1,5-Aza-phosphabicyclo[3.2.1]octan - Bildung und Reaktionsverhalten

1,5-Aza-phosphabicyclo[3.2.1]octane. Synthesis and Reactivity The cyclization reaction of β-allylamino-ethyl-phosphin in presence of paraform-aldehyde and ethanol lead to 1,5-aza-phosphabicyclo[3.2.1]oetane 1 with N-alkyl-1, 3-azaphospholane as intermediate. On the other hand the components produce in benzene 1 and 5-methyl-1, 4-aza-phosphabicyclo[2.2.1]heptane. 1 shows the same reactivity as 6-methyl-1,5-aza-phosphabicyclo[3.2.1]-octane and also in the case towards alkyl halides the nitrogen is more nucleophilic than phosphorus. The n.m.r. data of the compounds described are discussed.     

Synthese von endo- und exo-1,3-Dimethyl-2,9-dioxa-bicyclo[3.3.1]nonan

Synthesis of endo- and exo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nonane The synthesis of a host-specific substance in norway spruce infested by Trypodendron lineatum OLIV . is described (cf. scheme 1 and 2). Alkylation of the acetyl-acetone di-anion (II) with 3-methyl-3-buten-1-yl-bromide (I) followed by sodium boro-hydride reduction yields erythro- and threo-8-methyl-8-nonen-2,4-diol (IV and V) which are separated by chromatography. Their configurations were established by converting them under equilibrium conditions into one (VI) or two (VII and VIII) benzal derivatives. Oxidative cleavage with ozone of the terminal double bond in the erythro diol IV produces a dihydroxy ketone IX which spontaneously cyclizes to endo-1,3-dimethyl-2,9-dioxa-bicyclo[3.3.1]nonane (X). The threo diol V is converted by the same reaction sequence exclusively into exo-1,3-dimethyl-2,9-dioxa-bicyclo-[3.3.1]nonane (XII). Comparison of the NMR. data of the two acetals X and XII with that of the natural product establishes the endo configuration of the latter. A second, more convenient, synthesis of a mixture of the acetals X and XII starting from the bromo-acetal XIII is also reported.     

Die Cyclopropylcarbinyl-Cyclobutyl-Homoallyl-Umlagerung. I. Teil. Synthese von Tricyclo[3.2.1.02,7]octan-3-ol,endo- und exo-Tricyclo[3.2.1.03,6]octan-4-ol und exo-Bicyclo[3.2.1]-oct-2-en-7-ol

Tricyclo[3.2.1.0^2,7]octan-3-ol ( 1 ) and its 4-isomer 7 were obtained by hydroboration of tricyclo[3.2.1.0^2,7]oct-3-ene ( 5 ). The former alcohol 1 is quantitatively converted to the isomeric alcohol exo-bicyclo[3.2.1]oct-2-en-7-ol ( 3 ) by treatment with aqueous acid. Photolysis of 1-diazo-3-(cyclopent-3-enyl)-propan-2-one ( 12c ) gave a high yield of tricyclo[3.2.1.0^3,6]octan-4-one ( 10a ). Reduction of the latter ketone produced a mixture of endo- and exo-tricyclo[3.2.1.0^3,6]octan-4-ol 2 and 9 , respectively. Oxidation of these secondary alcohols with silver carbonate in benzene furnished a mixture of the ketone 10a and the lactone 14 of 6-hydroxy-bicyclo[2.1.1]heptane-2-carboxylic acid. The latter is thought to be formed by oxydation of the hydrate of the strained ketone 10a .     

Enthalpie der Polymerisation von 7-Oxabicyclo[2.2.1]-heptan sowie exo- und endo-2-Methyl-7-oxabicyclo-[2.2.1]-heptan

Ohne Zusammenfassung     

Polymerisation von bicyclischen Acetalen. 3. Mitt. Kationische Copolymerisation von 6,8-Dioxabicyclo[3.2.1]octan mit Styrol

Ohne Zusammenfassung     

A mass-spectral study of exo- and endo-2-norbornyl bromide and exo and endo-8-bromobicyclo[3.2.1]octane by photoionization

The photoionization, as well as the electron-impact, mass spectra of exo-and endo-norbornyl bromide and of exo-and endo-8-bromobicyclo[3.2.1]octane show that exo-Br loss is more facile than endo-Br loss in formation of C₇H₁₁^⊕ and C₈H₁₃^⊕, respectively. The relative intensity values are compared with solvolysis data from the same systems.     

