Substituent increments for the 1H-NMR. Chemical shifts of the 18- and 19-methyl protons of steroids. Part II: 9alpha, 10beta(normal)-steroids

In Part II of this series we report 292 substituent increments for the ¹H-NMR. chemical shifts (solvent: CDCl₃) of the 18- and 19-methyl protons of 9α,10β(normal)-steroids relative to 5α,9α,10β,-androstane. The increments were calculated by a least-squares procedure from 988 spectra of 681 different steroids.     

14-methyl steroids. Part 3. Synthesis of (±)-14α-methyl-9β-estradiol and related 14α-methyl-19-norsteroids

Catalytic hydrogenation of a totally synthetic mixture of (±)-3-methoxy-14-methyl-14α-estra-1,3,5( 10), 9(11)-tetraen-17-one(1) and the corresponding 1,3,5(10),8-tetraen-17-one (2) gives a mixture of 14α-methyl-8β,9β-, -8α,9α-, and -8β,9α-estrones, which is converted into the 17β-hydroxy-mixtures. t-Butylation gives a separable mixture of the three isomers, of which (±)-17β-t-butoxy-3 methoxy-14-methyl-9β,14α-estra-1,3,5(10)-triene(6) is the major component. The corresponding 14α-methylestradiols are prepared. A practical synthesis of (±)-14-methyl-14α-estra-1,3,5(10), 6,8-pentaene-3,17β-diol(25) is described, and it is shown that DDQ dehydrogenation of 1,3,5(10),9(11)-tetraenes in this series leads exclusively to the corresponding 1,3,5(10),6,8,11-hexaenes, whereas that of 1,3,5(10),8-tetraenes gives only 1,3,5(10),6,8-pentaenes.     

Substituent effects on fluorine - 19 chemical shifts in benzobicyclo(2.2.2)octen-1-yl fluorides

Inverse ¹⁹F substituent chemical shifts (SCS) of $\text{m}$- and $\text{p}$-substituted benzylfluorides are shown to have their origin in hyperconjugation involving the CF δ - bond.     

9(10 leads to 19)abeo steriods. Total synthesis of abeo-estradiol, abeo-estradiol 3-methyl ether, and 17 alpha-ethynyl abeo-estradiol 3-methyl ether.

Total synthesis of abeo-estradiol, abeo-estradiol 3-methyl ether, and 17alpha-ethynyl abeo-estradiol 3-methyl ether is described. Stereochemical assignments in 9(10 through 19) abeo-estradiol and its 3-methyl ether were made by X-ray analysis of the 17-keytone. Single crystals were grown by evaporation of a petroleum ether-ethanol solution and the intensities of 2619 diffraction spectra were measured, of which 1036 had intensity greater than twice the background. The structure was refined by full-matrix least-squares techniques and all hydrogen atoms were located in the Fourier difference syntheses.     

Nuclear magnetic resonance studies of phosphorus(v) pesticides : Part I. Chemical shifts of protons as a means of identification of pesticides

Correlations of structural and proton chemical-hift data for 40 commercial phosphorus(V) pesticides are reported. Correlations of structure with the phosphorus coupling constants are discussed, and general trends are noted which aid in the use of NMR as a tool for identification and analysis of phosphorus(V) compounds.     

(10Z)- and (10E)-19-fluoro-1alpha,25-dihydroxyvitamin D3: an improved synthesis via 19-nor-10-oxo-vitamin D

An efficient synthetic route to (10Z)- and (10E)-19-fluoro-1alpha,25-dihydroxyvitamin D3 was developed. The key feature of this pathway is the introduction of a 19-fluoromethylene group to a (5E)-19-nor-10-oxo-vitamin D derivative. The 10-oxo-compound was obtained via a 1,3-dipolar cycloaddition reaction of (5E)-1alpha,25-dihydroxyvitamin D with in situ generated nitrile oxide followed by ring cleavage of the formed isoxazoline moiety with molybdenum hexacarbonyl. Conversion of the keto group of (5E)-19-nor-10-oxo-vitamin D to the E and Z fluoromethylene group was achieved through a two-step sequence involving a reaction of lithiofluoromethyl phenyl sulfone followed by the reductive desulfonylation of the alpha-fluoro-beta-hydroxy sulfone. The dye-sensitized photoisomerization of the (5E)-19-fluorovitamin D afforded the desired (5Z)-19-fluorovitamin D derivatives, (10Z)- and (10E)-19-fluoro-1alpha,25-dihydroxyvitamin D3.     

