The behaviour of some functionally substituted α-allenic alcohol derivatives toward organocopper(I) species

Trimethylsilyl ethers of 2,3-hexadien-5-yn-1-ols (1) undergo carbocupration at the terminal triple bond, and this reaction has been used to prepare, among other species, the trimethylsilyl ethers of 8-trimethylsilyl-2,3,5-octatrien-7-yn-1-ols(6a and 7a). When the terminal triple bond of 1 is protected with a trimethylsilyl group S_N2′-like displacements take place upon addition of RCu, with predominant formation of E-dienynes in which H is present instead of R, especially when s-BuCu is used. Only when R is methyl is the R group transferred. On the other hand, smooth formation of dienynes bearing the R group are observed upon reaction of methanesulfinates with RCu; in this case, however, the configuration of the dienynes is mainly Z. A mechanistic rationalization of the results is proposed.     

Recherches sur la formation et la transformation des esters LXXXII [1]. Sur la différenciation entre structures δ2-amino-2 ou imino-2 dans des composés S,N-hétérocycliques pentagonaux et hexagonaux à cycle par ailleurs saturé

Comparison of the NMR. spectra in CDCl₃ of the heterocyclic bases obtained from the cyclisation of ω-(N-thiocarbamoylamino) ethyl (or propyl)-alcohols (or their orthophosphoric or sulfuric monoesters) to those of model compounds II (n = 1 or 2) and III (n = 1 or 2) has shown that: (1) In the case of five membred rings the C?N double bond is always endocyclic (Ib, n = 1) should R be aromatic, araliphatic or aliphatic; (2) In the case of six membered rings the C?S double bond is cnclocyclic when R is aliphatic or araliphatic (Ib, n = 2), and exocyclic when R is aromatic (I a, n = 2), with the exception of 2-(o-carboxyphcnylamino)-dihydro-δ²-m (Ib, n = 2, K = o-carboxyphcnyle). In CF, COOH, all five membered rings (I b, n = 1) show a triplet for the C-4 methylenic protons, whereas all the six membered rings (Ia or I b, n = 2) with the exception of I b, n = 2, R = o-carboxyphenyle, are represented b y a double triplet for the C-4 protons (samt. protonated spccics). Only one triplet is observed when the 3 position is substituted. Thiocarbamoylation of hydrazinoethanol or its orthophosphoric or sulfuric monoesters canoccur at either of the two nitrogen atoms, thus yielding upon cyclization five- (IT′) or six-membered rings (Va or Vb). The NMR spectra of compounds I V in (CIl,), SO show a singlet for 2 amino pro-tons (3-amino) and there is no further structural problem. The NMR spectra of compounds T′ in (CT), SO show a triplet for one amino proton coupling with the neighboring methylenic protons. I n this case, mode1 compounds are needed to assign the position of the C?N double bond ( e x cyclic V a or cndocyclic V b). When R = o-carboxyphenylc, the C?N double bond is probably endoc, yclic (Vb) because this ccimpound and 2-(o-carboxyphenvlarnino)-dihydro-δ² have very similar UV spectra.     

Stereoelectronic effects on 1H nuclear magnetic resonance chemical shifts in methoxybenzenes

Investigation of all O-methyl ethers of 1,2,3-benzenetriol and 4-methyl-1,2,3-benzenetriol (3-16) by 1H NMR spectroscopy and density-functional calculations disclosed practically useful conformational effects on 1H NMR chemical shifts in the aromatic ring. While the conversion of phenol (2) to anisole (1) causes only small positive changes of 1H NMR chemical shifts (Delta delta < 0.08 ppm) that decrease in the order Hortho > Hmeta > Hpara, the experimental O-methylation induced shifts in ortho-disubstituted phenols are largest for Hpara, Delta delta equals; 0.19 +/- 0.02 ppm (n = 11). The differences are due to different conformational behavior of the OH and OCH3 groups; while the ortho-disubstituted OH group remains planar in polyphenols due to hydrogen bonding and conjugative stabilization, the steric congestion in ortho-disubstituted anisoles outweighs the conjugative effects and forces the Ar-OCH3 torsion out of the ring plane, resulting in large stereoelectronic effects on the chemical shift of Hpara. Conformational searches and geometry optimizations for 3-16 at the B3LYP/6-31G** level, followed by B3LYP/6-311++G(2d,2p) calculations for all low-energy conformers, gave excellent correlation between computed and observed 1H NMR chemical shifts, including agreement between computed and observed chemical shift changes caused by O-methylation. The observed regularities can aid structure elucidation of partly O-methylated polyphenols, including many natural products and drugs, and are useful in connection with chemical shift predictions by desktop computer programs.     

