Boat-chair conformational preference of exo, exo-9-oxobicyclo[3.3.1]nonane-2,4-dicarboxylic acid

The ¹H and ¹³C nmr spectra of $\text{exo}$, $\text{exo}$-9-oxobicyclo[3.3.1]nonane-2,4-dicarboxylic acid, 3, in DMSO-d₆ or alkaline D₂O, clearly show that it exists in a $\text{boat}$-$\text{chair}$-conformation with $\text{equatorial}$ carboxyl groups, thus being the first case of $\text{boat}$-$\text{chair}$ preference of a bicyclo[3.3.1] nonan-9-one due to the presence of $\text{exo}$,$\text{exo}$-2,4- substituents.     

Perfluoroalkyl derivatives of nitrogen. Part LI [1]. Reaction of the N-halogenobistrifluoromethylamines (CF3)2NX (X=Cl,Br) with norbornadiene

Reaction of the amines (CF₃)₂NX (X=Cl,Br) with norbornadiene either in solvent (CH₂Cl₂) at ?78 °C in the dark or in the vapour phase at 20 °C in daylight gives a mixture of 3-halogeno-5-($\text{NN}$-bistrifluoromethylamino)nortricyclene ($\text{exo}$, $\text{endo}$-and $\text{exo}$, $\text{exo}$-isomers) and $\text{exo}$-5-($\text{NN}$-bistrifluoromethylamino)- $\text{anti}$-7-halogenonorbornene in quantitative yield formed $\text{via}$ halonium ion addition to the diene. The reaction of the amine (CF₃)₂NBr in solvent Me₂O or Et₂O at ?78 °C in the dark gives the same products in low yield, together with 3-bromo-5-alkoxynortricyclene ($\text{exo}$, $\text{endo}$- and $\text{exo}$, $\text{exo}$-isomers) and the amine (CF₃)₂NR (R=Me, Et) in high yield.     

Stereoselective synthesis of (25R)-25,26-dihydroxy-23-oxovitamin D3 and its enzymatic conversion to (25R)-1α,25,26-trihydroxy-23-oxovitamin D3, a putative metabolite of vitamin D3

(25$\text{R}$)-25,26-Dihydroxy-23-oxovitamin D₃ was synthesized efficiently and stereoselectively, and it was converted enzymatically to (25$\text{R}$)-1α,25,26-trihydroxy-23-oxovitamin D₃, a putative metabolite of 1α,25-dihydroxyvitamin D₃. The spectral and chemical properties of (25$\text{R}$)-25,26-dihydroxy-23-oxovitamin D₃ and its 1α,hydroxylated derivative disagree with those reported for the isolated metabolite.     

Synthesis and chemistry of HC(SO2F)3 and cis- and trans(HO)2TeF4

HC(SO₂F)₃ has been prepared and characterized. It turned out to be a strong acid, comparable to mineral acids. In aqueous solution the salts of the type Cs⁺C(SO₂F)₃^? are formed. The anion, as found by crystal structure analysis contains planar CS₃ configuration.Quite in contrast to these findings HC(OSO₂F)₃ is not even soluble in water.Derivatives of HC(SO₂F)₃ have been prepared so far CH₃C(SO₂F)₃ FC(SO₂F)₃ ClC(SO₂F)₃ BrC(SO₂F)₃ JC(SO₂F)₃The heavier halogen derivatives ( Cl, Br, J ) are oxidizing agents (‘positive halogen’).A mixture of $\text{cis-}$ and $\text{trans-}$ (HO)₂TeF₄ is obtained if HOTeF₅ and Te(OH)₆ are melted together. The mixture of the isomeres have been transfered into the corresponding silylesters $\text{cis}$- and $\text{trans-}$ (R₃SiO)₂TeF₄, which could be separated by fractional crystallisation and distillation.Without conformational change the pure silylesters have been reacted back to pure $\text{cis}$- (HO)₂TeF₄ and $\text{trans}$- (HO)₂TeF₄ by means of anhydrous HF. Both $\text{cis-}$ and $\text{trans}$ (HO)₂TeF₄ have been reacted with ClF to give $\text{cis}$- and $\text{trans}$- (ClO)₂TeF₄, yellow liquids. The latter react with elemental bromine to the rather unstable $\text{cis-}$ and $\text{trans-}$ (BrO)TeF₄, red liquids.Starting with $\text{cis}$-(HO)₂TeF₄ and XeF₂ a polimer Xenon compound of the formula

All materials have been characterized by melting point and vapour pressure, 19 F - nmv spectroscopy, vibrational spectroscopy, and elemental analysis.     

