Bestimmung des Chiralitätssinns der enantiomeren 2,6-Adamantandiole

Determination of the Chirality Sense of the Enantiomeric 2,6-Adamantanediols The enantiomers of 2,6-adamantanediol ( 1 ) are resolved via the diastereoisomeric camphanoates. The (2R,6R)-chirality sense for (?)- 1 and (2S,6S) for (+)- 1 was determined by chemical correlation with (?)-(1R,5R)-bicyclo[3.3.1]nonan-2,6-dion ((1R,5R)- 3 ) of known absolute configuration in the following way: alkylation of the bis(pyrrolidine enamine) of (?)-(1R,5R)- 3 with CD₂I₂ and hydrolysis of the product gives the enantiomer 4 of (4,4-D₂)-2,6-adamantanedione. Reduction of 4 with LiAlH₄ leads to one enantiomer (Scheme 2) of each of the three diols 5 – 7 of known absolute configuration. The three diols are themselves configurational isomers due to the presence of the CD₂ group, but correspond otherwise entirely to the enantiomeric diols 1 . Accordingly, they can also be separated by means of their diastereoisomeric camphanoates to give the diols 5 / 6 and 7 . These samples are easily distinguished and identified by their characteristic ¹H-NMR spectra (cf. Fig. 2). This allows to identify the (2R,6R)- and (2S,6S)-enantiomer of 1 on the basis of their behavior in the resolution experiment analogous to that of the diols 5 / 6 and 7 , respectively. The diol (?)- 1 must have the (2R,6R)-configuration because it forms, like the diols 5 / 6 , with (?)-camphanic acid the diastereoisomeric ester less soluble in benzene. The diol (+)- 1 has (2S,6S)-configuration, because it forms, like 7 , with (+)-camphanic acid the diastereoisomeric ester less soluble in benzene. The bis(4-methoxybenzoate) of (?)-(2R,6R)- 1 shows chiroptical properties which are in accordance with Nakanishi's rule for two chromophores having coupled electric dipol transition moments arranged with a left-handed torsion angle.     

Neue Synthese von (−)-(R)-Cembren A,Synthese von (+)-(R)-Cembrenen und (+)-(S)-Cembren

Novel Synthesis of (?)-(R)-Cembrene A, Synthesis of (+)-(R)-Cembrenene and (+)-(S)-Cembrene A novel synthesis of (?)-(R)-cembrene A ((?)- 3 ) was developed using the Sharpless epoxidation for the introduction of the chiral center. Furthermore, the synthesis of (+)-(R)-cembrenene ((+)- 4 ) showed that this cembranoid must have the (R)-configuration and not, as previously reported, the (S)-configuration. Selective hydrogenation of (+)- 4 afforded (+)-(S)-cenibrene ((+)- 5 ).     

Photochemische Reaktionen. 87. Mitteilung. Zur Photolyse von 9-Oxabicyclo[3.3.1]nonan-2-on

Photolysis of Bicyclo[3.3.1]nonan-2-one. Disproportionations, the secondary processes available to the acyl-alkyl biradical b (X(9) = 0) formed from 9-oxabicyclo[3.3.1]-nonan-2-ones a (X(9) = 0) in a primary photochemical process by α-cleavage (Norrish type I cleavage) were studied. Special attention was paid to the selectivity between the two possible H-abstractions: the one at C(3) (→ ketene c , X(9)= 0) and the other one at C(8) (→ alkenal d , X(9) = 0) and to the selectivity of the H-abstraction at a definite methylene group (C(3) or C(8)). In the case of ketene formation (→ c , X(9) = 0) the specificity of the insertion of the migrating H-atom at C(1) was studied. endo-6-Hydroxy-9-oxabicyclo[3.3.1]nonan-2-one ( 6 ) and derivatives of it ( 7, 8, 16, 17, 19, 21, 30 and 38 ) as well as exo-6-hydroxy-9-oxabicyclo[3.3.1]-nonan-2-one ( 41 ) and its derivative 42 were used as substrates. UV.-irradiation of 6 in benzene yielded 1,5-dioxa-2-cis-decalone ( 44 ) by way of a ketene g (R = H) as demonstrated by the photolysis of 7 (→ 45 ), 8 (→ 43 ), and 17 (→ 47 ). Specific labellings with deuterium proved that H-abstraction occurs intramolecularly at C(3) (e.g. 16 → 54 ; 6 + 16 → 44 + 54 ), that one of the H-atoms at C(3) migrates specifically to C(1) ( 21 → 55 ; 19 → 56 ), endo-H–C(3) being favored by a factor of 6. The abstraction showed an unexpected primary isotope effect of about 2. UV-irradiation of 41 in benzene yielded in addition to the expected 1,5-dioxa-2-trans-clecalone ( 63 ) about 3% of an isomeric compound 67 which probably results from H-abstraction at C(8) (→ alkenal 65) followed by cyclisation.     