The 1H and 13C nmr spectra of the “onium” salts of dithiacyclophanes

The ¹H and ¹³C nmr spectra of three cyclic sulphonium salts ol dithiacyclophanes have been recorded and compared with those of the open-chain analogue. The ¹H spectra indicate that methylation of the dithiacyclophanes gives a mixture of eonformational isorners with slightly different chemical shifts for the benzylic protons. The ¹³C spectra indicate that the smaller rings adopt an unsymmetrical conformation with respect to the aromatic ring but that in the larger ring studied, the aromatic carbon atoms are magnetically equivalent. The relevance of these results to the reactivity of the aromatic ring is discussed.     

Synthesis,structure and thermal rearrangement of tetramethyldisilane-bridged bis(cyclopentadienyl) diiron complexes with a phosphite or phosphine ligand substitution

Photolysis of tetramethyldisilane-bridged bis(cyclopentadienyl) tetracarbonyl di-iron in the presence of phosphite or phosphine ligand afforded the corresponding Fe–Fe bond complexes with one carbonyl replaced by a phosphite or phosphine ligand: [(Me₂SiSiMe₂)Cp₂Fe₂(CO)(PR₃)(μ-CO)₂] (R=OPh, 1; OEt, 2; Ph, 3). When these complexes were heated in refluxing xylene, they become rearranged to the corresponding products [(Me₂SiCpFe)₂(CO)₃(PR₃)] (R=OPh, 4; OEt, 5; Ph, 6). It was found that, after phosphite or phosphine ligand substitution, the rearrangement became facile. The molecular structures of 1–6 were characterized by IR, ¹H NMR spectra and elemental analyses. The crystal structures of 1 and 4 were determined by X-ray diffraction analysis.     

1H chemical shifts in NMR. Part 27: proton chemical shifts in sulfoxides and sulfones and the magnetic anisotropy, electric field and steric effects of the SO bond

The (1)H chemical shifts of a series of sulfoxide and sulfone compounds in CDCl(3) solvent were obtained from experiment and the literature. These included dialkyl sulfoxides and sulfones (R(2)SO/R(2)SO(2), R = Me, Et, Pr, n-Bu), the cyclic compounds tetramethylene sulfoxide/sulfone, pentamethylene sulfoxide/sulfone and the aromatic compounds p-tolylmethylsulfoxide, dibenzothiopheneoxide/dioxide, E-9-phenanthrylmethylsulfoxide and (E) (Z)-1-methylsulfinyl-2-methylnaphthalene. The spectra of the pentamethylene SO and SO(2) compounds were obtained at -70 degrees C to obtain the spectra from the separate conformers (SO) and from the noninverting ring (SO(2)). This allowed the determination of the substituent chemical shifts (SCS) of the SO and SO(2) functional groups, which were analyzed in terms of the SO bond electric field, magnetic anisotropy and steric effect for long-range protons together with a model (CHARGE8d) for the calculation of the two and three bond effects. After parameterization, the overall root mean square (RMS) error (observed-calculated) for a dataset of 354 (1)H chemical shifts was 0.11 ppm. The anisotropy of the SO bond was found to be very small, supporting the dominant single bond S(+)--O(-) character of this bond.     

