Octane System Research Articles

Stereoselective synthesis of cyclic ether compounds via reductive cleavage of bicyclic ketals

AbstractBicyclic ketals in the 6,8‐dioxabicyclo[3.2.1]octane system readily reacted with triethylsilane‐boron tri‐fluoride etherate at room temperature to give only the cis‐tetrahydropyranol derivatives via C5‐O6 bond cleavage. Three‐ and erythro‐alcohols were prepared selectively from the endo‐ and exo‐ketal, respectively. Dehydrated products also formed when the tertiary alcohol was involved under these reaction conditions. However, the cleavage reaction with aluminum hydride gave the trans‐tetrahydropyranol as the major product without dehydration.

Utilization of Industrial Waste Materials, 10. – Synthesis of New Chiral Bicyclic 3‐hydroxypiperidines – Highly Diastereoselective Ring Expansion of the Azabicyclo[3.3.0]octane System to Chiral Piperidine Derivatives

AbstractNew, chiral bicyclic 3‐hydroxypiperidines (4S)‐2a–e are synthesized from the β‐amino alcohols (3R)‐1a–e. In an one‐step reaction (4S)‐2a–e are obtained by a high diastereoselective ring expansion (dr ⩾ 95:5). As well, the amino alcohol (3S)‐1a leads to the corresponding rearranged epimer bicyclic piperidine derivative (4R)‐2a (dr ⩾ 95:5). Thus, it is possible to clarify the influence of the three stereogenic centers of the parent compound regarding the diastereoselectivity of the ring expansion. After oxidation of the tert‐amino sec‐alcohol (4S)‐2a to the corresponding α‐amino ketone 4, new 3‐hydroxypiperidines (4Ξ)‐5a, b12 and (4RS)‐6 are obtained by a diastereoselective Grignard addition. Furthermore, the achiral and the chiral reduction of 4 to the β‐amino alcohols (4S)‐2a and (4R)‐2a is described. These are further examples of the utilization of industrial waste material (all‐R)‐2‐azabicyclo[3.3.0]octane‐3‐carboxylic acid (all‐R)‐3.

The Synthesis of Novel Trans-Oxabicyclo[3,3,0]octane Systems as Potential Inhibitors of HIV Protease

The novel trans-3-oxabicyclo[3,3,0]octan-7-one system has been prepared by intramolecular ring closure of the corresponding cyclopentane diol. Peralkylation and benzylidene substitution of the octanone has allowed the preparation of tetra-alkylated potential inhibitors of HIV protease. Weak activity against HIV protease (IC50's 70-100μM) was observed.

Structural elucidation of trichotetronines: polyketides possessing a bicyclo[2.2.2]octane skeleton with a tetronic acid moiety isolated from Trichoderma sp.

The isolation and structural elucidation of two novel fungal metabolites, trichotetronine and its dihydro congener, from Trichoderma sp. are described. The structures, including the relative and absolute stereochemistry, have been established using a variety of data including extensive NMR analyses and CD spectral studies. The compounds possess a bicyclo[2.2.2]octene system in conjunction with a tetronic acid moiety and two conjugated ketonic side chains. Along with them, trichodimerol, a known compound possessing an axis of symmetry, has been isolated. Both trichodimerol and the newly isolated trichotetronines appear to be derived from the condensation of two hexaketides having two extra methyl groups.

ChemInform Abstract: Bifunctional Reagents in Organic Synthesis: Stereocontrolled Methods for the Syntheses of Functionalized trans‐Fused Bicyclo(3.3.0)octane and Bicyclo(4.3.0)nonane Systems.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: A Facile, Expeditious Route to the Benzooxabicyclo(3.2.1)octane System. Application to a Short, High‐Yield Synthesis of Filiformin (VII).

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: A Novel Entry into the 6‐Azabicyclo(3.2.1)octane System via Radical Rearrangement of a Tropane Derivative.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Transannular Cyclizations in Caged Bislactones: Synthesis of Polyfunctional Cyclopentanes and Oxa-Cage Compounds

Abstract The reactions of dilactones based on bicycl[2.2.1] heptane and [2.2.2]octane systems with Grignard reagents and LiA1H4 furnished polyfunctional cyclopentanes and oxa-cage compounds resulting from extensive transannular interactions.

A novel entry into the 6-azabicyclo[3.2.1]octane system via radical rearrangement of a tropane derivative

The conversion of an enantiomerically pure tropane derivative, obtained from chromium(0)-promoted [6 π + 2 π] cycloaddition, into a functionalized 6-azabicyclo[3.2.1]octane has been achieved via a novel radical rearrangement process.

A Facile, Expeditious Route to the Benzooxabicyclo[3.2.1]octane System. Application to a Short, High-Yield Synthesis of Filiformin.