Preparation of fluoroalkylated benzoheterocycles using F-2-methylpropene

Several benzoheterocyclic compounds carrying a CH(CF₃)₂ group were prepared by the reactions of $\text{F}$-2-methylpropene with ortho-bifunctional benzenes. The reactivity and reaction mode of $\text{F}$-2-methylpropene in these reactions were compared with those of $\text{F}$-propene.     

N-halogeno-compounds. Part II [1]. N.M.R. data for polyfluorocyclohexadienylideneamines obtained via N- chlorination of polyfluoroarylamines

N.m.r. parameters for nine (I-IX) $\text{N}$-chloropolyfluorocyclohexa-2,5-dienylideneamines are reported and discussed; the magnitudes of the FF-coupling constants fall into the following ranges:

$\text{J}$₁₂ 0-2.8; $\text{J}$₁₃, $\text{J}$₃₅ 6.0-6.8; $\text{J}$₁₄ <1; $\text{J}$₁₅ 0-2.6; $\text{J}$₂₃, $\text{J}$₃₄ 25.5-27.2; $\text{J}$₂₄ 0-6.0; $\text{J}$₂₅ 0-1.2; $\text{J}$₄₅ 5.4-9.8 Hz (I) X = Y = Z = F; (II) X = OMe, Y = Z = F; (III) X - CF₃, Y = Z = F; (IV) X = Ph, Y = Z = F; (V) X = Cl, Y = Z = F; (VI) X = Br, Y = Z = F; (VII) X = Y = F, Z = Cl; (VIII) X = Y = F, Z = Br; (IX) X = Z = F, Y = H. The spectra of $\text{N}$-methyl-4-chloropentafluorocyclohexa-2,5-dienyldeneamine have also been analysed. All the imines examined are configurationally stable at the nitrogen atom.     

Reversible nethide shifts in the 2-tert-butyl-2-adamantyl cation

Treatment of either 3-$\text{tert}$-butyl-2-adamantanol or 2-isopropenyl-2-methyladamantane with acid in the presence of a reducing agent (hydrogen iodide or tri-$\text{2}$-hexylsilane) yielded 2-$\text{tert}$-butyladamantane as the major or exclusive product. Both precursors gave the 2-$\text{tert}$- butyl-2-adamantyl cation at ?78°C in FSO₃H-SbF₅-SO₂ClF.     

Cis-trihetero-tris-σ-homobenzenes as tridentate ligands - X-ray crystal. Structure analyses of the Co(C6H9N3)2(NO3)3 and Ba(C6H6O3)4(ClO4)2-complexes

According to X-ray crystal structure analyses “cis-benzenetrisimine” ($\text{2}$) and “cis-benzenetrioxide” ($\text{1}$) act as tridentate ligands in their 2:1- and 4:1-complexes $\text{7}$ (Co(C₆H₉N₃)₂(NO₃)₃) and $\text{8}$ (Ba(C₆H₆O₃)₄(ClO₄)₂), resp. The latter is the rare example of an organic complex with the (approximate) T-symmetry.     

Perhalogenmethylmercapto-heterocyclen, (VII) [1] konkurrenzreaktionen elektronenarmer,substituierter aromaten um die halogenmethylmercapto- BZW. Chlorgruppe von Cl3-nFnCSCl in starken saeuren

Electron-deficient aromatics, such as 2,5-bis(trifluoromethylmercapto)thiophene ($\text{1a}$) or (trifluoromethylmercapto)benzene ($\text{8a}$), react with F₃CSCl in the presence of F₃CSO₃ as a catalyst to give mainly 3-chloro-2,5-bis(trifluoromethylmercapto)thiophen ($\text{3a}$) and 1-chloro-4- or 2-(trifluoromethylmercapto)benzene ($\text{10}$, respectively. This reaction competes with the one expected to result in 2,3,5-tris(trifluoromethylmercapto)thiophene ($\text{2a}$) and 1,4- and 1,2-bis(trifluoromethylmercapto)benzene ($\text{9}$,$\text{9′}$), respectively. Further reactions of deactivated aromatics with Cl_3-nF_nCSCl show that the chlorine substitution is in general catalysed by strong acids. Reaction mechanisms are proposed for both Substitutions. The Cl_3-nF_nCS group in aromatics exerts a -M-effect in the case of an attack of a positive ion, e.g. H^⊕, the well-known +M-effect in the case of reactions with positively polarized molecules, e.g. CF₃S^β+Cl^β-.     