FT-IR and FT-Raman study of hydrogen bonding in p-alkylcalix[8]arenes

The FTIR and FT Raman spectra of p-alkylcalix[8]arenes (alkyl = tert-butyl, isononyl) were recorded. Analysis of IR spectra showed that the cyclic cooperative intramolecular hydrogen bond is realized in calix[8]arene. It was found that the strength of the cyclic cooperative intramolecular hydrogen bond in the series of alkyl derivatives of calix[8]arenes depends very little on the replacement of the p-tert-butyl groups by the more bulky isononyl group. From our data follows that the orientation of aromatic fragments in calixarene molecules depends on the type of alkyl substituent.An analysis of the changes in the IR spectra with heating and dissolution shows that the conformation of the “pleated-loop” is retained in p-tert-butylcalix[8]arene. It turned out that the intramolecular hydrogen bond is a “probe” of the conformation of calixarene molecules and IR spectroscopy is a unique method that allows one to follow the slightest nuances of changes in the H-bound system of these supermolecules.     

Proton affinities of phenylalkylamines by the kinetic method

The kinetic method was used to determine the proton affinities of phenylalkylamines of general formula R¹R²C₆H₃CHR³(CH₂)_nNR⁴R⁵ where R¹ = H or OH; R² = H, F, NO₂, OH or OCH₃; R³ = H or OH; R⁴ and R⁵ = H and/or CH₃; n = 1−3. Amines were used as reference bases and the proton affinities of the phenylalkylamines were bracketed by a pair of reference bases that give rise, in the MIKE spectra of the heterodimer, to more or less intense signals than the compound under study. The influence of the aliphatic chain length and of the substituents on the aromatic ring, on the proton affinities of the phenylalkylamines is presented and discussed. The formation of an hydrogen bond between the amino group and the aromatic ring is proposed to explain the results obtained.     

Synthesis and Properties of Exo-Phosphorylated Benzocrown-Ethers

Abstract

The crown ethers 1,2, containing exocyclic phosphorus groups, were obtained¹ by the interaction of, bromo-, iodo-, and sulpamidoderivatives of mono- and dibenzocrown ethers with esters of trivalent phosphoric acids, alkenylphos-phonates and phosphorus pentachloride in presence of metal catalysts. On the basis of these compounds the crown ethers with various substitutes at phosphorus atom (including the polymeric ones) were synthesized. Further reaction of the crown ether 1 (X = “-” R = Ph, R′ = H) with glycol dichlo-rides gave first phosphorus-containing bis-crown ethers 3.     

Etude conformationnelle,par rmn du 13C,d'ethers d'enol renfermant un noyau aromatique

Two series of aromatic enol ethers deriving from 1-methoxy-1-phenyl ethylene and from 1-methoxy-1-phenyl 2-methyl propene have been studied by ¹³C NMR. Comparisons between the chemical shifts of these enol ethers and those of styrene on the one hand, and aliphatic enol ethers on the other, led us to conclude that the non-coplanarity of the phenyl ring with the double bond and/or the non-coplanarity of the OCH₃ group with the same double bond play a prominent role in determining the chemical shift values of the ethylenic carbons. Para-substitution on the phenyl ring induces chemical shift variation not only in the aromatic moiety itself but also in the ethylene part of the molecule. The significance of the observed Hammett correlation is discussed.     

联苯型[11], [14]和[17]环系氮杂支链套索冠醚的合成

以碳酸钾为缩合剂, 2,2'-二羟基联苯分别与二对甲苯磺酸酯Ⅱa~c, Ⅳb,Ⅵb反应合成尚未见文献报道的联苯型单氮杂冠醚(1~3), 二氮杂冠醚9和11。3,9和11分别用氢溴酸去对甲苯磺酰基得到亚胺型氮杂冠醚4, 10和12。4与溴代烃RBr(R=-(CH2)3CH3, -CH2CH=CH2, -(CH2)7CH3, -(CH2)2O(CH2)2OC4H9)反应分别合成[11]环系氮支套索冠醚(5~8), 12与正溴丁烷反应合成[17]环系氮支冠醚13。以上13种化合物皆为新型未见文献报道, 其结构皆经元素分析, IR, ^1H NMR,MS确证。     

