Reaction of N-substituted <Emphasis Type="Italic">exo</Emphasis>-2-hydroxy-5-oxo-4-oxatricyclo[4.2.1.0<Superscript>3,7</Superscript>]nonane-<Emphasis Type="Italic">endo</Emphasis>-9-carboxamides with acetic acid

Acylation of N-substituted exo-2-hydroxy-5-oxo-4-oxatricyclo[4.2.1.0^3,7]nonane-endo-9-carboxamides on heating in boiling glacial acetic acid gave the corresponding trans-diacetoxy imides of the norbornane series. The effect of the reaction time on the product composition was studied in the reaction with exo-2-hydroxy-N-(4-methylphenyl)-5-oxo-4-oxatricyclo[4.2.1.0^3,7]nonane-endo-9-carboxamide. The structure of the resulting norbornane-2,3-dicarboximides was confirmed by IR, ¹H NMR, and mass spectra, and the structure of N-(2,5-dimethylphenyl)-exo-2,endo-3-diacetoxybicyclo[2.2.1]heptan-endo-5,endo-6-dicarboximide was additionally proved by X-ray analysis.     

Amido acids of norbornene series in reactions with sulfonyl azides

In reaction of amido acids from the norbornene series with arenesunfonyl azides alongside the expected N,N-dialkyl-5-oxo-exo-2-arylsulfonylamino-4-oxatricyclo[4.2.1.0^3,7]nonane-endo-9-carboxamides (oxabrendanones) the formation of zwitter-ions with a structure of 5-(N,N-dialkyliminio)-exo-2-arylsulfonylamino-4-oxatricyclo[4.2.1.0^3,7]nonane-endo-9-carboxylates came as a surprise. The structure of compounds obtained was confirmed by the analysis of their IR and ¹H NMR spectra. The molecular structure of one among the zwitterions was established by XRD analysis.     

Photochemical Synthesis and Some Reactions of 7-Oxa-and 7-Thiatricyclo[3.2.1.03,6]octan-2-ones

Irradiation (λ = 350 nm) of newly synthesized 2-acetyl- or 2-methyl-2-(alk-2-enyl)furan-3(2H)-ones 1 and 2-acetyl- or 2-methyl-2-(prop-2-enyl)thiophen-3(2H)-ones 2 affords the corresponding 1-acetyl- or 1-methyl-substituted 7-oxa- and 7-thiatricyclo[3.2.1.0^3,6]octan-2-ones 10 and 11 , respectively, via regioselective intramolecular [2 + 2] photocycloaddition in 65–95% yield (Scheme 2). The 1-acetyl-substituted O-derivatives 10b and 10c undergo ring opening on treatment with MeONa in MeOH at–78° to afford stereoselectively methyl 3-exo-acetyl-2-oxabicyclo[3.2.0]heptane-7-endo-carboxylates 12b and 12c , respectively, while a 2:1 diastereoisomeric mixture of methyl 3-acetyl-2-thiabicyclo[3.2.0]heptane-7-endo-carboxylates 13 and 14 is obtained from the corresponding S-derivative 11b . The outcome of the Huang-Minlon reduction of the 1-methyl-substituted ketones 10a and 11a is again influenced by the heteroatom in the tricycle. While 1-methyl-7-oxatricyclo[3.2.1.0^3,6]-octane ( 15 ) is the only product from the corresponding oxatricyclooctanone 10a , a 1:2 mixture of 1-methyl-7-thiatricyclo[3.2.1.0^3,6]-octane ( 16 ) and 3-methylbicyclo[3.1.1]hept-2-ene-6-endo-thiol ( 17 ) is obtained from the analogous S-compound 11a , both products stemming from a common carbanion precursor.     