Zur Photochemie von (Z,Z)-2,7-Cyclodecadien-1-on und 4,8-Cyclododecadien-1-on. Synthese und Eigenschaften von Tricyclo[5.3.0.02,8]decan-Systemen

On the Photochemistry of (Z,Z)-2,7-Cyclodecadien-1-one and 4,8-Cyclododecadien-1-one. Synthesis and Properties of Tricyclo[5.3.0.0^2,8]decane Systems Irradiation of (Z,Z)-2,7-cyclodecadien-1-one ( 3 ) yields (Z,Z)-3,7-cyclodecadien-1-one ( 12 ) or tricyclo-[5.3.0.0^2,8]decan-4-one ( 16 ), depending on the reaction conditions. Irradiation of 4,8-cyclododecadien-1-one ( 28 ) results also in a light-induced transannular [2 + 2] cycloaddition, yielding tetracyclo[7.3.0.0^2,100^3,6]dodecan-1-one ( 30 ). Starting from 16 , the preparation of tricyclo[5.3.0.0^2,8]dec-4-ene ( 19 ), tricyclo[5.3.0.0^2,8]dec-4-ene ( 21 ) and tricyclo[5.3.0.0^2,8]deca-3,5-diene ( 24 ) is described. The ¹H-NMR and ¹³C? NMR spectra of the newly prepared compounds are discussed. In the case of 19, 21 , and 24 , the electronic structure is discussed on hand of their PE spectra.     

Hydroxyalkylierungen von Cystein über das Enolat von (2R,5R)-2(tert-Butyl)-1-aza-3-oxa-7-thiabicyclo[3.3.0]octan-4-on und unter Selbstreproduktion des Ciralitätszentrums

Hydroxyalkylations of Cysteine through the Enolate of (2R,5R)-2(tert-Butyl)-1-aza-3-oxa-7-thiabicyclo[3.3.0]octan-4-one with Self-Reproduction of the Center of Chirality The heterobicyclic compound 1 specified in the title is readily prepared as a single stereoisomer from (R)-cysteine, formaldehyde, and pivalaldhyde. While it is not possible to generate the enolate 10 from 1 qunatitatively – due to β-elimination of thiolate (→6) – an in-situ addition to aromatic aldehydes such as benzaldehydes (→13–16) , pyrrol-, furan-, and thiophen-2-carbaldehydes (→17–19) , pyridine-3-carbaldehyde (→21) , as well as to other non-enolizable aldehydes like cinnamaldehyde (→22) , can be achieved in yields of ca. 50%. The adducts ( 8 and 9 ) of lithium diisopropylamide or t-butoxide to these aldehydes are acting, probably as bases for deprotonation and as in-situ sources of the electrophilic aldehyde species (cf. 11, 12 ). - Of the four possible diastereoisomeric products, one is usually formed with >90% selectivity (Table). It is assumed that the preferred stereochemical course of the reaction corresponds to that observed previously with the analogous proline-derived enolate (See 23,24 ). A chemical correlation with l-α-methyl-β-phenylserine (25) proves the relative configuration of the benzaldehyde adduct 13 . All hydroxyalkylated products (13–19, 21, 22) are obtained as crystalline, diastereoisomerically pure compounds and are fully characterized. – The benzaldehyde derivative 13 was used to exemplify the various possible transformations of these products to monocyclic or acyclic amino-acid derivatives such as the oxazolidionenes 26 and 29 (cleavage of the ring containing the S -atom), the thiazolidines 28 , 31 , and 32 (cleavage of the cyclic N,O-acetal) and the α-branched cysteine 27 and the phenylserines 25 and 30 (cleavage of both rings to give open-chain aminoacids).     