Spiro-compounds,synthesis and catalytic dehydrogenation of substituted spiro[5,5] undecanes

Catalytic dehydrogenation of 1-propyl-8,9-benzospiro[5,5]undecane-7-ol (5: R = H), and 1-propyl-3′-methyl-8,9-benzospiro[5,5]undecane-7-ol (5: R = Me) has been carried out to study the effect of a bulky alkyl group on the ring in the ring transformation of the spiro[5,5]undecane system. The catalytic dehydrogenation of the spiro-compound 5(R = H) gave phenanthrene and 1-ethylpyrene (minor product) and spiro compound 5(R = Me) gave only 3-methylphenanthrene. For the synthesis of 5 (R = H or Me), the anhydride (1) of 1-carboxy-2-propylcyclohexane-1-acetic acid was condensed with benzene and toluene to give 2 (R = H or Me) which was reduced catalytically to 3(R = H or Me). Intramolecular acylation of 3(R = H or Me) gave the spiroketone (4: R = H or Me) which was reduced to 5(R = H or Me).     

17O NMR Investigation of cyclic aromatic ethers

A linear relationship between the C-O-C angle and the molecular dihedral angle in a series of phenoxathi-ins and azaphenoxathiins is reported. ¹⁷O nmr spectroscopic data (natural abundance in acetonitrile at 75°C) were obtained on eight cyclic aromatic ethers 1-8 , including phenoxathiins, and two model compounds, acyclic aromatic ethers 9 and 10. The chemical shifts of the cyclic aromatic ethers were very sensitive to structural variations and were dependent upon electonic and conformational effects; however, no quantitative relationship between ¹⁷O chemical shift and geometric parameters was found.     

Synthesis, characterizations and crystal structures of di-n-butyltin(IV) complexes with heteroatomic (N, O or S) acid

Two types of di-n-butyltin(IV) complexes {[ⁿBu₂Sn(O₂CR)]₂O}₂ · L 1-4 and ⁿBu₂Sn(O₂CR)₂Y 5-8 (when L=H₂O, R=2-pyrazine 1; L=0, R=2-pyrimidylthiomethylene 2, 1-naphthoxymethylene 3; L=C₆H₆, R=2-naphthoxymethylene 4; when Y=H₂O, R=2-pyrazine 5; Y=0, R=2-pyrimidylthiomethylene 6, 1-naphthoxymethylene 7, 2-naphthoxymethylene 8) have been prepared in 1:1 or 1:2 molar ratios by reactions of di-n-butyltin oxide with the heteroatomic (N, O or S) carboxylic acids. The complexes 1-8 are characterized by elemental, IR, ¹H and ¹³C NMR spectra. And except for complexes 6 and 7, the complexes 1-5 and 8 are also characterized by X-ray crystallography diffraction analyses, which reveal that the tin atom of complex 5 is seven-coordinated, while the complexes 1-4 and 8 are all hexa-coordinated. The nitrogen atom of the aromatic ring in complexes 1 and 5 participates in the interactions with the Sn atom.     

High‐Field NMR Spectroscopy Reveals Aromaticity‐Modulated Hydrogen Bonding in Heterocycles

From DNA base pairs to drug–receptor binding, hydrogen (H‐)bonding and aromaticity are common features of heterocycles. Herein, the interplay of these bonding aspects is explored. H‐bond strength modulation due to enhancement or disruption of aromaticity of heterocycles is experimentally revealed by comparing homodimer H‐bond energies of aromatic heterocycles with analogs that have the same H‐bonding moieties but lack cyclic π‐conjugation. NMR studies of dimerization in C₆D₆ find aromaticity‐modulated H‐bonding (AMHB) energy effects of approximately ±30 %, depending on whether they enhance or weaken aromatic delocalization. The attendant ring current perturbations expected from such modulation are confirmed by chemical shift changes in both observed ring C−H and calculated nucleus‐independent sites. In silico modeling confirms that AMHB effects outweigh those of hybridization or dipole–dipole interaction.     