13C-NMR-Spektren von Tetracyclo[4.1.0.02,4.03,5]heptanen,Tetracyclo[5.1.0.02,4.03,5]octanen und Tricyclo[4.1.0.02,7]hept-3-enen. Ungewöhnliche δ- und γ-Substituenteneffekte

Carbon-13 NMR spectroscopic data of eleven tetracyclo[4.1.0.0^2,4.0^3,5]heptanes, two tetracyclo-[5.1.0.0^2,4.0^3,5]octanes and twelve tricyclo[4.1.0.0^2,7]hept-3-enes are reported. In the tetracycloheptanes, halogens located at the 7-position cause large δ substituent effects. endo-Halogens shift the C-4 signal to lower field by about 6 ppm, while exo-haolgens produce upfield shifts of the C-3 signal, which are dependent on the nature of the halogen and reach a maximum of 9.1 ppm in the case of fluorine. An orbital model is proposed to explain the δ upfield shifts. The compounds containing fluorine reveal a connection between the δ substituent effects and the corresponding ¹³C? ¹⁹F coupling constants. Substituents in the 5 position of tricycloheptenes are γ-substituents of C-1, C-3 and C-7 and produce downfield shifts of the absorptions of these nuclei. Their dependence on the nature of the substituent follows approximately those in 1-substituted adamentanes; in the case of C-7, however, their magnitude by far exceeds the adamantane values, bromine (15.5 ppm) being most effective.     

Ionization and appearance potentials in organic chemistry. I—energetic aspects of the mass spectra of stereoisomeric 4-substituted N-alkyl-2-methyldecahydroquinol-4-ols

The ionization potentials for the stereoisomers of trans-fused 1,2-dimethyl- and 1-ethyl-2-methyl-4-R-decahydroquinol-4-ols (R?C?CH, CH?CH₂ or C₂H₅) and the appearance potentials for the [M–CH₃]⁺ and [M–C₂H₅]⁺ ions (loss of 2-CH₃ and 4-C₂H₅ groups potential, respectively) were measured by using the electron impact method. The ionization and appearance potential for [M–CH₃]⁺ are always lower for the isomers with the axial 2-CH₃ group. For the C-2 epimers, the difference between the appearance potentials for the [M–CH₃]⁺ ion values is likely to be equal to the enthalpy differences between the ground states of the epimers and the dissociation energy differences between the axial and equatorial C₂–CH₃ bonds. The appearance potentials for [M–C₂H₅]⁺ for the C-4 epimers possessing the 4-C₂H₅ group were very similar. At the same time, the appearance potentials for the [M–CH₃]⁺ ions were lower for less stable epimers which had an axial 4-C₂H₅ group.     

Reactive species from aromatics and oxa-di-π-methane rearrangement: a stereoselective synthesis of (±)-hirsutene from salicyl alcohol

A total synthesis of hirsutene, a triquinane sesquiterpene, from salicyl alcohol is reported. Oxidation of salicyl alcohol in the presence of cyclopentadiene gave 9-spiroepoxy-endo-tricyclo[5.2.2.0^2,6]undeca-4,10-dien-8-one which was elaborated to the 3-hydroxy-2-methyl-endo-tricyclo[5.2.2.0^2,6]undeca-10-en-8-one containing major structural and functional features of hirsutene. Photochemical sigmatropic 1,2-acyl shift in 3-hydroxy-2-methyl-endo-tricyclo[5.2.2.0^2,6]undeca-10-en-8-one followed by radical induced cleavage of peripheral cyclopropane bond, olefination and Simmon-Smith reaction furnished 11-hydroxy-1-methyl-4-spirocyclopropanetricyclo[6.3.0.0^2,6]undecane that upon treatment with hydrogen on PtO₂ and PCC oxidation gave 1,4,4-trimethyltricyclo[6.3.0.0^2,6]undecan-11-one, a known precursor. Wittig methylenation on this precursor gave hirsutene.     

Synthetic transformations of isoquinoline alkaloids. Synthesis of 1-halo derivatives of <Emphasis Type="Italic">endo</Emphasis>-ethenotetrahydrothebaine and their behavior in the heck reaction

Bromination of endo-ethenotetrahydrothebaine derivatives having a pyrrolidine ring fused at the C⁷-C⁸ bond, namely 1′-substituted 4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morphinan-2′,5′-diones, 1′-aryl-4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morphinans, and 4,5α-epoxy-6α,14-etheno-2′α-hydroxy-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morpphinan-5′-one, with molecular bromine in formic acid smoothly afforded the corresponding 1-bromo derivatives. Iodination of 4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]-4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]-morphinan-2′,5′-dione with iodine(I) chloride gave 4,5α-epoxy-6α,14-etheno-1-iodo-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morphinan-2′,5′-dione. The resulting 1-halo derivatives were brought into the Heck reaction with acrylic acid esters to obtain 1-[(E)-2-(alkoxycarbonyl)ethenyl]-substituted compounds. Demethylation of the 6-methoxy group in 1-bromo-endo-ethenotetrahydrothebaines was accomplished using boron(III) bromide in chloroform.     

