Nonane Ring Research Articles

An N-Acyliminium Route to the 8-Azabicyclo[3.2.1]octane (Tropane) and the 9-Azabicyclo[4.2.1]nonane Ring System Synthesis of (±)-Anatoxin-A

An N-Acyliminium Route to the 8-Azabicyclo[3.2.1]octane (Tropane) and the 9-Azabicyclo[4.2.1]nonane Ring System Synthesis of (±)-Anatoxin-A

Thromboxane A2 analogues from 8-oxabicyclo[3.2.1]oct-6-en-3-ones

We describe approaches to thromboxane A2 analogues (3), (4), and (32) which contain 2,6-dioxabicyclo[3.2.1]octane and 2,6-dioxatricyclo[3.3.1.03,7]nonane ring systems. Both were derived from 2-substituted 8-oxabicyclo[3.2.1]oct-6-en-3-ones, which were in turn prepared by cycloadditions of suitable oxyallyls and furans.

Bridgehead reactivity, nucleophilic and radical additions, and lithium aluminum hydride reduction of 1-(arylsulfonyl)bicyclobutanes: general access to substituted, functionalized cyclobutanes. Syntheses of (.+-.)-citrilol acetate, (.+-.)-junionone, and the tricyclo[3.3.0.01,4]octane and tricyclo[4.3.0.01,7]nonane ring systems

Bridgehead reactivity, nucleophilic and radical additions, and lithium aluminum hydride reduction of 1-(arylsulfonyl)bicyclobutanes: general access to substituted, functionalized cyclobutanes. Syntheses of (.+-.)-citrilol acetate, (.+-.)-junionone, and the tricyclo[3.3.0.01,4]octane and tricyclo[4.3.0.01,7]nonane ring systems

Intramolecular alkylation route to the bicyclo[3.3.1]nonane ring system. A total synthesis of dl-clovene

Intramolecular alkylation route to the bicyclo[3.3.1]nonane ring system. A total synthesis of dl-clovene

Synthesis of sulfur‐bridged piperazinediones by reaction of 3,6‐dibromo‐1,4‐dimethyl‐2,5‐piperazinedione with geminal dithiols

AbstractThe reaction of several geminal dithiols with 3,6‐dibromo‐1,4‐dimethyl‐2,5‐piperazinedione gave in good yields piperazinedione derivatives substituted at the 3,6‐position with a geminal dithiol‐bridging group. These sulfur‐bridged piperazinediones formally represent derivatives of the 2,4‐dithia‐6,8‐diaza‐7,9‐dioxobicyclo[3.2.2]nonane ring system. Attempts to transform these sulfur‐bridged piperazinediones to 3,6‐epidithiopiperazinediones by removal of the bridging group common to the sulfur functionality were unsuccessful. Studies also are reported of addition of thioacetic acid to 3,6‐dimethylene‐2,5‐piperazinedione to give 3,6‐diacetylthio‐3,6‐dimethyl‐2,5‐piperazinedione. Conversion of the 3,6‐diacetylthio derivative to the epithiopiperazinedione ring system yielded a mixture of epimono‐ and epidithiopiperazinediones.

Intramolecular reactions involving positions C(2), C(6) and (C2), C(7) in the bicyclo[3.3.1]nonane ring system

Reactions likely to involve C(2)–C(6) and C(2)–C(7) intramolecular reactions in bicyclo[3.3.1]nonane derivatives are discussed in terms of the conformations available to the ring system. While endo-6-hydroxybicyclo[3.3.1]-nonan-2-one (11) incorporated three deuterium atoms (excluding the hydroxy-group) on heating with NaOD, the exo-isomer (17) exchanged the six hydrogens adjacent to the oxygenation functions but not the carbinyl proton. Evidence is presented favouring a stereospecific base-induced 2,6-hydride migration, most probably proceeding via a twin-twist boat transition state. Treatment of 6,6-ethylenedioxy-2-methoxymethylenebicyclo-[3.3.1]nonane (36) with aqueous HCl in acetone produced 2-hydroxyprotoadamantan-10-one (38) in high yield. This process resulted from hydrolysis of the oxygenated groups thereby liberating the endo-keto-aldehyde intermediate (37) which underwent subsequent intramolecular aldol condensation between the C(2) aldehyde and C(7).