A facile and efficacious route to the benzooxabicyclo[3.2.1]octane system has been developed and applied to a synthesis of filiformin (1). The cycloaddition of ethylene to the methoxychromone 13 furnished the oxetanol 14 through a tandem cycloaddition and gamma-hydrogen abstraction sequence. Lithium aluminum hydride reduction to the diol 15 followed by acid-catalyzed rearrangement produced benzooxabicyclooctanone (16), arising from exclusive external bond migration. Similarly, ethoxychromone (17) under the same sequence of reactions afforded the homologous bridged ketone 20. For the synthesis of filiformin (1), methoxychromone 24 on ethylene cycloaddition followed by reduction of resultant oxetanol 25 with lithium aluminum hydride furnished diol 10. Acid-catalyzed rearrangement of 10 provided the bridged ketone 11 which was brominated to give 26. This bromo ketone had previously been converted to filiformin (1), and also aplysin 9, and hence, the present work represents a short, high-yield formal synthesis of these sequiterpenes from a single starting material.

Monophosphorylation of ethylenediamine with systems generating low-coordination phosphoryl species

Phenyldioxophosphorane was generated by thermal fragmentation of N-(1-adamantyl)phenylphosphonamidic acid in ethylenediamine to give a 61% yield of N-(2-aminoethyl)phenylphosphonamidic acid. The zwitterionic structure repressed reaction of the other amino group. Neopentyl metaphosphate and ethyl metaphosphate were generated in the presence of ethylenediamine by heating appropriate derivatives of the 2,3-oxaphosphabicyclo[2.2.2]octene system in toluene. Again, the metaphosphate phosphorylated only one amino group to give O-alkyl N-(2-amino-ethyl)phosphoramidic acids, in zwitterionic form. © 1996 John Wiley & Sons, Inc.

A facile and efficient route to the bicyclo[3.2.1]octane system. Application to the enantioselective approach to cyclopentanoids

The reaction of (4R,5R)-1-acetoxy-4-(1,2-epoxy-1-methyl-ethyl)-5-methylcyclohex-1-ene 8 with BF3·Et2O provides, in one chemical operation, (1R,4R,5R,7S)-7-acetoxy-4,6-dimethylbicyclo[3.2.1]octan-2-ones 9a,b which are then transformed to (2R,3R)-2-methyl-3-[(R)-1-methyl-3-oxobutyl]-cyclopentanone 16 with the same absolute configuration as that of the steroid D ring.

Concise Synthesis of 3-Hydroxy-Δ1.10−12,16-cyclogibberellin 12 Dimethyl Ester—A Trachylobagibberellin Analogue

Abstract Chemical synthesis of a trachylobagibberellin analogue - 3-hydroxy- δ1.10−12, 16-cyclogibberellin dimethyl ester 4 from gibberellin acid GA3 3 was described herein. The key step is the decomposition of the tosylhydrazone 11 to construct the novel [3.2.1.0.2.7] octane system.

Synthetic Studies on (±)-Antheridic Acid; Construction of the Antheridic Acid Skeleton

The establishment of a new synthetic method for exomethylenebicyclo[2.2.2]octene system and application for the framework construction of antheridic acid is presented.

Synthetic studies on (±)-antheridic acid; construction of the antheridic acid skeleton

The establishment of a new synthetic method for exomethylenebicyclo[2.2.2]octene system and application for the framework construction of antheridic acid is presented.

Synthesis of conformationally restricted analogs of kainic acid. Is the conformation of the C4-substituent of kainoid important to its neuroexcitatory activity?

Conformationally restricted analogs of kainic acid, which have an azabicyclo[3.3.0]octane system, were synthesized through the intramolecular addition reaction of trimethylenemethane to the α,β-unsaturated ester. Every synthesized isomer showed very weak depolarizing activity. These results indicate that the plane of the isopropenyl group of kainic acid should be diagonal to the pyrrolidine ring to show potent activity.

Radical reactions on furanoside acetals: First synthesis of sporothriolide and 4- [formula omitted]- ethisolide from ‘diacetone glucose’

First synthesis of sporothriolide ( 1) and 4- epi -ethisolide ( 2) is described, where the crucial bicyclo[3.3.0]octane systems 3 and 4 have been made by the adoption of regio- and stereoselective intramolecular radical cyclisation reaction onto the ‘chirons’ derived from ‘diacetone glucose’.

An improved preparation of diphenylmethylenecyclopropanes and their use in intramolecular palladium catalysed [3+2] cycloadditions

The synthesis and intramolecular palladium catalysed cycloaddition reactions of diphenylmethylenecyclopropanes 1 and 2 containing olefinic and acetylenic acceptors are described. This strategy provides a useful entry into some highly functionalised bicyclo[3.3.0]octane systems.

Radical reactions on furanoside acetals: A formal synthesis of (−)-canadensolide from D-mannose

By adaption of an intramolecular radical cyclisation protocol to the furanoid glycal derivative 3 derived from D-mannose, synthesis of the crucial bicyclo[3.3.0]octane system 6 is reported. A sequence of reactions on this key synthon 6, leading to the formal synthesis of (−)-canadensolide ( 1) is described.

Synthesis of conformationally restricted substance P antagonists

Reaction of CP-99,994 ( 1) with benzyl chloromethyl ether under basic conditions produced the novel 1,6-diazabicyclo[3.2.1]octane system in good yield; analogs containing this nucleus display high binding affinity for substance P receptors. The ethylene homologue of 1a, diamine 7, shows enhanced inhibitory activity and may more closely approximate the binding conformation of 1a at the NK 1 receptor.