Reductive Radical Cyclisations of Bromo Acetals and (Bromomethyl)silyl Ethers of Terpenoid Alcohols

The tin hydride promoted and the reductive vitamin B₁₂ catalysed radical cyclisation of mixed 2-bromo-acetaldehyde acetals and of (2-bromomethyl)dimethylsilyl ethers of allylic terpenoid alcohols has been investigated: 3-oxadeca-5,9-dien-l-yl radicals undergo 5-‘exo’ cyclisation to oxolanes (Scheme 4), 3-oxa-2-siladeca-5,9-dien-1-yl radicals sequential 6-‘endo’→5-‘exo’ tandem cyclisation to cis-3-oxa-4-silabicyclo[4.3.0]nonanes (Scheme 5), and 3-oxa-2-silatetradeca-5,9,13-trien-l-yl radicals sequential 6-‘endo’→6-‘endo’→5-‘exo’ triple cyclisation to trans-transoid-trans- 12-oxa-11-silatricyclo[7.4.0.0^2,6] tridecanes (Scheme 6).     

Synthesis of 2,6-dioxatricyclo[3.3.1.0]nonanes by intramolecular haloetherification and/or transannular hydroxycyclization of alkenes in [4+3]-cycloadducts

The synthesis of new difunctionalized 2,6-dioxatricyclo[3.3.1.0^3,7]nonanes is described. This type of structure is an interesting synthetic building block for potential bioactive molecules and it was prepared from 8-oxabicyclo[3.2.1]oct-6-en-3-one having a NHBoc function on C-1. This precursor was obtained by a [4+3] cycloaddition reaction of 2-tert-butoxycarbonylaminofuran and the oxyallyl cation generated in situ from 2,4-dibromo-3-pentanone. Reduction of the carbonyl group at C-3 was accomplished in high yield and stereoselective manner to afford the corresponding axial alcohol at C-3 as a major product. Further intramolecular haloetherification of this type of alcohols with NBS and I(py)2BF₄ led to the corresponding bromo and iodo-derivatives at C-8 of the 2,6-dioxatricyclo[3.3.1.0^3,7]nonane framework, in high yield. Epoxidation of 8-oxabicyclo[3.2.1]oct-6-en-3-ol followed by treatment with NaCN, NaN₃, and/or NaOH in MeOH afforded 8-hydroxy-2,6-dioxatricyclo[3.3.1.0^3,7]nonanes in high yield via a transannular hydroxycyclization mediated by a base and through an alkoxide intermediate. The new 2,6-dioxatricyclo[3.3.1.0^3,7]nonanes were tested for biological activity against HIV-1 virus and MT-4 lymphoid cell line, showing a low anti-HIV activity and a high degree of cytotoxicity.     

The epimeric 9‐oxobicyclo[3.3.1]nonane‐3‐carboxylic acids: hydrogen‐bonding patterns of the endo acid and the lactol of the exo acid

The two δ‐keto carboxylic acids of the title, both C₁₀H₁₄O₃, are epimeric at the site of carboxyl attachment. The endo (3α) epimer, (I), has its keto‐acid ring in a boat conformation, with the tilt of the carboxyl group creating conformational chirality. The mol­ecules form hydrogen bonds by centrosymmetric pairing of carboxyl groups across the corners of the chosen cell [O⃛O = 2.671 (2) Å and O—H⃛O = 179 (2)°]. Two close intermolecular C—H⃛O contacts exist for the ketone. The exo (3β) epimer exists in the closed ring–chain tautomeric form as the lactol, 8‐hydroxy‐9‐oxatri­cyclo­[5.3.1.0^3,8]­undecan‐10‐one, (II). The mol­ecules have conformational chirality, and the hydrogen‐bonding scheme involves intermolecular hydroxyl‐to‐carbonyl chains of mol­ecules screw‐related in b [O⃛O = 2.741 (2) Å and O—H⃛O = 177 (2)°].     