Direct observation of boat–chair ⇌ chair–boat equilibrium in the 3,7-diazabicyclo[3.3.1]nonane ring

Variable-temperature 13C n.m.r. spectra of 3,7-dialkyl-1,5-diazabicyclo[3.3.1]nonan-9-ones unambiguously establish a boat–chair ⇌ chair–boat equilibrium rather than the fixed double-chair conformation which had previously been proposed.

A new route to the rare tricyclo[3.3.1.02,7]nonane skeleton. Synthesis of 1,2,3,4,7-pentafluorotricyclo[3.3.1.02,7]non-3-ene-8,8-diol hemihydrate via thermolysis of pentafluorophenyl prop-2-enyl ether, and related studies

Prolonged heating of pentafluorophenyl prop-2-enyl ether (1) in the vapour phase at 137–141 °C and hydration of the product gives a compound (10) incorporating the rare [3.3.1.02,7]nonane ring skeleton and containing a plane of symmetry. An analogous reaction occurs with pentafluorophenyl 2-methylprop-2-enyl ether. Some reactions of (10) are described.

Sesterterpenes. 1. Stereospecific construction of the ceroplastol and ophiobolin ring systems via a common bicyclic intermediate

The ring systems present in the two major classes of ophiobolane sesterterpenes have been obtained via a common bicyclic intermediate. In each case, the eight-membered ring was constructed by fragmentation of an appropriately functionalized bicyclo(3.3.1)nonane ring system.

An N.M.R. study of some esters and lactones derived from cineolic anhydride

Cineolic anhydride is attacked by nucleophiles exclusively at its more exposed carbonyl group. The dimethyl ester of cineolic acid has been studied by proton N.M.R. spectroscopy and its conformation assigned. Similar assignments have been made for cineolic anhydride and two lactones derived from it, examples of the 3,6-dioxabicyclo[3,2,2]nonane ring system. In each case the N.M.R. signal of the methine proton is simplified by the use of a lanthanide shift reagent so that the conformation can be deduced. The shift reagent removes the effect of virtual coupling to the methine proton.

X-Ray crystal structure determination of a new alkaloid, daphnilactone A, C23H35O2N

The structure of the title compound (I) has been determined from three-dimensional diffractometer data. The structure was determined directly by the symbolic addition procedure, and refined by least-squares methods to R 5·8% for 2014 observed non-zero reflections. The crystals are orthorhombic, space group P212121 with Z= 4 in a unit cell of dimensions: a= 14·258, b= 13·481, c= 10·090 A. The ring system of this alkaloid is novel but it has a 2-azabicyclo[3,3,1]nonane ring, a common moiety in daphniphyllum alkaloids.

Polyesters containing bicyclo[2.2.2]octane and bicyclo[3.2.2]nonane rings

AbstractPolyesters containing bicyclo[2.2.2]octane and bicyclo[3.2.2]nonane rings are prepared from 1,4‐bis(carboethoxy)bicyclo[2.2.2]octane, 1,4‐bis(hydroxymethyl)bicyclo[2.2.2]‐octane and the 1,5‐disubstituted bicyclo[3.2.2]nonane analogs. These polyesters are compared to the related polymers containing 1,4‐phenylene and trans‐1,4‐cyclohexylene rings in terms of their melting point, thermal stabilities and oxidative stabilities. The lower symmetry of the bicyclo[3.2.2]nonane ring produces lower‐melting polymers than the other ring systems. The remaining three rings are approximately equivalent in their effect on the melting point of a polymer provided that no more than one bicyclo[2.2.2]octane ring is present per polymer repeat unit. Two such rings produce a highermelting polymer than any other combination. Both the thermal and oxidative stabilities of the polyesters is improved by the presence of the bicyclo rings. This is attributed to the rings providing an approximation of a ladder polymer.