反式-9, 10-二氢-9, 10-二(1-萘基)-9, 10-菲二醇的包合现象 与晶体结构

按文献方法合成了一个螯形主体分子,反式-9,10-二氢-9,10-二(1-萘基)-9,10-菲二醇。研究发现该主体可以和一些含氮杂环化合物形成一定比例的晶体包合物。用X-射线衍射分析二环己胺包合物的晶体结构表明,包合物中主客体之间存在O-H…N氢键相互作用,客体分子包合在主体分子形成的空腔中。     

Substituent effects in π-(tricarbonylchromium)arenes: I. 1H NMR Spectroscopy of alkylsubstituted π-(tricarbonylchromium)benzenes

Some thirty substituted π-(tricarbonylchromium)benzenes, including some crowded alkylsubstituted complexes, e.g. (l',l'-diethylpropyl)-, (1'-t-butyl-2',2'dimethylpropyl)-, 1,2-di-t-butyl- and 1,2,4-tri-t-butyl-π-(tricarbonylchromium)benzenes, have been prepared. ¹H NMR spectra have been recorded from acetone solutions of the complexes. Using the chemical shift increments of the aromatic protons on complex formation of C₆H₅CH-t-Bu₂, as a reference for the eclipsed conformation with the substituent staggered with respect to the carbonyl ligands, the contribution of this conformer to the conformational equilibrium of the other monoalkylsubstituted complexes has been estimated, ¹H NMR spectroscopy turns out to be a useful probe in conformation analysis of π-(tricarbonylchromium)arenes.     

Dependence of 1H NMR chemical shifts of geminal protons of glycosyloxy methylene (H2-26) on the orientation of the 27-methyl group of furostane-type steroidal saponins

An approach based on the difference (Delta(ab) = delta(a) - delta(b)) between the 1H NMR chemical shifts (delta(a), delta(b)) of the geminal protons of glycosyloxy methylene (H2-26) (Delta(ab) = <0.48 for 25R; Delta(ab) = >0.57 for 25S) is proposed for ascertaining 25R/25S orientation of the 27-methyl group of furostane-type steroidal saponins. These studies suggested the 25R-orientation of the 27-Me group for the furostanol glycosides isolated by Wu et al. from Tribulus terrestris.     

Synthesis of (10Z)- and (10E)-19-fluoro-1alpha,25-dihydroxyvitamin D3: compounds to probe vitamin D conformation in receptor complex by 19F-NMR

To study the interaction of vitamin D with its receptor by 19F-NMR, (5Z,10Z)- and (5Z,10E)-19-fluoro-1alpha,25-dihydroxyvitamin D3 were synthesized starting from vitamin D2 via electrophilic fluorination of vitamin D-SO2 adducts as the key step. Regio- and stereoselective electrophilic fluorination at C(19) of vitamin D-SO2 adducts was achieved under the conditions using (PhSO2)2NF and bulky bases. The stereochemistry of the addition and elimination of SO2 of various vitamin D derivatives was studied in detail. SO2 causes Z-E isomerization of the 5,6-double bond of vitamin D and adds to the resulting (5E)-isomer from the sterically less hindered side opposite to the substituent at C(1). Elimination of SO2 from 19-substituted vitamin D-SO2 adducts proceeded exclusively in a suprafacial manner with respect to the diene part under either thermal or reductive conditions. Dye-sensitized photochemical isomerization of 19-fluorovitamin D derivatives was studied in detail. The rapid isomerization at the 5,6-double bond was followed by the slow isomerization at the 10,19-double bond to yield the (5E,10Z)-isomer (by nomenclature of the 1-OH derivatives) as the major product. (10Z)- and (10E)-19-Fluorovitamin Ds were also interconverted thermally probably via the corresponding previtamin D by 1,7-sigmatropic isomerization.     