Mass spectrometric decomposition processes of 2-methyl-1-hexene

Unimolecular decompositions of 2-methyl-1-hexene and several labelled analogues were studied following 70 eV electron impact (normal and metastable spectra) and field ionization (field ionization kinetic measurements). Molecules labelled with ¹³C in the 1-position and the methyl position were found to behave essentially identically. This is attributed to rapid transfer of a hydrogen atom mainly from C-5 to C-1 (γ-hydrogen shift). Loss of ethene, propene or propenyl do not involve loss of the methyl carbon or C-1. All three reactions are better than 90% specific in this respect under all conditions studied. At shorter times, C₃H₆ loss is the dominant reaction, while at longer times C₂H₆ loss accounts for >90% of the ion current. It is proposed that at least two distinct pathways for C₂H₄ loss operate in linear 1-alkenes, one of which (loss of carbons 1 and 2) is blocked by a 2-methyl substituent. The [C₆H₁₁]^+˙ and [C₅H₁₀]^+˙ ions formed from ¹³C labelled 2-methyl-1-hexenes fragment in an essentially statistical fashion.     

Lactonization of epoxyendic anhydride in reactions with amines

Reactions of exo-5,6-epoxybicyclo[2.2.1]hept-5-ene-endo-2,endo-3-dicarboxylic anhydride (epoxyendic anhydride) with acyclic, aromatic, heteroaromatic, and nonaromatic heterocyclic amines afforded the corresponding heterocyclization products, substituted exo-2-hydroxy-5-oxo-4-oxatricyclo[4.2.1.0^3,7]nonane-endo-9-carboxamides (oxabrendanes), whose structure was confirmed by the IR and ¹H and ¹³C NMR (including two-dimensional) spectra. Other approaches to the tricyclic compounds were also examined, in particular via reactions of organic peroxy acids with amido acids obtained by aminolysis of endic anhydride.     

Adducts of Tricyclo[4.1.0.0<Superscript>2,7</Superscript>]heptane hydrocarbons with methane- and Halomethanesulfonyl Thiocyanates and their transformations in the presence of bases (nucleophiles)

1-R-Tricyclo[4.1.0.0^2,7]heptanes (R = H, Me, Ph) take up methane- and halomethanesulfonyl thiocyanates XCH₂SO₂SCN (X = H, Cl, Br) at the central C¹–C⁷ bond in benzene at 20°C with high anti-selectivity to give bicyclo[3.1.1]heptane derivatives with the 7-endo-oriented sulfonyl group and the thiocyanato group in the geminal position with respect to the R substituent. The syn-adducts lose HSCN molecule by the action of potassium tert-butoxide in THF at 0°C or on heating in boiling aqueous dioxane containing NaOH with formation of 1-(X-methylsulfonyl)tricyclo[4.1.0.0^2,7]heptanes. Under analogous conditions the anti-adducts (X = Me) are converted into 1,2-bis(7-syn-methylsulfonyl-6-endo-R-bicyclo[3.1.1]hept-6-exo-yl)disulfanes. The anti-adduct derived from unsubstituted tricyclo[4.1.0.0^2,7]heptane and MeSO₂SCN reacted with methyllithium or phenylmagnesium bromide to produce 7-anti-methyl(phenyl)sulfanyl-6-endo-methylsulfonylbicyclo-[3.1.1]heptanes which were also obtained by photochemical addition of MeSO₂SMe(or Ph) to tricyclo-[4.1.0.0^2,7]heptane. Geometric parameters of radical intermediates in the sulfonylation of 1-R-tricyclo-[4.1.0.0^2,7]heptanes were optimized ab initio using 6-31G basis set.     

exo/endo-Selectivity in the Reaction of ‘Bare’ FeO+ with Bicyclo[2.2.1]heptane (Norbornane)