Die Cyclopropylcarbinyl-Cyclobutyl-Homoallyl-Umlagerung II. Teil. Produkte und Geschwindigkeit der Umlagerung von Tricyclo[3.2.1.02,7]octan-3-ol-, endo- und exo-Tricyclo-[3.2.1.03,6]octan-4-ol und exo-Bicyclo[3.2.1.]oct-2-en-7-ol-Derivaten

Solvolyses of the 2,4-dinitrobenzoates of the cyclopropylcarbinol 1a , the cyclo-butanol 2a and the homoallylic alcohol 3a in buffered 70% aqueous dioxane lead to the same product mixture consisting of 78% cyclopropylcarbinol 1a and 22% homoallylic alcohol 3a . Approximately the same product mixture is optained when the homoallylic chloride 3b and the cyclopropylcarbinyl p-nitrobenzoate 1c are solvolyzed. A common cationic intermediate is indicated in these kinetically controlled rearrangement reactions. Under conditions of thermodynamic control only homoallylic products are formed. The 2,4-dinitrobenzoates 1d and 2d react 7.2 × 10³ and 7.7 times, respectively, as fast as the homoallylic isomer 3d . Since the homoallylic chloride 3b reacts ca. 10⁵ times as fast as its saturated analogue, 7-exo-bicyclo[3.2.1]octyl chloride 4 , all three esters react with the enhanced rates which are characteristic of these structural types. The endo-cyclobutyl dinitrobenzoate 2d reacts more than 60 times as fast as its exo-isomer 6d . The rate difference is ascribed to a stereoelectronically more favorable orientation of the participating σ bonds in the puckered cyclobutane ring in the endo isomer 2d .     

Synthesis und thermisches Verhalten von exo-3-Methylidentricyclo[3.2.1.02,4]oct-6-en

Synthesis and Thermal Behaviour of exo-3-Methylidenetricyclo[3.2.1.0^2,4]oct-6-ene The title compound 3 has been prepared in 16% yield starting from 8,9,10-trinorborna-2,5-diene. Heating 3 at 140° for 4 h does not give triafulvene and cyclopentadiene by Diels-Alder cycloreversion, instead the tetracyclic compound 10 has been isolated (81%), which is presumably formed via the diradical 11.     

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 ).     

Die C8H12-Energiehyperfläche Thermolyse von syn- und anti-Tricyclo[4.2.0.02,5]octan. Experimentelle und theoretische Untersuchungen

The C₈H₁₂-Energy Hypersurface Thermolysis of syn- and anti-Tricyclo[4.2.0.0^2,5]octane. Experimental and Theoretical Studies The thermal behaviour of syn- and anti-tricyclo[4.2.0.0^2,5]octanes 9 and 10 in the gas phase as well as in solution is investigated. Two Mayn products are formed in parallel reactions: cis, cis-1,5-cyclooctadiene ( 11 ) and cis, trans-1,5-cyclooctadiene ( 15 ), the latter being partly isomerized to 11 under the reaction conditions. Minor products are cis-1,2-divinylcyclobutane ( 6 ), trans-1,2-divinylcyclobutane ( 16 ) and 4-vinyl-1-cyclohexene ( 17 ). Thermolysis of cis-1,2-divinylcyclobutane leads to small amounts of cis, trans-cyclooctadiene, presumably via a four-centre transition state. The tricyclics most likely prefer a stepwise isomerization. The decisive product-controlling factor seems to be the conformational mobility of intermediate diradicals. By comparison with the boat-Cope reaction of divinylcyclobutane the pericyclic six-centre transition state of this rearrangements is shown to lie energetically about 19 kcal/mol below the transition states in the thermolysis of 9 and 10 . The azo compound 12 on heating fragments predominantly in a concerted manner in contrast to the photolysis. Theoretical methods are applied to unveil structure and bonding in the supposed intermediate diradicals.     

