Organosilicon chalcogenides with trisilane units - bicyclo[3.3.1]nonanes, bicyclo[3.2.2]nonanes and spiro[4.4]nonanes

Treatment of 1,2,3-trichloropentamethyltrisilane (1) with H₂S/NEt₃ results in the formation of a mixture of two isomers of (Me₅Si₃)₂S₃ with a bicyclo[3.3.1]nonane (2a) and a bicyclo[3.2.2]nonane (2b) skeleton, while the reaction of 1 with Li₂Se yields one product only, (Me₅Si₃)₂Se₃ (3a), with a bicyclo[3.3.1]nonane structure. Besides ¹H, ¹³C, ²⁹Si and ⁷⁷Se NMR spectroscopy 3a has also been characterized by a crystal structure analysis.Compounds Si(SiMe₂EMR₂E)₂ (5a-h: MR₂: SiMe₂ (5a, c, d), SiPh₂ (5b), GeMe₂ (5e, f), SnMe₂ (5g, h); E=S (5a, b, e, g), Se (5c, f, h), Te (5d)) with a spiro[4.4]nonane skeleton have been obtained in mixture with varying amounts of the corresponding six-membered rings (R₂ME)₃ by reactions of mixtures of 1,2,2,3-tetrachlorotetramethyltrisilane (4) and diorganodichlorosilanes, Me₂GeCl₂ or Me₂SnCl₂, with H₂S/NEt₃, Li₂Se or Li₂Te and have been characterized in situ by multinuclear NMR spectroscopy (¹H, ¹³C, ²⁹Si, ¹¹⁹Sn, ⁷⁷Se, ¹²⁵Te) and GC-MS.     

13C NMR spectra of 3- and 5-substituted flavone derivatives

Summary The¹³C NMR of a number of 3- and 5-hydroxyflavones and of 3- and 5-methoxyflavones have been studied for the first time and all the signals have been assigned. A comparison of the chemical shifts of the¹³C nuclei with the acidity and basicity parameters of the compounds investigated and with the results of calculations of -charge density has been made. It has been shown that the chemical shifts of the individual signals in the¹³C NMR spectra are qualitatively connected with estimates of the reactivities of the compounds studied.Irkutsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR. A. A. Zhdanov Irkutsk State University. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 513–519, July–August, 1977.     

13C NMR spectroscopy of cyclopentenpoliols

The ¹³C NMR spectral parameters of eleven cyclopentenpoliols are discussed. Chemical shift criteria to distinguish isomeric 3' and 4' monodeoxy eucommiols have been clearly established.     

The mass-spectral fragmentation of bicyclo[3.3.1]nonanes

The mass spectra of twelve bicyclo[3.3.1]nonanes have been recorded. The high number of metastables observed, exact mass measurements of the ions and low ionising voltage spectra, permitted the rationalisation of most of the fragmentation pathways. The 1-phenyl substituent triggers the major fragmentation in the hydrocarbon, whereas it has minor influence in the oxygenated compounds. Significant differences in the abundance of [M ? H₂O]⁺ ions for stereoisomeric alcohols of this series have been observed.     

3,7-disubstituted bicyclo [3.3.1] nonanes—II : Synthesis and conformation of some 3,7-disubstituted 9-oxobicyclo [3.3.1] nonanes

Condensation of pyrrolidine enamines of 4-alkylcyclohexanones with methyl α-(bromomethyl)acrylate affords methyl 7β- and 7α-alkyl-9-oxobicyclo [3.3.1] nonane-3α-carboxylates in a ratio of 3:2. The mechanism of the annelation reaction is discussed. The conformations of the reaction products and their epimers have been studied by means of PMR spectroscopy.     

13C NMR spectra of some furocoumarins

¹³C NMR spectra of some naturally occurring furocoumarins and derivatives have been examined. The assignment of chemical shifts for all the C atoms has been achieved by using techniques recently reported by Bose et al.     

3,7-disubstituted bicyclo[3.3.1]nonanes—III: Synthesis and conformation of bicyclo[3.3.1]nonane-3α,7α-dicarboxylic acid,its dimethyl ester and some other 3,7-disubstituted bicyclo[3.3.1]nonanes; adamantane as an integrated holding system

The conformation of bicyclo[3.3.1]nonane-3α,7α-dicarboxylic acid and its dimethyl ester has been studied by comparing ¹H NMR and ¹³C NMR spectra of these compounds with those of some model 3,7-disubstituted bicyclo[3.3.1]nonanes, fixed in a single conformation by the use of adamantane as an integrated holding group or by means of suitable substitution. It is shown that the dicarboxylic acid and its dimethyl ester exist predominantly as two rapidly interconverting (identical) chair-boat conformations with distinctly flattened rings; the population of the double-boat conformation appears to be very small.     

1H NMR study on the inclusion of bicyclo[3.3.1]nonanes in cyclodextrins

- and -cyclodextrins were found to form 1:1 inclusion complexes with 2,6- and 2,9-substituted bicyclo[3.3.1]nonanes. The binding constants and the structure of the complexes were estimated from titration studies and 2D ROESY experiments.     

