Tricyclic Framework Research Articles

Formal Total Synthesis of Haouamine A

A synthesis of the indenotetrahydropyridine unit of haouamine A is described. The construction of a diaryl quaternary center and tricyclic framework of this compound was achieved by an intramolecular cascade Mizoroki-Heck reaction.

Skeletal and Stereochemical Diversification of Tricyclic Frameworks Inspired by Ca2+-ATPase Inhibitors, Artemisinin and Transtaganolide D

Inspired by the common skeletal motifs of Ca(2+)-ATPases inhibitors involving artemisinin and transtaganolide D, small molecule collections with the three-dimensional structural diversity of tricyclic systems were designed and expeditiously synthesized (4-5 steps). A synthetic strategy featuring stereochemical diversification of ring-junctions and control of cyclization modes was devised to access varied molecular architectures in a systematic fashion.

Formal Asymmetric Synthesis of (-)-Aphanorphine via Ring-Closing Metathesis Reaction

We have developed an asymmetric route to (-)-aphanorphine from O-Me-D-tyrosine methyl ester hydrochloride salt, available from D-tyrosine in four steps. The tricyclic framework of (-)-aphanorphine was assembled stereoselectively by intramolecular Friedel-Crafts reaction of the corresponding bicyclic precursor, which was in turn generated via ring-closing metathesis reaction.

8-Chloro-5-(4-phenethylpiperazin-1--yl)pyrido[2,3-b][1,5]benzoxazepine.

As part of an anti­psychotic drug discovery program, we report the crystal structure of the title compound, C24H23ClN4O. The mol­ecule has a tricyclic framework with a characteristic buckled V-shaped pyridobenzoxazepine unit, with the central seven-membered heterocycle in a boat configuration. The piperazine ring displays a chair conformation with the 2-phenyl-ethyl substituent assuming an equatorial orientation. There are two crystallographically independent, but virtually identical, mol­ecules in the asymmetric unit.

Facile synthesis of 6‐aryl‐5H‐8‐oxa‐4b, 7‐diaza‐benzo[a]azulen‐9‐one derivatives, new tricyclic heterocycles

Abstractmagnified image8‐Oxa‐4b,7‐diaza‐benzo[a]azulene‐9‐one system, a new tricyclic heterocyclic framework is designed through a simple and convenient synthetic sequence. Its 6‐aryl derivatives are synthesized starting from ethyl indole‐2‐carboxylate. Reaction of differently substituted phenacyl bromides with ethyl indole‐2‐carboxylate, treatment of the resultant N‐substituted indole‐2‐carboxylates with hydroxylamine hydrochloride to provide corresponding oximes, subsequent ester hydrolysis followed by dehydrative cyclisation furnished the desired compounds 5 a‐g.

Enantiocontrolled Synthesis of (−)-9-epi-Pentazocine and (−)-Aphanorphine

We have developed novel asymmetric routes to (-)-9- epi-pentazocine and (-)-aphanorphine from a d-tyrosine derivative. The tricyclic frameworks of (-)-9- epi-pentazocine and (-)-aphanorphine were assembled stereoselectively via intramolecular Friedel-Crafts reaction of the corresponding bicyclic precursors, generated with titanium-promoted enyne cyclization and indium-initiated atom-transfer radical cyclization, respectively.

ChemInform Abstract: Highly Regio‐ and Stereoselective Synthesis of Tricyclic Frameworks Using Baylis—Hillman Derivatives.

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A Synthesis of the Tricyclic Core Structure of FR901483 Featuring an Ugi Four-Component Coupling and a Remarkably Selective Elimination Reaction

Three key reactions, an efficient Ugi four-component coupling, a regiospecific, base-mediated elimination reaction, and an intramolecular nitrone/alkene [3+2] cycloaddition, were used to achieve an effective synthesis of the tricyclic molecular framework of the immunosuppressant FR901483. The outcome of a control experiment supports the idea that an internal deprotonation by an alkoxide ion is the origin of the site selectivity observed in the base-induced elimination of hydroxy mesylate 17.

Highly regio- and stereoselective synthesis of tricyclic frameworks using Baylis–Hillman derivatives

A simple and convenient synthetic route for the synthesis of tricyclic chromeno[4,3- b]pyrrolidine frameworks using Baylis–Hillman bromides involving in situ formation of an imine, decarboxylation and a [3+2] cycloaddition sequence is described.

Synthesis, cytotoxic evaluation, and DNA binding of novel thiazolo[5,4- b]quinoline derivatives

A series of novel alkylamino and 9-anilinothiazolo[5,4- b]quinolines were synthesized as potential antitumoral agents. The in vitro cytotoxicity of these compounds was evaluated on several cell lines. The inclusion of electron-withdrawn/acceptor hydrogen-bond groups at position 3′ of the anilino ring and the presence of an alkylamino chain on the tricyclic framework (regardless of its position) seem to be structural features relevant to cytotoxic activity.

