The structure and absolute configuration of heterophylloidine

The structure and absolute configuration of heterophylloidine, a new C₂₀-diterpenoid alkaloid isolated from $\text{Aconitum heterophylloides}$ Stapf, have been determined with the aid of ¹³C NMR spectral data and single-crystall X-ray analysis of the product obtained by treatment of heterophylloidine with aqueous hydrobromic acid.     

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.     

奇蒿内酯晶体结构及绝对构型的测定

奇蒿内酯是从中草药刘寄奴提取的新化合物.用X射线单晶衍射方法确定了其三维结构,此单晶属单斜晶系,空间群:P21,晶胞参数:a=12.184(7),b=7.480(14),c=10.424(9)A,β=-104.44(6);Z=2.用直接法RANTAN)得分子初结构模型,采用块对角矩阵最小二乘法对此初结构进行修正,最后一致性因子R=0.085.并利用氧原子反常散射确定了分子的绝对构型。     

Crystal structure and absolute configuration of guan-fu G base methyliodide

Guan-fu base G is a new alkaloid isolated from root tuber of Aconitum coreanum Le'vl Raipaics. Guan-fu base G methyliodide crystallizes in orthorhombic system, space group D4/2-P2₁2₁2₁, with dimensions: a = 16.87Å, b = 16.93Å, c = 10.09Å; Z = 4. The three dimensional data were collected on a Phillips PW-1100 four-circle diffractometer with Mo K_a radiation. The structure was solved by heavy-atom method and subsequently successive Fourier syntheses. The structure was refined by block-diagonal matrix least squares methods to R = 0.0578 for 2848 reflexions. The absolute configuration was determined by computation of the R factor for the two possible configurations using anomalous scattering of iodine.     

The structure,absolute configuration and biosynthesis of nortiliacorinine a

The incorporation of (±)-norcoclaurine, (±)-coclaurine, (±)-N-methylcoclaurine and dehydro-N-methylcoclaurine into nortiliacorinine A in Tiliacora racemosa colebr has been studied and specific utilisation of the (±)-coclaurine demonstrated. The evidence supports oxidative dimerization of two coclaurine units to give nortiliacorinine A. Experiments with (±)-N-methylcoclaurine and (±)-[1-³H, N-¹⁴CH₃]N-methylcoclaurine established that only one N-methylcoclaurine unit is specifically utilised to constitute that “half” of the base which had phenolic OH group in the benzylic portion and further demonstrated that the H atom at the asymmetric centre in the 1-benzylisoquinoline precursor is retained in the bioconversion into nortiliacorinine A. Double labelling experiment with (±)-[1-³H, 6,0-¹⁴CH₃]N-methylcoclaurine showed that O-Me function of the precursor is lost in the bioconversion into nortiliacorinine A. Parallel feedings of (+)-(S)- and (-)-(R)-N-methyl-coclaurines and (-)-(S)-, and ( + )-(R)-coclaurines revealed that the stereo-specificity is maintained in the biosynthesis of nortiliacorinine A from 1-benzylisoquinoline precursors and established ‘S,S’-configuration at the two asymmetric centres in nortiliacorinine A.     

关附庚素碘甲烷盐的晶体结构和分子构型

关附庚素是从毛茛科植物黄花乌头块根中分得的一种生物碱。关附庚素碘甲烷盐的晶体属正交晶系;空间群为D_2~4-P2_12_12_1;晶胞中含四个分子;晶胞参数a=16.87A,b=16.93A,c=10.09A。强度数据用PW1100四圆衍射仪收集,采用MoK_a辐射。晶体结构用重原子法导出;碘原子由Patterson法求得;其它卅五个非氢原子的坐标由三维Fourier综合确定。结构用块对角矩阵进行最小二乘修正,然后加卅六个氢原子位置又修正了一轮,最后的R因子为0.0578,并根据反常散射确定绝对构型。     

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.