Über die Synthese von 4-Phenyl-[1,4]-diazepino[6,7,1-kl]phenthiazin-1(2H)-on

The preparation of 4-phenyl-[1.4]-diazepino[6.7.1-kl]phenothiazin-1(2H)-one (5) is described and some of its properties are compared with those of 1.4-benzodiazepines.     

Eine Synthese von Bicyclo[10.3.0]pentadec-1(12)-en-13-on und seinem 14-Methylderivat

A Synthesis of Bicyclo[10.3.0]pentadec-1(12)-en-13-one and its 14-Methyl Derivative. A new route to bicyclo[10.3.0]pentadec-1(12)-en-13-one ( 2 ) and its 14-methyl derivative 3 – useful intermediates in the synthesis of cyclopentadecanone ( 4 = exaltone®) and rac-muscone ( 5 ) – is described.     

Synthese und Kristallstruktur von (PPh4)2[Mo2Cl10]

Synthesis and Crystal Structure of (PPh₄)₂[Mo₂Cl₁₀] The title compound is obtained in the reaction of [MoCl₄(Ph? C?C? Ph)]₂ with tetraphenylphosphonium chloride in dichloro methane, forming brown crystals. It is characterized by the i.r. spectrum and a crystal structure analysis by the aid of X-ray diffraction data. The complex crystallizes triclinic in the space group P1 with one formula unit per unit cell. The cell dimensions are a = 1122 pm, b = 1137 pm, c = 1283 pm; α = 63.4°, β = 69.1°, γ = 86.5°. The crystal structure determination (2959 observed, independent reflexions, R = 4.5%) shows the constants of the unit cell to consist of on centrosymmetric anion, two cations and one disordered molecule of dichloro methane. The distance Mo? Mo in the anion is 380 pm, which excludes direct magnetic interaction between the molybdenum atoms.     

γ-anti-Effekt an 1-Phosphabicyclo[3.3.1]nonan-Derivaten mit Substituenten am Phosphor. Synthese und Struktur von Pentacarbonyl(1-phosphabicyclo[3.3.1]nonan)chrom

γ-Anti Effect in 1-Phosphabicyclo[3.3.1]nonane Derivatives with Substituents at Phosphorus. Synthesis and Structure of Pentacarbonyl(1-phosphabicyclo[3.3.1]nonane) Chromium In 1-phosphabicyclo[3.3.1]nonane derivatives of the composition C₈H₁₅P(X) the CC-conformation always dominates. Changes in the chemical shifts of the bridge-head carbon atom C(5) in the ¹³C-NMR spectrum are only originated by the electronic influence of the substituent X at the phosphorus centre. Based on a homogeneous interpretation of the electronic interactions and with regard to Pearsons's definition of electronegativity the electronegativities of substituents at the phosphorus atom X = Cr(CO)₅, Fe(CO)₄, and Ni(CO)₃ are estimated. These groups are placed in antiperiplanar orientation to the carbon atom C(5). The molecular structure of (1-phosphabicyclo[3.3.1]-nonane) Cr(CO)₅ 3 was elucidated by X-ray diffraction analysis. The molecule features the 1-phosphabicyclononane ligand in the CC-conformation, which has a nearly undistorted Cr(CO)₅ unit coordinated to the phosphorus atom (d Cr P = 2.368(1) Å).     