Aroyl anion trapping reactions. A preliminary study of direct nucleophilic aroylation by means of low temperature, insitu (CH3)nC6H5nLi/CO Systems.

Results of studies of the $\text{in}$$\text{situ}$ nucleophilic aroylation of PhCO₂Me, Me₃CCO₂Me and Ph₂CO by several low temperature ArLi/CO systems (Ar =C₆H₅, p-CH₃C₆H₄, $\text{o}$-CH₃C₆H₄, 2,6-(CH₃)₂C₆H₃ and 2,4,6-(CH₃)₃C₆H₂) are reported. The experiments with C₆H₅Li were unsuccessful and the best results were obtained with 2,6-(CH₃)₂-C₆H₃Li.     

Conformation,in solution,of c-4-t-butyl-1-phenyl-r-1-(N-piperidyl)cyclohexane hydrochloride. The conformational energy of t-butyl

Although the hydrochloride of $\text{c}$-4-$\text{t}$-butyl-1-phenyl-$\text{c}$-1-(N-piperidyl)cyclohexane crystallizes in the conformation with axial $\text{t}$-butyl, it exists as an almost equimolar mixture of the two chair conformers in CD₂ Cl₂ solution. The position of equilibrium allows one to calculate ΔG°_{$\text{t}$-Bu} as ?4.9 kcal/mol.     

Heat capacity and thermodynamic properties of ramsdellite,Li2Ti3O7, and spinel,Li43Ti53O4

The heat capacity and heat content Li_{$\text{4}\text{3}$}Ti_{$\text{5}\text{3}$}O₄ and Li₂Ti₃O₇ have been measured in the temperature range 198—960 K. The lattice and dilation contributions to the heat capacity have been estimated. The standard thermodynamic functions and the high temperature enthalpy and entropy have been derived. The lattice heat capacity of Li_{$\text{4}\text{3}$}Ti_{$\text{5}\text{3}$}O₄ spinel appears to be consistent with the phonon model put forward by Grimes.     

Peptides containing β-turns I-- cyclo-(gly-l-cys-gly)3 triply bridged by 1,3,5-tris-(thiomethyl)benzene

Reaction of $\text{cyclo}$-(Gly-$\text{L}$-Cys-Gly)₃ with 1,3,5-$\text{tris}$-bromomethylbenzene yields a $\text{tris}$ thioether of the cyclic nonapeptide in 28% yield. Both ¹H and ¹³C NMR spectra are consistent with a molecule of 3-fold symmetry; the temperature dependences of chemical shifts of the amide hydrogens are consistent with a structure composed of three β-turns.     

The octant rule. XIV. synthesis and circular dichroism of α-exo and endo-deuteriobicyclo[3.2.1]octan-3-one and 6,6-dimethybicyclo[3.1.1]heptan-3-one

(1R,5S)-2S-Deuteriobicyclo[3.2.1]octan-3-one ($\text{1}$) and (1R,5S)-2R-Deuteriobicyclo[3.2.1]octan-3-one ($\text{2}$), prepared by diazomethane ring enlargement of (1S,4R)-2(exo)-deuteriobicyclo-[2.2.1] heptan-2-one and (1S,4R)-2(endo)-deuteriobicyclo[2.2.1]heptan-2-one respectively, both gave (?) n-π^* circular dichroism (CD) Cotton effects, Δε^max₂₉₄ = ?0.05 and Δε^max₂₉₄=?0.1, respectively, in hydrocarbon solvent. (1S,5R)-2S-Deuterio-6,6-diaethylbicyclo[3.1.1] heptan-3-one ($\text{3}$) and (1S,5R)-2R-deuterio-6,6-dimethylbicyclo[3.1.1] heptan-3-one ($\text{4}$), prepared from (-) myrtenal, both exhibited extraordinary vibrational fine structure for the n-π^* CD transitions observed in hydrocarbon solvent and oppositely?signed CEs, Δε^max₂₈₂=?0.01 and Δε^max₂₇₉=+0.01 respectively in CF₃CH₂OH solvent.     