Polymerisation von bicyclischen Acetalen. 2. Mitt. Sterischer Verlauf der kationischen Polymerisation von 6,8-Dioxabicyclo [3.2.1]octan

Ohne Zusammenfassung     

Mesityltrifluorogallate. Die Kristallstrukturen von Cs[MesGaF3] und K[MesInBr3]

Mesityltrifluoro Gallates. The Crystal Structures of Cs[MesGaF₃] and K[MesInBr₃] Mes₃Ga reacts with GaBr₃ in the ratio 1:2 in a commutation reaction to MesGaBr₂ ( 1 ). 1 can be reacted with KF and CsF in MeCN to K[MesGaF₃] ( 2 ) and Cs[MesGaF₃] ( 3 ), respectively. K[MesInBr₃] ( 4 ) was isolated when MesInBr₂ was treated with KF in MeCN. The use of 15-crown-5 was leading to [K(15-crown-5)₂][Mes₂InBr₂] ( 5 ) in a substituent exchange reaction. 1-5 were characterized by NMR-, IR- and MS-techniques. The solid state structures of 3 and 4 could be established by X-ray structure determinations. According to these determinations, a layer-type arrangement of the molecules is both structures in common. In the center of the layers, ionic interactions were formed, while the separation of the layers is caused by the bulky mesityl substituents.     

Die Solvolyse von Trialkoxy-acetoxy-silanen in i-Propanol

Solvolysis of Trialkoxy-acetoxy- Silanes in i-Propanol Trialkoxy-acetoxy-silanes (RO)₃Si? O? CO? CH₃ [R = i-C₃H₇? , s-C₄H₉? ] are solvolysed in benzene/i-propanol-mixtures. Rates of CH₃COOH formation are investigated in order to compare them with results of R₃Si? O? CO? CH₃ i-propanolysis.     

Darstellung und Schwingungsspektren von Dichloro- und Dibromodithiophosphat Die Kristallstrukturen von [PPh3Me] [PS2Cl2] und [PPh4] [PS2Br2]

Preparation and Vibrational Spectra of Dichloro and Dibromodithiophosphate. Crystal Structures of [PPh₃Me][PS₂Cl₂] and [PPh₄][PS₂Br₂] Dichloro and dibromodithiophosphates [Cat⁺][PS₂X₂^?] with a large organic cation can be obtained from P₄S₁₀, CatX and HX in CH₂Cl₂ (Cat⁺ = PPh₄⁺, PPh₃Me⁺; X = Cl, Br). The vibrational spectra (i.r. and Raman) of the [PS₂X₂]^? ions are reported and discussed; force constants were calculated. The crystal structures of [PPh₃Me][PS₂Cl₂] and [PPh₄][PS₂Br₂] were determined and refined with X-ray diffraction data. In both cases, simple anions [PS₂X₂]^? are present. [PPh₃Me][PS₂Cl₂]: orthorhombic, space group P2₁2₁2₁, a = 1089, b = 1334, c = 1476 pm, Z = 4, refinement to a residual index R = 0.046 for 1116 reflexions; the structure is isotopic with [PPh₃Me][VO₂Cl₂]. [PPh₄][PS₂Br₂]: tetragonal space group I4 , a = 1301, c = 721 pm, Z = 2, refinement to R = 0.065 for 357 reflexions; the structure is isotypic with [AsPh₄][FeCl₄] with [PS₂Br₂]^? ions occupying positions of 4 -symmetry with statistical orientation (statistical superposition of Br and S positions).     

Die Solvolyse von Tetranitromethan in verschiedenen polaren und unpolaren Lösungsmitteln

Ohne Zusammenfassung     

Low-Temperature Polymerization of endo- and exo-2-Methyl-7-oxabicyclo-[2.2.1]-heptane

Abstract

Polymerization of the title compounds in methylene di-chloride with PF, catalyst have shown that the rate of polymer formation drops sharply with temperature and the polymerization ceases entirely around -60 to -70°C. Ex-periments carried out with the exo-2-Me isomer have shown that at -30°C a limiting conversion of approx 40% is attained and simultaneously the molecular weight and the molecular weight distribution level off. At -50°C the same limiting conversion level is reached; however, the molecular weight level is higher and a study of changes in molecular weight distribution with time indicates that at this tempera-ture a greater proportion of chains remain active throughout the polymerization. Even at -30°C, however, experiments with changing conditions, especially the temperature, during the runs have demonstrated that the systems are not “dead” after the limiting conversion has been reached. Polymeriza-tion of the endo-2-Me isomer at -50°C has shown that in the time interval studied the limiting viscosity number increases essentially linearly with time.     

Stereospecific synthesis of exo- and endo-1,3-dimethyl-2,9-dioxabicyclo-[3.3.1]-nonane

The title compounds may be synthesised in an enantioselective and diastereospecific manner from (±)-4-hydroxynona-2,8-diene using the Sharpless asymmetric epoxidation as the key step in the reaction sequence.