‘Bare’ FeO⁺ reacts in the gas phase with norbornane with collision efficiency, and the most prominent cationic products correspond to [FeC₅H₆]⁺ (32%), [FeC₇H₈]⁺ (19%), [FeC₃H₆O]⁺ (19%) and [FeC₆H₆]⁺ (14%), which are structurally characterized by ligand exchange as well as collision-induced dissociation experiments. Circumstantial evidence is provided which indicates that the complexes [FeC₅H₆]⁺, [FeC₇H₈]⁺, and [FeC₆H₆]⁺ originate from an Fe(norbornene)⁺ intermediate which itself is formed by elimination of H₂O from the [FeO(norbornane)]⁺ encounter complex. Although the reactions are preceded and/or accompanied by partial H/D exchange, the isotope distribution in the productions clearly points to a preferential endo-attack of bare FeO⁺, with an endo/exo-ratio of ca. 10.3 and kinetic isotope effects k_H/k_D for the endo-abstraction of 2.4 and of 7.7 for approaching an exo-C? H bond. The preferred endo-approach of bicyclo[2.2.1]heptane by ‘bare’ FeO⁺ is in distinct contrast to the P-450-mediated or the iron(III)porphyrin-catalyzed hydroxylation of this substrate which favor reactions at the exo-face.     

Photochemische Reaktionen 42. Mitteilung [1]. Photoisomerisierung von α, β-Epoxyketonen II Der sterische Verlauf der Umlagerung von 3-Oxo-4, 5-oxido-Steroiden

The photorearrangement previously described [3] of saturated and Δ¹-unsaturated 3-oxo-4,5-epoxy-10β-steroids to 3,5-dioxo-10(5 →4)-abeo compounds proceeds most likely via a radical 1,2-alkyl shift (Chart 1). The similar rearrangements of the related 10α-epoxyketone 10 and the 4-methyl-epoxyketones 13 , 15 , 16 , 20 and 21 to the corresponding 3,5-diketones occurred without epimerization at the migrating carbon atom (C-10) and the site of substitution (C-4) (Chart 3). The stereochemical control of the rearrangement is in agreement with the earlier proposed mechanism of a concerted alkyl radical shift in these alicyclic systems.     

Photochemische Reaktionen. 52. Mitteilung [1]. Zur Photochemie von α,β-ungesättigten cyclischen Ketonen: Spezifische Reaktionen der n,π*- und π,π*-Triplettzustände von O-Acetyl-testosteron und 10-Methyl-Δ1,9-octalon-(2)

The photochemistry of the conjugated cyclohexenones O-acetyl testosterone ( 1 ) and 10-methyl-Δ^1,9-octalone-(2) ( 24 ) has been investigated in detail. The choice of reaction paths of both ketones depends strongly on the solvent used. In t-butanol, a photostationary equilibrium 1 ? 3 is reached which is depleted solely by the parallel rearrangement 1 → 5 (Chart 1; for earlier results on these reactions see [2a] [6] [7]). In benzene, double bond shift 1 → 16 (Chart 3) occurs instead, which is due to hydrogen abstraction from a ground-state ketone by the oxygen of an excited ketone as the primary photochemical process. In toluene, the major reaction is solvent incorporation ( 1 → 17 , Chart 4) through hydrogen addition to the β-carbon of the enone, accompanied by double bond shift and formation of saturated dihydroketone as the minor reactions. Contrary in part to an earlier report [19], the photochemical transformation of the bicyclic enoné 24 exhibit a similar solvent dependence. The corresponding products 25 – 29 are summarized in Chart 5 and Table 1. Sensitization and quenching experiments established the triplet nature of the above reactions of 1 and 24 . Based on STERN -VOLMER analyses of the quenching data (cf. Figures 2, 4–8, and Table 3), rearrangement, double bond reduction and toluene addition are attributed to one triplet state of the enones which is assigned tentatively as ³(π, π*) state, and the double bond shift is attributed to another triplet assigned as ³(n, π*) state (cf. Figure 9). The stereospecific rearrangement of the 1α-deuterated ketone 2 to the 4β-deuterio isomer 4 shows the reaction to proceed with retention at C-1 and inversion at C-10. The 4-substituted testosterone derivatives 33 – 36 (Chart 8) were found to be much less reactive in general than 1 . In particular, 4-methyl ketone 33 remains essentially unchanged on irradiation in t-butanol, benzene and toluene.     