Photochemische reaktionen—XXXIII: Molekular- und kristallstruktur eines photoprodukts aus gibberelun C

In connection with studies concerning the photochemistry of carbonyl gibberellins, the structure of a ring D seco photoproduct 1 obtained upon UV irradiation of gibberellin C has been established by X-ray analysis and the molecular packing determined. The lattice parameters are a=b=11.935 Å and c=31.717 Å; the space group is P4₃2₁2. The final discrepancy factor R was 0.063.     

13 C-NMR-untersuchungen an substituierten cycloalkenen : I. Trimethylsilylenolether

The ¹³C-NMR spectra of the cyclic silyenolethers 1a-i are discussed with regard to the electron density within the carbon ring skeleton, conformation of the trimethylsilyloxy substituent and configuration of the double bond in higher membered ringsystems.     

Polymerization of Cyclic Ethers

Abstract

In the present series of studies on the cationic polymerization of cyclic ethers, the reactivities of cyclic ethers were quantified and the effect of the catalyst upon the polymerization kinetics was revealed. These kinetic analyses were successfully performed by means of our “phenoxyl end-capping method”. The change of the reactivity by the ring size of the monomer was interestingly demonstrated. In addition, it is emphasized that the frequency factor as well as the activation energy influence the rate constant of propagation. As to the effect of catalyst upon the polymerization kinetics, the most important conclusion is that the rate constant of propagation changes very little according to the changes of the catalyst components. Variation of the conversion rate by a change of catalyst is due to differences in the rates of the initiation and the termination reactions.     

A comparative study of some lithium and hydrogen‐bonded complexes: Ab initio and QTAIM studies

The nature of the interactions of cyanide with lithium and hydrogen halides was investigated using ab initio calculations and topological analysis of electron density. The computed properties of the lithium‐bonded complexes RCN···LiX (R = H, F, Cl, Br, C?CH, CH?CH₂, CH₃, C₂H₅; X = Cl, Br) were compared with those of corresponding hydrogen‐bonded complexes RCN···HX. The results show that both types of intermolecular interactions are “closed‐shell” noncovalent interactions. The effect of substitution on the interaction energy and electron density at the bond critical points of the lithium and hydrogen bonding interactions is similar. In comparison, the interaction energies of lithium‐bonded complexes are more negative than those of hydrogen‐bonded counterparts. The electrostatic interaction plays a more important role in the lithium bond than in the hydrogen bond. On complex formation, the net charge and energy of the Li atom decrease and the atomic volume increases, while the net charge and energy of the H atom increase and the atomic volume decreases. © 2013 Wiley Periodicals, Inc.     

Rutaceous constituents—13: A biomimetic synthesis of acronycine

A biomimetic synthesis of the anti-tumor active alkaloid acronycine (7; R=R'=Me) has been obtained by cyclisationof 6-(2-methylaminobenzoyl)-5,7-dimethoxy-2.2-dimethylchromene (11 : R=R'=Me); isoacronycine (20; R=R'=Me) was also produced. In an analogous manner the aminochromene (11 ; R=H. R'=Me) gave a mixture of des-N-methylacronycinc (7; R=H, R$\text{=}\text{?}$Me) and des-N-methylisoacronycine (20; R=H, R'=Me). The aminochromenes were best synthesised by condensation of lithio-5,7-dimethoxy-2,2-irnethylchromene (22; R=Li) with N-methylisatoic anhydride (26) or with 2-methyl-3.1-benzoxazm-4-one (21).The relevance of this synthetic route to the biogenesis of acridone alkaloids is discussed.