Direct oxidative functionalization of saturated dispiro-cyclopropanated bicyclo[3.3.1]nonanes

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Biosynthese de la botryodiplodine,mycotoxine de penicillium roqueforti: Incorporations d'acetate[1-13C], [2-13C], [1-2 13C]et d'acide orsellinique 2-13C-carboxyle 13C], [3-4 13C]

Incorporations of [1-¹³C], [2-¹³C], [1-2¹³C]acetate and [2-¹³C, carboxyl-¹³C], [3-4¹³C]orsellinic acid into botryodiplodin indicate that this mycotoxin is biosynthesized by the polyketide pathway. Orsellinic acid is a precursor of botryodiplodin. A biosynthetic pathway, using orsellinic acid as precursor, is proposed.     

1H NMR spectroscopic study of the interaction between cyclodextrins and bicyclo[3.3.1]nonanes

The formation and structure of inclusion complexes of 2,6- and 2,9-substituted bicyclo[3.3.1]nonanes with- and-cyclodextrin (CD) has been investigated by high-resolution¹H NMR spectroscopy.- and-CD were found to form 1:1 inclusion complexes and the binding constants were estimated from titration studies. 2D ROESY experiments provided insight into the structure of the complexes.Presented in part at the 8th International Cyclodextrin Symposium, Budapest, March 30–April 2, 1996.     

13C NMR of pterocarpans

¹³CNMR spectra of eight pterocarpans are reported Assignments are based on multiplicities and second-order features in off-resonance decoupled spectra and on chemical shifts in model compounds. Comparison of the degree of long-range (C, H) coupling in ¹H-coupled spectra is found useful     

13C NMR spectra and structure of some coumarin derivatives

The results are given of a study of the¹³C NMR spectra of (–)-3(R)-decursinol, obtusifol, bergapten, isoimperatorin, and oxypeucedanin and its hydrate. The possibility has been shown of using the principle of additive contributions in the assignment of the signals of the carbon atoms in the compounds under investigation.Institute of Toxicology, Ministry of Health of the USSR, Leningrad. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 301–307, May–June, 1982.     

The electron impact induced fragmentations of some 7-alkyl-3-oxabicyclo[3.3.1]nonanes

The mass spectra of a series of 7-alkyl substituted 3-oxabicyclo[3.3.1]nonanes are recorded. The fragmentation has been studied by the use of the metastable DADI and defocussing techniques. The character of the alkyl group is found to influence the fragmentation pattern. Stereoselective fragmentations for the 7-t-butyl derivatives are observed. In the endo-isomer, in contrast to the exo-isomer, a transannular hydrogen transfer plays a role.     

13C NMR of some insect attractants and related compounds

Ten insect attractants, a number of intermediates in their synthesis and some related compounds were characterized by their 13C NMR spectra. The chemical shifts of the allylic carbon atoms allowed neat distinction between E and Z isomers of alkenic compounds.     

Fourier 13C NMR and PMR including 13C satellites of oriented cyanopropyne

Fourier ¹³C and proton NMR spectra of cyanopropyne partially oriented by a nematic phase have been recorded and interpreted. It is shown that more accurate measurements are obtained much more rapidly by observing ¹³C satellites by Fourier PMR than by direct observation of the ¹³C spectrum. The geometry has been extracted from direct couplings; a small but systematic discrepancy with microwave spectroscopy is observed for the carboncarbon bond lengths.     

13C NMR spectra of bicyclo[3.3.1]nonanones and their derivatives

Conclusions An assignment was made of the lines in the¹³C NMR spectra of the mono- and diketones of the bicyclo[3.3.1]nonane series, and of the hydrolysis products of bicyclo[3.3.1]nonane-2,9-dione and its 7-benzoyloxy derivative.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2386–2389, October, 1979.     

Substituent effects in 13C NMR spectra of 6-endo substituted 9-thiabicyclo[3.3.1]non-2-enes

A number of new 6-endo-X-9-thiabicyclo[3.3.1]non-2-enes have been synthesized (X = cyano, carbimino-methoxy, carbomethoxy, carboxylic acid, aminomethyl, tosylmethyl and methyl). The ¹³C NMR spectre of six of these compounds were measured along with those of several known analogues with X = chloro, hydroxy, hydrogen and deuterium. Assignments were carried out with the aid of hetero (¹³C-¹H) and homo (¹H-¹H) nuclear decoupling techniques. For the compounds with X = H and X = Cl our assignments differ from those published previously and hence result in different values of the substituent-induced chemical shifts (SIS-values) in the 9-thiabicyclo[3.3.1] non-2-ene skeleton.Some of the existing theories regarding SIS-values in multiple substituted cyclic compounds are reviewed and reconsidered in view of the new evidence presented here. Mutual repolarization of the C-hetero atom bonds is proposed as an important factor. In the systems under study in this paper an electron donation of the sulfur atom to the endo C₆-X group is postulated in order to explain the SIS-values on saturated C atoms. The signals of the unsaturated carbons are assigned assuming that electric field effects play a major role.     

13C NMR spectra of some coumarins of Haplophyllum obtusifolium

Coumaris ofHaplophyllum obtusifolium Ledeb. — obtusinin, capensin, and fraxetin 7-O--D-glucopyranoside — have been investigated by¹³C NMR spectroscopy. Several distinctive features of their NMR spectra have been observed. A complete assignment of the¹³C NMR spectra of these coumarins has been made and their structures have been confirmed.Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 796–799, November–December, 1987.