X-ray structural investigation of alkaloids. III. Molecular structure and absolute configuration of (+)-excelsine

By a complete x-ray structural investigation, the structural formula of (−)-pseudokopsinine has been refined and its absolute configuration has been determined.     

The x-ray structural investigation of alkaloids I. Molecular structure and absolute configuration of (+)-cocculine

Summary An x-ray structural investigation of the alkaloid (+)-cocculine in the form of the hydrobromide has been performed. The bond lengths and valence angles are the usual ones. The conformations of the rings are: A — envelope⁴E; B — half-chair⁹T₅; C — half-chair¹⁰H₅. The absolute configuration 3R,5S has been established.Institute of Heteroorganic Compounds, Academy of Sciences of the USSR. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 395–400, May–June, 1975.     

X-ray structural investigation of alkaloids. II. Molecular structure and absolute configuration of (?)-pseudokopsinine

Summary By a complete x-ray structural investigation, the structural formula of (–)-pseudokopsinine has been refined and its absolute configuration has been determined.Institute of Heteroorganic Compounds, Academy of Sciences of the USSR, Moscow. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 197–206, March–April, 1976.     

X-ray structural study of alkaloids. VII. Structure and absolute configuration of severidine

A physicochemical and complete x-ray structural investigation of the new alkaloid severidine isolated from the epigeal part ofKorolkowia sewerzowii Regel has been performed. The crystals were investigated in the form of severidine hydrochloride, C₂₇H₄₃NO₅·HCl, rhombic,a=12.642, b=12.882, c=16.621 Å, z=4, space group P2₁2₂2₁, at ?120°C. The structure was interpreted by the direct method and was refined to R=0.039. The hydrogen atoms were revealed. The absolute configuration was established by means of the Hamilton test. The skeleton of the cation is constructed of bicyclic and tricyclic fragments linked by an ordinary C-C bond. All the rings have the chair conformation. The bond lengths and valence angles are normal.     

X-ray structural study of alkaloids. VII. Structure and absolute configuration of severidine

A physicochemical and complete x-ray structural investigation of the new alkaloid severidine isolated from the epigeal part ofKorolkowia sewerzowii Regel has been performed. The crystals were investigated in the form of severidine hydrochloride, C₂₇H₄₃NO₅·HCl, rhombic,a=12.642, b=12.882, c=16.621 Å, z=4, space group P2₁2₂2₁, at –120°C. The structure was interpreted by the direct method and was refined to R=0.039. The hydrogen atoms were revealed. The absolute configuration was established by means of the Hamilton test. The skeleton of the cation is constructed of bicyclic and tricyclic fragments linked by an ordinary C-C bond. All the rings have the chair conformation. The bond lengths and valence angles are normal.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. A. N. Nesmeyanov Institute of Organometallic Compounds, Academy of Sciences of the USSR, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 342–349, May–June, 1981.     

X-ray structural investigation on alkaloids V. Crystal and molecular structure of sibiricine

Summary A complete x-ray structural investigation of the spirobenzy1isoquinoline alkaloid sibiricine in the form of the base has been carried out. The bond lengths and valence angles are the usual ones.Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 752–758, November-December, 1978. Original article submitted July 4, 1978.     

X-ray structural investigation of alkaloids VI. Crystal structure of the alkaloid parfumine

A complete x-ray structural investigation of the alkaloid parfumine has been performed. The lengths of the bonds and the valence angles have the usual values. Benzene rings A and D are planar, B a distorted half-chair^C(6)H_N, and rings C and E are flattened envelopes, E_C(14) and^C(19)E, respectively.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Institute of Heteroorganic Compounds, Academy of Sciences of the USSR, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 66–73, January–February, 1980.     

Molecular structure and absolute configuration of α-chloromercurycamphene

Conclusions The methods of x-ray structural analysis have been used to determine the crystal and molecular structures and the absolute conformation of -chloromercurycamphene.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2021–2026, September, 1979.     

X-ray structural investigation of glyoxime derivatives II. Molecular and crystal structure of diaminotetraoxime

A. N. Nesmeyanov Institute for Heteroorganic Compounds, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 1, pp. 179–180, January–February, 1989.     

Total synthesis, structure revision, and absolute configuration of (+)-yatakemycin

The total synthesis of the reported structure 2 for yatakemycin, an exceptionally potent, naturally occurring antitumor agent disclosed in 2003, and its lack of correlation with the natural product are detailed. On the basis of spectroscopic distinctions between 2 and yatakemycin, the natural product structure was reformulated as 3, now bearing a thiomethyl ester versus thioacetate in the left-hand subunit. Total synthesis of 3 provided a compound nearly identical to but still subtly distinct from the natural product. A second reformulation of the yatakemycin structure as 1, incorporating the alternatively substituted right-hand subunit as well as the initial thiomethyl ester reformulation, was confirmed by total synthesis of both (+)- and ent-(-)-1 in studies that also unambiguously established the absolute configuration of the natural product.     

X-ray structural investigation of the steroid alkaloids edpetilidinine and sevcoridinine

The spatial structures of the alkaloids edpetilidinine and sevcoridinine have been determined by x-ray structural analysis and this has permitted a corrected variant to be put foward for the structures of the edpetilinine and sevcorine.Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 864–869, November–December, 1987.     

X-ray structural investigation of the steroid alkaloids edpetilidinine and sevcoridinine

The spatial structures of the alkaloids edpetilidinine and sevcoridinine have been determined by x-ray structural analysis and this has permitted a corrected variant to be put foward for the structures of the edpetilinine and sevcorine.