The chemical oxidation and electronic spectra of the complexes trans-[M(CNR)2(Ph2PCH2CH2PPh2)2] (M = Mo or W)

Oxidation of the complexes $\text{trans}$-[M(CNR)₂(dppe)₂] (A) (M = Mo or W; R = Me, Bu^t or CH₃C₆H₄-$\text{4}$; dppe = Ph₂PCH₂CH₂PPh₂) with diiodine or silver (I) salts gives the paramagnetic cations $\text{trans}$-[M(CNR)₂(dppe)₂]⁺, (M = Mo, R = CH₃C₆H₄-$\text{4}$; M = W, R = Bu^t) and $\text{trans}$-[M(CNR)₂(dppe)₂]²⁺ (M = Mo, R = Me or CH₃C₆H₄-$\text{4}$; M = W, R = Me or Bu^t). Mixtures of products are generally produced when dichlorine or dibromine are the oxidising agents, however pure salts, the seven-coordinate complex cations [MX(CNC₆H₄CH₃-$\text{4}$)₂(dppe)₂]⁺ (B, X = Cl or Br) have been isolated. A simple molecular orbital scheme is proposed for complexes (A) and used to discuss their electronic spectra and their oxidation.     

Anomalies in the asymmetric hydroboration of olefins with the 11 adduct of (+)-α-pinene and BH3 · THF

The hydroboration of cis-2-butene and cis-3-hexene with pure diisopinocampheylborane (IPC₂BH) and monoisopinocampheylborane (IPCBH₂), both prepared from (+)-α-pinene, were studied. In contrast to IPC₂BH, which yielded R-(?)-2-butanol and R-(?)-3-hexanol in 98.4 and 94.5% optical purities, IPCBH₂ yielded S-(+)-2-butanol and S-(+)-3-hexanol in 23.6 and 19.7% optical purifies respectively. PMR examination of the methanolyzed products were utilized to establish the species present in the freshly prepared and aged $\text{1}\text{1}$ adduct from (+)-α-pinene and BH₃ · THF. The results confirm the interpretation previously advanced for the major differences realized in asymmetric hydroboration with the fresh and aged $\text{1}\text{1}$ adducts.     

Halogen cleavage reactions of cis-(threo-PhCHDCHD)Mn(CO)4PEt3

Halogen cleavage reactions of $\text{cis}$-($\text{threo}$-PhCHDCHD)Mn(CO)₄, PEt₃ ($\text{3}$) are studied in detail and are found to proceed either predominantly with retention or inversion, or non-stereospecifically, depending on reaction conditions. Reaction mechanisms involving S_E2 (inversion), S_E2 (retention) and S_E (oxidative) processes are proposed, demonstrating that halogen cleavage reactions of $\text{3}$ straddle the mechanistic borderline between electrophilic substitution and oxidation processes of transition metal alkyl compounds.     

Reactions of F-propene and its dimer with sodium dialkyldithiocarbamate

Sodium dialkyldithiocarbamates readily attacked $\text{F}$-propene to give S-(1,1,2,3,3,3-hexafluoropropyl)-N,N-dialkyldithiocarbamates, CF₃CHFCF₂SC(S)-NR₂, and $\text{Z}$ and $\text{E}$-S-(1,2,3,3,3-pentafluoropropenyl)-N,N-dialkyldithiocarbamates, CF₃CFCFSC(S)NR₂. The pyrolysis of the former compound quantitatively gave the dialkylthiocarbamoyl fluorine, R₂NC(S)F, while the latter compound and sodium tetraphenylborate formed the corresponding 1,3-dithiolan-2-ylium tetraphenylborate. $\text{F}$-2-Methyl-2-pentene also reacted with sodium dialkyldithiocarbamate to give (CF₃)₂CHC[SC(S)NR₂]CFCF₃. The mechanism of this reaction is supposed to involve a 1,4-RSF-elimination.     

C26-C29 triaromatic steroid derivatives in sediments and petroleums.

The C₂₆-C₂₉ cyclopentenophenanthrenes $\text{1}$ - $\text{3}$ have been identified as widespread constituents of sediments and petroleums. They are long term degradation products of sterols in the subsurface     

Action of tert-butyl azidoformate on the conjugate bases of 1,2,3,4-tetrahydro-9H-carbazole and other indole derivatives

tert-Butyl azidoformate ($\text{2}$) reacts with the conjugate bases of $\text{3a}$, $\text{7a}$, $\text{9}$ (R¹ = R² = CH₃), and $\text{9}$ (R¹ = CH₃, R² = H) to give products [$\text{4}$, $\text{8}$, $\text{12}$, and $\text{14}$, respectively] in addition to the expected N-(tert-butoxycarbonyl)indole derivatives.