The conformation of (1R,2S,4R,5S)-2,4-dimethoxybicyclo[3.3.1]nonan-9-one and some related compounds

A mixture of stereoisomers of 2,4-dimethoxybicyclo[3.3.1]nonan-9-one was prepared, separated by column chromatography and characterized by 60 MHz ¹H NMR spectroscopy using Eu(fod)₃. A double chair conformation with axial methoxyl groups is established for (1R,2S,4R,5S)-2,4-dimethoxybicyclo[3.3.1]-nonan-9-one on the basis of the J(12), J(2,H-3 exo) and J(2,3 endo) values and the chemical shifts for H-2(4). The conformation of some related compounds is subsequently inferred.     

Synthese von Bicyclo[3.3.o]oct-1(5)en-2-on aus Cyclohexanon

Synthesis of Bicyclo[3.3.0]oct-1(5)en-2-one from Cyclohexanone Treatment of 2-nitrocyclohexanone ( 2 ) with acrylaldehyde yielded in the presence of tetrabutylammonium fluoride the bicyclic product 5 , which was oxidized to the nitro-diketone 3 . The conversion of 3 to the title compound 1 was achieved in the nearly quantitative yield under unusual conditions: K₂CO₃/H₂O and H₂SO₄. Compound 3 , was also converted to 1 (stepwise and one-pot reaction, respectively) by treatment with 1. NaOCH₃, 2. TiCl₃, and 3. H₂SO₄ (Scheme).     

Synthese und Kristallstruktur von [Na(12-Krone-4)2]2[Hg(Se4)2] · 1,5 DMF

Synthesis and Crystal Structure of [Na(12-Crown-4)₂]₂[Hg(Se₄)₂] · 1.5 DMF . The title compound has been prepared by the reaction of Na₂Se₄ with mercury acetate in DMF solution in the presence of 15-crown-5, forming dark red crystal needles. [Na(12-crown-4)₂]₂[Hg(Se₄)₂] · 1.5 DMF crystallizes in the space group C2/c with eight formula units per unit cell. The structure was determined with 3 824 observed unique reflections, R = 0.085. Lattice dimensions at - 70°C: a = 2 884(2), b = 1 407.7(7), c = 2 843(2) pm, β = 93.93(5)°. The structure consists of [Na(12-crown-4)₂]⁺ ions with a sandwichlike coordination of the crown ether molecules, and of [Hg(Se₄)₂]^2? ions, in which the mercury atom is coordinated by two tetraselenido ions in a chelating fashion. The [Hg(Se₄)₂]^2? ions are arranged to infinite chains via Se…?Se contacts.     

Synthese und Kristallstrukturen von [Ti(NPh2)4] und [Ti2(μ-O)(NPh2)6]

Crystal Structures of [Ti(NPh₂)₄] and [Ti₂(μ-O)(NPh₂)₆] [Ti(NPh₂)₄] has been prepared from TiCl₃(THF)₃ and LiNPh₂, the μ-oxo complex [Ti₂(μ-O)(NPh₂)₆] results from partial hydrolysis of [Ti(NPh₂)₄] in toluene solution. Both complexes are characterized by crystal structure determinations. In [Ti(NPh₂)₄] the titanium atom is coordinated by the four nitrogen atoms in a distorted tetrahedral fashion with Ti–N bond lengths of 193.8 pm in average. In [Ti₂(μ₂-O)(NPh₂)₆] the μ-oxo ligand forms a linear symmetric TiOTi bridge with rTiO = 181.2 pm and TiN = 193.4 pm in average.     

Zur Synthese von 9,9-Dimethyl-2-oxa-bicyclo[3.3.1]nonan

Summary The diketone1 undergoes base induced ring opening to the -ketoacid2 a. Subsequent stereoselective reduction of the carbonyl-group affords the corresponding hydroxyacid4 a and condensation leads to the bicyclic lactone5 which can be reduced to the title compound6. Similar O-cage-compounds are known for antiviral activity. The olfactory properties of the compounds5 and6 are described.