Metallotricycle of Lanthanide Supported by a Bridging Diamide: Syntheses and Molecular Structures of {Li(THF)3[LnCl(μ2‐trans‐1,2‐(NSiMe3)2C6H10)(μ2‐Cl)]}2·2THF (Ln=Yb, Nd)

AbstractThe reactions of dilithium salt of trans‐1,2‐bis(trimethylsilylamino)cyclohexane with anhydrous lanthanide trichlorides LnCl3 (Ln=Yb, Nd) in THF afforded the dianionic binuclear tricycles of lanthanide chlorides {Li(THF)3[LnCl(µ2‐trans‐1,2‐(NSiMe3)2C6H10)((2‐Cl)]}2·2THF (Ln=Yb 1, Nd 2) in moderate yields. Both of the bridged complexes were characterized by elemental analysis, IR spectroscopy and single‐crystal X‐ray diffraction. Crystal structural analysis shows that the two complexes are the analogues which have a tricyclic framework built by two bridged lanthanide metals, four nitrogens and four carbons from two diamide ligands. Each lanthanide metal coordinates to three nitrogen atoms and two chlorines to form a distorted trigonal bipyramid and connects with a lithium by a bridging chlorine.

Formal syntheses of (−)- and (+)-aphanorphine from (2 S,4 R)-4-hydroxyproline

We describe the efficient formal syntheses of both natural (−)-aphanorphine and unnatural (+)-aphanorphine from the same commercially available amino acid, (2 S,4 R)-4-hydroxyproline. The tricyclic framework was constructed by intramolecular Friedel–Crafts reaction. (1 R,4 S)-1-Methyl-8-methoxy-3-(4-toluenesulfonyl)-2,3,4,5-tetrahydro-1,4-methano-3-benzazepine ( 8) was synthesized in six steps from sulfonamide 3; (−)-aphanorphine methyl ether 24 was obtained in seven steps from lactone 10. Intramolecular etherification of 18 proceeded with excellent stereoselectivity in the presence of BF 3·OEt 2, which has paved an efficient synthetic route to a series of medicinally attractive heterocycles.

Synthesis of the Tricyclic Core of Colchicine via a Dienyne Tandem Ring-Closing Metathesis Reaction

The synthesis of the tricyclic framework of colchicine has been achieved using a tandem ring-closing metathesis reaction of dienynes as the key step. In this process, both seven-membered rings B and C were formed in one step. Oxidation of tertiary allylic alcohol derived from the tandem metathesis product furnished an intermediate in the total synthesis of colchicine.

Organocatalytic One‐Pot Asymmetric Synthesis of Functionalized Tricyclic Carbon Frameworks from a Triple‐Cascade/Diels—Alder Sequence.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Catalytic Asymmetric Synthesis of Tricyclic Carbon Frameworks

An organocatalytic asymmetric one-pot procedure for the construction of functionalized tricyclic carbon frameworks in good overall yields, high enantioselectivities and diastereoselectivities has been developed. Chiral α,α-diarylprolinol silyl ether 1 mediates a selective Michael reaction of linear aldehydes 2 to aromatic nitroolefins 3 (enamine catalysis) followed by a conjugate addition to α,α-unsaturated aldehydes 4 (iminium catalysis) as well as an intramolecular aldol condensation (enamine catalysis) to give cyclohexene derivates 5. Finally, an intramolecular Diels-Alder reaction in the presence of stoichiometric amounts of dimethylaluminum chloride completes the synthesis of decahydroacenaph­thylenes 6 and decahydrophenalenes 7. Five C-C bonds and eight stereocenters are generated in the four-step process.

Domino Wittig Diels–Alder reaction: an expeditious entry into the AB ring system of furanosesquiterpenes

A domino Wittig Diels–Alder reaction has been employed in delineating a short and flexible synthetic stratagem for ready access to the AB ring system and the tricyclic framework of furanosesquiterpenes, such as the bioactive natural products, furodysin and furodysinin.

Assembly of a planar, tricyclic B4N8 framework with s-indacene structure

A neutral, formally 16pi-electron, tricyclic tetrahydrazidotetraborane was obtained in a two-step procedure involving self-assembly of a dilithiodiborate with B(4)N(8) framework and subsequent oxidation of the phenylborate moieties to boranes and biphenyl using Fe(II) as an oxidant.

Organocatalytic One‐Pot Asymmetric Synthesis of Functionalized Tricyclic Carbon Frameworks from a Triple‐Cascade/Diels–Alder Sequence

Organocatalytic One‐Pot Asymmetric Synthesis of Functionalized Tricyclic Carbon Frameworks from a Triple‐Cascade/Diels–Alder Sequence

5,5′-(Piperazine-1,4-diyl)bis(8-chloropyrido[2,3-b][1,5]benzoxazepine)

The centrosymmetric title compound, C28H20Cl2N6O2, features a tricyclic framework with the characteristic V-shape of the pyridobenzoxazepine nucleus and with the central seven-membered heterocycle having a classical boat conformation. The piperazine ring displays an almost-perfect chair conformation, with the tricyclic nuclei assuming a pseudo-equatorial orientation.

A novel 4‐methylene‐3‐borahomoadamantane: 1,1‐organoboration of an alkyn‐1‐ylsilane using 1‐boraadamantane

Abstract1,1‐Dibromo‐2,2‐bis(trimethylsilylethynyl)ethene (2) reacts with two equivalents of 1‐boraadamantane (1) by 1,1‐organoboration of both trimethylsilylethynyl groups to give a triene 3 bearing two 4‐methylene‐3‐borahomoadamantane moieties in terminal positions. The triene was characterized by one‐ and two‐dimensional 1H, 11B, 13C and 29Si NMR spectroscopy in solution and X‐ray structural analysis in the solid state. The planes of the C double bond are strongly twisted against each other as a result of the bulky substituents, and the surroundings of the boron atoms deviate from the ideal trigonal planar geometry owing to the tension in the tricyclic frameworks. Copyright © 2006 John Wiley & Sons, Ltd.