Friedlander Condensation Research Articles

New Series of Blue-Emitting and Electron-Transporting Copolymers Based on Fluorene

A novel series of conjugated copolymers having oxadiazole, quinoline, quinoxaline, and phenylenecyanovinylene moieties in the main chain based on fluorene were synthesized in good yields by palladium-catalyzed Suzuki coupling reaction, a new approach different from the traditional polyhydrazide precursor route (oxadiazole-containing polymers), acid-catalyzed Friedlander condensation reaction (polyquinolines), and Knoevenagel condensation polymerization (poly(phenylenecyanovinylene)). The thermal, electrochemical, and optical properties of these copolymers were examined. All these polymers possess excellent thermal stability with glass transition temperatures of 114−208 °C and onset decomposition temperatures of 387−415 °C. Cyclic voltammetry studies reveal that these copolymers possess low-lying LUMO energy levels ranging from −3.01 to −3.37 eV and low-lying HOMO energy levels ranging from −6.13 to −6.38 eV and may be promising candidates for electron-transporting or hole-blocking materials in light-emitt...

A convergent total synthesis of mappicine ketone: A leading antiviral compound

An efficient total synthesis of the naturally occuring mappicine ketone 1 and mappicine 2 are described. The approach is based on the assembly of tricyclic amine 5 with pseudo acid chloride 20. A Friedlander condensation is utilized for the construction of the ABC skeleton and a periselective Diels-Alder approach is utilized for the preparation of the pseudo acid chloride.

A Facile Route to Pyrazolo[3,4-b]Pyridines and [1]jbenzopyranoh′[4,3,e]Pyrazolo[3,4-b]Pyridines

A direct synthesis of pyrazolo[3,4-b]pyridines [5&6] and [l]benzopyrano[4′,3′-e]pyrazolo[3,4-b]pyridines (7) is described by Friedlander condensation. An alternative and a short route for the preparation of [l]benzopyrano[4′,3′-e]pyrazolo[3,4-b]pyridines (7) is also reported.

Polyquinolines: Multifunctional Polymers for Electro-Optic and Light-Emitting Applications

ABSTRACTA versatile, and generally applicable modular approach for making second-order nonlinear optical (NLO) side-chain aromatic polyquinolines has been developed. This approach emphasizes the ease of incorporating NLO chromophores onto the pendent phenyl moieties of parent polyquinolines at the final stage via mild Mitsunobu reaction. This method provides the synthesis of polyquinolines with a broad variation of the polymer backbones and great flexibility in the selection of NLO chromophores. These side-chain NLO polyquinolines demonstrate high electro-optic (E-O) activity (up to 35 pm/V at 830 nm and 22 pm/V at 1300 nm, respectively) and a good combination of thermal, optical, electrical and mechanical properties.Comparatively, two new electroluminescent (EL) polyquinolines have been prepared via the Friedlander condensation and nucleophilic reaction. The resulting polymers contain a bipolar property with both an efficient hole-transporting moiety, tetraphenyldiaminobiphenyl (TPD), and an electron affinitive light-emitting moiety, bis-quinoline. In addition, they possess high thermal stability, excellent electrochemical reversibility, good thin film-forming ability, and bright light-emitting property. Electrical characterization of two-layer diode devices based on the configurations of ITO/CuPc/TPD-PQ or TPD-PQE/Al showed excellent electroluminescence performance (a rectification ratio greater than 105 and a low turn-on voltage of less than 4 V).

Total Synthesis of Nothapodytine B and (−)-Mappicine

Concise total syntheses of naturally occurring nothapodytine B (1, mappicine ketone) and (−)-mappicine (3) are detailed. The approach is based on the implementation of a room-temperature, inverse electron demand Diels−Alder reaction of the N-sulfonyl-1-aza-1,3-butadiene 11 for assemblage of a pyridone D ring precursor central to the structure. A Friedlander condensation is utilized for constructing the AB ring system of 1 and 3. An acid-catalyzed reaction sequence is used to accomplish a deprotection with subsequent ring-closure for introduction of the C ring in a single step.

