Crystal and molecular structure of 4-isopropyltropolone (β-thujaplicin)

Derry, J. E.; Hamor, T. A.

doi:10.1039/p29720000694

Cited by 21 publications

(17 citation statements)

References 0 publications

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“…The puckering in the rings may alternatively be described by the torsion angles in Fig. 3 found here agrees closely with that reported for other structures containing troponoid rings (Margulis, 1974(Margulis, , 1975Koerntgen & Margulis, 1977;Shimanouchi & Sasada, 1973;Derry & Hamor, 1972;Hamor & Derry, 1973;Karlsson, Pilotti & Wiehager, 1973, 1976Berg, Karlsson, Pilotti & Wiehager, 1976). However, the pattern of ring puckering and the extent of non-planarity seem to vary among these compounds.…”

Section: Resultssupporting

confidence: 79%

The crystal structure of colchicine. A new application of magic integers to multiple-solution direct methods

Lessinger¹,

Margulis²

1978

Acta Crystallogr Sect B

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The mitotic spindle inhibitor colchicine, C22H25NO6, crystallizes as a dihydrate in space group P21, a = 17.08, b = 10.70, c = 13.88 A, fl = 117.9 °, Z = 4(C22H25NO6.2H20)/unit cell. The crystal structure was solved by a multiple-solution direct method in which unknown starting phases ~l are represented using 'magic integers': tp I = mix. An appropriate choice of integers m I and sampling of the variable x allows a drastic reduction in computing time and a great increase in structure-solving capability compared to the widely used method in which all unknown phases are permuted among the four values 45, 135, 225, 315 °. The crystal structure of colchicine dihydrate was refined by least squares to R = 0.052 for 2322 observed X-ray reflections. The two independent colchicine molecules have very similar conformations in the crystal. The troponoid rings have alternating bond lengths, and are not precisely planar. These rings make dihedral angles with the planar benzene rings of 53 ° in one molecule of eolchicine, 51 o in the other. The four independent water molecules are all found in a distinct region in the crystal, which is held together by a complex hydrogenbond network. Two methoxy-group O atoms of colchicine act as hydrogen-bond acceptors, the one on the troponoid ring participating in a bifurcated hydrogen bond.Colchicine (I), the principal active substance of the autumn crocus, has a remarkable range of biological effects. The most studied of these is its arrest of mitosis, believed to result from the specific strong binding of eolehicine to the protein tubulin, preventing the assembly of tubulin into mierotubules which form the mitotic spindle (Soifer, 1975). Colchicine is also capable of relieving the pain of gout (for which it has been used since ancient times), of inducing polyploidy * Present address:

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Section: Resultssupporting

confidence: 79%

The crystal structure of colchicine. A new application of magic integers to multiple-solution direct methods

Lessinger¹,

Margulis²

1978

Acta Crystallogr Sect B

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“…Standard deviations are estimated to be 0.004 A and 0.3 ° respectively, but somewhat larger values of about 0.006 A and 0.4 ° are expected for the bonds involving atoms C(10), C(ll) and C(12). ~,-Thujaplicin exhibits bond-length alternation in the seven-membered ring, as do the related compounds tropolone (Shimanouchi & Sasada, 1973), fl-thujaplicin (Derry & Hamor, 1972), chanootin (Karlsson, Pilotti & Wiehager, 1973) and utahin (Karlsson, Pilotti & Wiehager, 1976). The n-electron system in the trop- olone moiety is only partially delocalized with some double-bond fixation both for C-C and C-O bonds.…”

mentioning

confidence: 99%

5-Isopropyltropolone, γ-thujaplicin

Berg¹,

Karlsson²,

Pilotti³

et al. 1976

Acta Crystallogr Sect B

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“…In a recent paper on the crystal structure of 4-isopropyltropolone (IPT) (Derry & Hamor, 1972), it was noted that the bond lengths did not agree with those observed in the crystal structure of tropolone by Shimanouchi & Sasada 1970), where, apart from a long C(1)-C(2) bond of 1.452 , ring bond lengths (mean 1.407 A) are close to the aromatic value and there is no alternation in length. IPT, in contrast, exhibits bond-length alternation in the sense predicted by the classical valence bond structure, with the C(1)-C(2) length 1.469/~, close to the C(sp2)-C(sp 2) singlebond value.…”

Section: Olji-p-o'111mentioning

confidence: 92%

“…The slightly greater degree of non-planarity of the ring in IPT is consistent with the smaller degree of n-electron delocalization in this molecule indicated by the comparison of bond lengths. The fact that the tropolone ring conformation appears to differ from the tropone ring conformation in the manner indicated above may be a consequence of the greater degree of electron delocalization in tropolones as compared with tropones (Derry & Hamor, 1972;Shimanouchi & Sasada, 1973), and of the partial double-bond character of the C(2)-O(2) bond.…”

Section: Olji-p-o'111mentioning

confidence: 98%