(1-(Dimethylamino)-2-(diphenylphosphino)ethane)(eta(3)-1-arylallyl)palladium Tetrafluoroborates. Preparation, Isomeric Equilibria, and Correlations of NMR Chemical Shifts with Hammett Substituent Constants

13C NMR differences of chemical shifts (delta(X) - delta(H)) of allyl carbon atoms in a series of trans-(1-(diphenylphosphino)-2-(dimethylamino)ethane)(eta(3)-1-arylallyl)palladium tetrafluoroborates, X ranging from NO(2) to OMe, correlate very well with sigma Hammett constants for C-1 and with sigma(+) for C-3, this carbon atom being in a trans relationship with the positively charged nitrogen atom.     

9-（4，5-二硫甲基-1，3-二硫杂环戊烯-2甲叉基）蒽-10（9H）-酮的合成及量子化学计算

设计合成了一种新的具有D-π-A结构的有机分子，9-（4，5-二硫甲基-1，3- 二硫杂环戊烯-2-甲叉基）蒽-10（9H）-酮（C_(19)H_(14)OS_4）。以~1H NMR， FTIR，元素分析和UV-vis进行了表征。运用Gaussian 98量子化学程序包，采用 B3LYP密度泛函（DFT）的方法，在6-31G（d）水平上对分子的几何构型进行了优化 ，在优化的基础上用TDDFT的方法计算了化合物的电了防染印花谱，计算值与实验 值基本吻合，用TDHF的方法计算了它的二阶非线性光学系数，与蒽醌相比，其第一 超给化率β较大，为12.03 * 10~(-30)esu。     

Electronic effects of the 1-[CLOSO-3,3,3-(CO)3-3,1,2-ReCaB9H10]− and 1-[CLOSO-3,3,3-(CO)3-3,1,2-.MnC2B9H10]- groups

Conclusions The electronic effects of the 1-[closo-3,3,3-(CO)₃-3,1,2-ReC₂B₉H₁₀]^– (_I=-0.066; _r ^o=0.101) and 1-[closo-3,3,3-(CO)₃-3,1,2-MnC₂B₉H₁₀]^–(_I=0.090; _r ^o=0.165) groups were determined by the Taft method.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2296–2298, October, 1987.     

J. Jortner,M. Bixon (eds) Electron transfer - from isolated molecules to biomolecules,Part I. (Advances in Chemical Physics,vol. 106)

Journal of Solid State Electrochemistry -     

Conformations of the 10-membered Ring in 5, 10-Secosteroids. II. (E)-3α-Acetoxy-5, 10-seco-1 (10)-cholesten-5-one and (E)-5, 10-seco-1 (10)-cholestene-3, 5-dione

(E)-3α-Acetoxy-5, 10-seco-1(10)-cholesten-5-one ( 3 ) was synthesized by fragmentation of 3α-acetoxy-5α-cholestan-5-ol ( 1 ) using the photochemical version [3] of the lead tetraacetate reaction [4], and transformed into the corresponding 3-oxo-compound ( 5 ). Two conformations ( A and B ) were deduced for the 10-membered ring of 3 by analysis of the ¹H- and ¹³C-NMR. spectra in toluene. The major conformation ( A ) corresponds to that found in the solid state by X-ray analysis. According to its NMR. spectra in toluene, the medium-sized ring of the diketone 5 exists also predominantly in two conformations, the major one being analogous to A (the solid-state conformation of the 3β-acetoxy isomer ( 9 ) [1]) and the minor one to A (see above). The stereochemistry of the acidcatalyzed and thermal cyclisations of 3 as well as of the corresponding 5-oxime is discussed in terms of conformational factors.