A Modified Friedlander Condensation for the Synthesis of 3-Hydroxyquinoline-2-carboxylates

A Modified Friedlander Condensation for the Synthesis of 3-Hydroxyquinoline-2-carboxylates

Novel A-ring modified camptothecins as topoisomerase I inhibitors

A camptothecin derivative has been prepared wherein the A-ring is fused to an oxazole ring. The compound was prepared via a Friedlander condensation involving benzoxazole 8 and tricyclic ketone 9. This derivative displays potent topoisomerase I inhibition (IC 50 150 nM) when assayed in the ‘cleavable complex’ assay.

A new series of PDGF receptor tyrosine kinase inhibitors: 3-substituted quinoline derivatives.

A series of 63 3-substituted quinoline derivatives has been prepared and tested for inhibition of cell-free platelet derived growth factor receptor tyrosine kinase (PDGF-RTK) activity. The compounds were generally prepared either by a Friedlander condensation between an aryl-acetaldehyde and an o-aminobenzaldehyde or by a palladium-catalyzed coupling between an aryl bromide or triflate and an organostannane or organozinc chloride. The presence of 6,7-dimethoxy groups on the quinoline ring was found to be advantageous although not essential for potent inhibition of PDGF-RTK. A lipophilic group attached to the quinoline 3-position contributed substantially to activity. The lipophilic groups generally consisted of monocyclic aromatics or small alkynyl, alkenyl, and alkyl groups. Optimum activity of ca. < or = 20 nM (IC50) was observed when 6,7-dimethoxyquinoline was substituted in the 3-position with 4-methoxyphenyl (15d), 3-fluoro-4-methoxyphenyl (17m), 3-fluorophenyl (17b), 4-hydroxyphenyl (24), 6-methoxypyridin-3-yl (15o), 5-pyridin-2(1H)-one (23), trans-beta-styryl (15e), thiophene-3-yl (2e), 5-chlorothiophene-2-yl (15f), or cyclopentenyl (17n) groups. Most of the compounds in the series were tested for inhibition of cell-free epidermal growth factor receptor tyrosine kinase activity and found to be inactive.

Convenient synthesis of 2-amino-1,8-naphthyridines, building blocks for host-guest and self-assembling systems

Application of the Reimer-Tiemann reaction to 2,6-diaminopyridine afforded a 26% yield of 2,6-diaminopyridine-3-carboxaldehyde (4) and a small amount (4%) of 2,6-diaminopyridine-3,5-dicarboxaldehyde. Alternatively, conversion of 2,6-diaminopyridine to 2,6-bis(pivaloylamino)pyridine (6), directed lithiation with n-butyllithium, treatment with N-formylmorpholine, and hydrolysis produced (4) in 67% overall yield. The Friedlander condensation of (4) with a variety of activated and unactivated ketones afforded 2-amino-1,8-naphthyridines and bis(2-amino-1,8-naphthyridines) in moderate to good yields, providing a convenient synthesis of useful building blocks for new host-guest and self-assembling systems

Structural features of 1,1'-bis(azaaryl)-substituted ferrocenes

The Friedlander condensation of acetyl- and propionylferrocene with various aromatic o-amino aldehydes results in the formation of azaaryl-substituted ferrocenes. The same reaction carried out on the 1,1'-diacetyl- and 1,1'-dipropionyl analogs provides the corresponding 1,1'-bis(azaaryl)-substituted derivatives. In solution, 1 H NMR shielding effects indicate π-stacking of the azaaryl rings with the pyrido moieties overlapped and pointing in opposite directions

