-HIV activity. One of the alkyne components was prepared using the modified Seyferth-Gilbert homologation. 

X-ray analyses of the two twelve membered tetraacetylenes (42)167) and (43)168) have been carried out. The bond angles at the triple bonds must be bent by about 10-15°, but the exact structural parameters of both compounds have not yet been published. 

PE spectra of the two angle strained cyclopolyynes 1,5-cyclooctadiyne (35)177) and the twelve membered tetraacetylene (43)88) have been measured and interpreted with the aid of semiempirical and ab initio molecular orbital calculations. In both compounds evidence for through-space and through-bond interactions between the acetylene moieties has been found 88,177). The compound (43) has been described on the basis of these results as weakly antiaromatic88). 

Dialkyl 1,3-diacetyIenes usually absorb in the ultraviolet region, Amax 226, 239 and 253 nm. Of a series of cyclic tetraacetylenes (8), two higher homologues, 8c and 8d, show absorption spectra similar to that of acyclic compounds, whereas the trimethylene homologue (8b) demonstrates strikingly different features in its absorption spectrum (0 a red shift of 9nm and (//) appearance of a new band at 246 nm. This is attributed to the marked transannular electronic interaction in 8b, in... 

In many PE spectra, especially in compounds with triple bonds, such a vibrational fine structure can be observed. The observed energy differences between the vibrational states of the radical cation can be compared with IR frequencies of the ground state and may be helpful in the assignment of the PE spectrum. In many cases vibrational fine structures of 0.25 eV can be observed. This value corresponds to the characteristic triple-bond IR frequencies around 2000 cm. As an example we show the first PE bands of tetraacetylene (octatetrayne) (figure 3). All four bands of tetraacetylene show vibrational fine structure with the following spacing v (cm ) (1) 2100, (2) 1950, (3) 1960, (4) 400. 

Treatment of the trichloroenediyne 22 with butyllithium, followed by morpholine, results in l,6-dimorpholinohexa-l,3,5-triyne (23). The push-pull triacetylene 24 is similarly produced from compound 22, butyllithium and methyl chloroformate. The corresponding tetraacetylene 25 has also been reported. These compounds have low thermal stability ... 

This synthetic route was adopted for the synthesis of 4,5-helical diarylphenanthrenes and related compounds [284, 292, 293]. Condensation of tetraacetylene 3.592 with two equivalents of ketone 3.544 followed by the above sequence of reactions led to atropoisomers... 

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