Study of furan compounds

By means of dioxane dibromide the bromination of number of homologs of 1,6-dioxaspiro[4.4]nonane was achieved, as a result of which nine mono and dibromo-derivatives of spiranes were obtained which have not been described in the literature. It was established that bromine enters into position 4 and 9 of the 1,6-dioxaspiro[4.4]nonane ring.

Synthesis of polymer intermediates containing the bicyclo[3.2.2]nonane ring

The preparation of 1,5-biscarbethoxybicyclo[3.2.2]nonane and 1,5-bis(hydroxymethyl)bicyclo[3.2.2]nonane is described. The procedure generally followed that reported for the analogous bicyclo[2.2.2]octanes. However, certain differences in chemical behavior were observed and are reported.The alkylation of the sodium salt of diethyl succinylsuccinate produced the expected 1,5-biscarbethoxybicyclo[3.2.2]nonane-6,8-dione along with a by-product which was shown to be 1,5-biscarbethoxybicyclo[4.2.1]nonane-7,9-dione. It was also shown that this compound arose by isomerization of the bicyclo[3.2.2]nonane analogue after the alkylation occurred.Conversion of these compounds to thioketals with 1,3-propanedithiol was also examined in detail. The reaction between 1,3-propanedithiol and 1,5-biscarbethoxybicyclo[3.2.2]nonane-6,8-dione generated an equilibrating system of 4 compounds. Three of these are shown to be the monothioketal, the bisthioketal, and a mixed thioketal–vinylthioether.

Spirocyclic tetrahydropyrimidines derived from pentaerythritol

A series of seven spirocyclic compounds bearing the newly synthesized 6,8-diaza-2-oxaspiro[3•5]nonane ring system are reported. Their preparation consists in the condensation of 3,3-bis(aminomethyl)oxetane monohydrate, obtained via pentaerythritol tribromide and, 3,3-bis(bromomethyl)oxetane, with certain amidines and guanidines.

Synthesis of bridged steroids. V. Cholestane derivatives having a bridged 3-azabicyclo[3.3.1]nonane ring system.

Cholestane derivative (IIb) having a bridged 3-azabicyclo [3. 3. 1] nonane ring system was synthesized from 3-oxo-5α-cholestane-5-carbonitrile (III) by a six-step reaction sequence. The over-all yield was very high indicating high stereospecificity or uniformity of the reaction used. Reduction of 3α-formyl-3β-methyl-5α-cholestane-5-carbonitrile (VIII) to the amino alcohol (Xa) was effected by means of lithium aluminum hydride reduction in the presence of aluminum chloride.

Synthetic Studies on the Lycopodium Alkaloids. II. A Synthesis of a Key Intermediate, 2, 3, 5, 6, 7, 8-Hexahydro-7β-methyl-3-oxo-1H-5, 8a-propenoquinoline, for the Lycopodium Alkaloids

The introduction of an amino function on the bridgehead position of the bicyclo (3, 3, 1) nonane ring system has been smoothly achieved by the modified Curtius reaction on some bridgehead carboxylic acids. This method has been applied on 3β-methyl-9-ox-obicyclo (3, 3, 1) non-6-ene-1-carboxylic acid (XIV) to afford the unsaturated aminoketone (XVI) as its hydrobromide via the carbamate. XVI was transformed into the tricyclic lactam (XVIII), via the pyruvamide (XVII) followed by cyclization. XVIII was then reduced via its lactim-ether followed by oxidation to afford 2, 3, 5, 6, 7, 8-hexahydro-7β-methyl-3-oxo-1H-5, 8α-propenoquinoline (XXI) in good yield, which would provide useful intermediate for syntheses of the lycopodium alkaloids.