Heteroaromatic fused derivatives of tetracyclo[6.3.0.04,11.O5,9]undecane

A series of rigid syn-orthocyclophanes is prepared by the Friedlander condensation of appropriate o-amino-benzaldehyde derivatives with tetracyclo [6.3.0.0 4,11 .O 5,9 ]undecane-2,7-dione. The reaction may proceed in a stepwise fashion so that unsymmetrical layered compounds can be prepared. These species can be further elaborated by oxidation to quinolinequinones or N-oxides and quaternization to quinolinium salts. Molecular mechanics calculations agree closely with X-ray analysis in describing the structural properties of these cyclophanes. Analysis of the 1 H NMR and UV spectra as well as the reduction potentials of these molecules support a moderate electronic interaction between the decks. Initial investigations regarding their ability to serve as cleft-type hosts are described

2,3; 6,7-Bis (2′,3′-quinolino)tcu: A rigid syn-orthocyclophane

A bis 2,3-quinoline fused derivative of tetracyclo[6.2.1.0.0]undecane is prepared by two sequential Friedlander condensations. An X-ray crystal structure indicates a dihedral angle of 50.5° between the two quinoline rings.

ChemInform Abstract: Polyaza Cavity‐Shaped Molecules. Part 7. Dirhodium Complexes of Triaza and Tetraaza Cavities.

AbstractThe preparation of the cavity‐shaped ligands (VI I), (IX) and (X) involves two sequential Friedlander condensations of (III).

Streptonigrin and related compounds IV. Precursors for the a‐ring

AbstractThe synthesis of streptonigrin or its tricyclic (ABC) analogues by the Friedlander condensation requires a 2‐nitrobenzaldehyde with all the necessary functionalities. A number of alternative syntheses are examined. It is shown that oxidation of 8‐amino‐5,6‐dimethoxy‐2,2‐pyridylquinoline leads to 8‐amino‐2,2‐pyridylqunoline‐5,6‐dione instead of 6‐methoxy‐2,2‐pyridylquinoline‐5,8‐dione. The synthesis of two useful precursors: 4‐bromo‐3‐hydroxy‐5,6‐dimethoxy‐2‐nitrobenzaldehyde and 4‐bromo‐3‐hydroxy‐5‐methoxy‐2‐nitrobenzaldehyde is described.

2,3‐Fused 1,8‐Naphthyridines

AbstractThe Friedlander condensation of 2‐aminonicotinaldehyde with cyclic ketones leads to the preparation of 2,3‐fused 1,8‐naphthyridines. The spectral properties and basicities of these molecules are discussed.

Streponigrin and related compounds. II. Synthesis of the c‐ring precursors

AbstractSynthesis of the tricyclic analogue 1b of the antitumor antibiotic streptonigrin 1a by the application of Friedlander condensation required a substituted 2‐acetylpyridine (2) as the precursor for the C‐ring. A practical, 8‐step sequence was devised for its synthesis starting from 2,5‐lutidine.

Studies in the synthesis of Camptothecin. An efficient synthesis of 2,3-dihydro-1H-pyrrolo(3,4-b)quinoline.

An efficient regioselective synthesis of 2,3-dihydro-1H-pyrrolo[3,4-b]quinoline (3), a key intermediate in the synthesis of camptothecin, has been developed. The synthesis, which has been extended to a number of analogues, involves an acid-catalysed Friedlander condensation in the absence of a solvent. Base-catalysed condensation was shown to lead predominantly to the isomeric 2,3-dihydro-1H-pyrrolo[3,2-b]quinoline (10). The relative stabilities of the enols and enolates derived from N-acetyl-3-pyrrolidone and ethyl 3-oxopyrrolidine-1-carboxylate, intermediates in the synthesis of compounds (3) and (10), are discussed.

The synthesis and some reactions of 2,3‐substituted 1‐phenylbenzo[f]quinoline

AbstractA series of 2,3‐substituted 1‐phenylbenzo[f]quinolines was synthesized by the Friedlander condensation of 1‐benzoyl‐2‐naphthylamine with β‐keto esters. Some chemical transformations of these compounds and the preparation of 13H‐benzo[f]indeno[2,1‐c]quinoline‐13‐one and its 9‐methyl derivative are described.