Détermination par RMN 1H et 13C des Couplages J(CH) et J(CC) dans des Monomères Precurseurs de Lignine: Vanilline,Férulate d'Ethyle et Alcool Coniférylique Sélectivement Enrichis en 2H et 13C

Some monomer model compounds of lignin have been selectively ²H and ¹³C labelled: vanillin, ethyl ferulate, coniferyl alcohol and ethyl hydrogen malonate. Deuterium isotope effects on the ¹³C chemical shifts in [formyl-²H]vanillin, [5-²H]vanillin and [α,α,5-²H₃]coniferyl alcohol made the unambiguous assignment of the aromatic ¹³C signals possible. Absolute ^1,2,3J(CC) values have been determined on ¹³C spectra of [formyl-¹³C]vanillin, and of ethyl ferulate and coniferyl alcohol in which the vinylic C-γ and C-β carbons were ¹³C enriched. It has been possible to measure ⁴J(C?O, C-4) in vanillin and ⁴J(C-γ, C-4) in ethyl ferulate. The determination of ^1,2,3,4J (CH) absolute values was done by means of gated decoupled ¹³C spectra of the non-labelled compounds. When second order effects made the use of this technique impossible we determined certain J(CH) values and their signs either by analysing the ¹H NMR spectra of ¹³C labelled coniferyl alcohol [²J(C-β, H-γ), ²J(C-β, H-α), ²J(C-γ, H-β), ³J(C-γ, H-α)] or by a double irradiation experiment on the 250 MHz ¹H NMR spectrum of ethyl [β-¹³C] ferulate [for ²J(C-β, H-γ)].     

Hydrogen migrations in mass spectrometry. II—single and double hydrogen migrations in the electron impact fragmentation of n-propyl benzoate

The sources of the migrant hydrogen atom(s) in reactions (a) and (b) in the electron impact mass spectrum of n-propyl benzoate have been investigated: (a) [C₆H₅CO₂C₃H₇]⁺ →[C₆H₅CO₂H]⁺ + C₃H₆; (b) [C₆H₅CO₂C₃H₇]⁺ → [C₆H₅CO₂H₂]⁺ + C₃H₅^sdot;. Deuterium labelling of the propyl group showed that, for reaction (a) at 70 eV ionizing energy 3 ± 1% of the hydrogen originates from C-1 of the propyl group, 86 ± 4% from C-2 and 11 ± 3% from C-3. The specificity of the transfer from C-2 increases as the internal energy of the fragmenting ions decreases, indicating that the results cannot be rationalized in terms of H/D interchanges between positions in the propyl group, but rather that the reaction involves specific, competing, H transfer reactions from each propyl position, in contrast to the high site specificity characteristic of the McLafferty rearrangement. Reaction (b) involves, almost exclusively, transfer of one hydrogen from C-2 and one from C-3 with only very minor participation of C-1 hydrogens. The [C₆H₅COOH]⁺ ion produced in reaction (a) fragments further to [C₆H₅CO]⁺ + OH. and the labelling results indicate some interchange of the carboxylic hydrogen with (ortho) ring hydrogens for those ions fragmenting in the first drift region. The extent of interchange is less than that observed for fragmentation of the same ion produced by direct ionization of benzoic acid or by reaction (a) in ethyl benzoate.     

Substituierte 9-Oxabicyclo[4.2.1]- und 9-Oxabicyclo[3.3.1]nonane IV. endo,endo-2,5-Dihydroxy-9-oxabicyclo[4.2.1]nonan,endo, endo-, endo,exo- und exo,exo-2,6-Dihydroxy sowie endo,exo-2,7-Dihydroxy-9-oxabicyclo[3.3.1]nonan; Darstellung und Umwandlungsprodukte

The synthesis of the following compounds and reaction products thereof are described: endo, endo-2,5-dihydroxy-9-oxabicyclo[4.2.1]nonane ( 3–5 ), epimeric 2,6-dihydroxy-9-oxabicyclo[3.3.1]nonanes (endo, endo: 6–8 , exo, exo: 29–32 , and endo, exo: 43–45 ), and endo, exo 2,7-dihydroxy-9-oxabicyclo[3.3.1]nonane ( 46–50 ).     

A 13C- and 195Pt-NMR. Study of the Complexes trans-PtCl2 (amine) (CH2CH2)

¹³C- and ¹⁹⁵Pt-NMR. spectra for the complexes trans-PtCl₂(amine)(CH₂?CH₂) have been measured. For amine = (S)-N-methyl-α-methylbenzylamine the two diastereomers present may be distinguished from the values ³J(Pt,C). The ¹⁹⁵Pt-chemical shift is shown to be sensitive to subtle differences stemming from intramolecular non-bonded interactions.