Synthesis of pyrazolo[3,4-b]pyrrolo[3,4-d]pyridine derivatives via Aza-Diels–Alder reaction: evaluation of torsion effect of pyrazoylimines

A modified method for the synthesis of pyrazolo[3,4-b]pyrrolo[3,4-d]pyridine was developed through an Aza-Diels–Alder reaction of pyrazoylimines with maleimides in the sealed tube. Based on the control experiment, the yields for the Aza-Diels–Alder reaction seemed proportional to the suitable torsion conformation of pyrazoylimine, which was modulated by N,N-disubstituted amidinyl moiety. The versatile sealed tube technique was also proved to promote the higher isolated yields in the Aza-Diels–Alder reaction.     

A general route for the synthesis of pyrimido[4′,5′:4,5]thieno[2,3-c]pyridazine derivatives

Summary A facile synthesis of 8-substituted pyrimido[4,5:4,5]thieno[2,3-c]pyridazines (6a–i) has been accomplished. The sequence involves the ring closure of a heterocyclic aminonitrile precursor (3) after reaction with (dichloromethylene)-dimethylammonium chloride.

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Eine allgemeine Synthese von Pyrimido[4,5:4,5]thieno[2,3-c]pyridazin-Derivaten

Zusammenfassung Es wurde ein einfacher Syntheseweg für 8-substituierte Pyrimido[4,5:4,5]thieno-[2,3-c]pyridazine entwickelt. Die Reaktion verläuft über den Ringschluß eines heterocyclischen Aminonitrilvorläufers (3) nach Umsetzung mit Dichlormethylen-dimethylammoniumchlorid.

     

Structure-property relationships of benzo[2,1-b:3,4-b’]bis[1]benzothiophenes for organic field effect transistors

A series of novel benzo[2,1-b:3,4-b’]bis[1]-benzothiophene (BBBT) derivatives with different side-chains were synthesized and characterized. And their mobility properties were evaluated based on their active layers in OFETs devices. By means of simple thermal annealing, the devices based on BBBT-4 and BBBT-6 exhibited typical p-type FETs behavior with average hole mobilities of 0.28 and 0.124?cm² V^?1?s^?1, respectively. Furthermore, the structure-property relationships of these semiconductors were also investigated by XRD and AFM.     

A novel three-component method for the synthesis of spiro[chromeno [4′,3′:4,5] pyrimido[1,2-b] indazole-7,3′-indoline]-2′,6(9H)-dione

A green, efficient, and rapid procedure for the synthesis of novel spiro[chromeno[4′,3′:4,5] pyrimido[1,2-b]indazole-7,3′-indoline]-2′,6(9 H)-dione derivatives has been developed by one-pot condensation of 4-hydroxy-2H-chromen-2-one, isatin, and 1H-indazole-3-amine, in the presence of acetic acid in EtOH. This method has the advantages of operational simplicity, and high yield of products via a simple experimental and work-up procedure as compared to the conventional methods. The reaction mechanism and substrate scope of this novel reaction is briefly discussed.     

Green metal-free synthesis of spiro-fused 3,4′-pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyrimidine derivatives via deamination cyclization reactions in aqueous medium

Research on Chemical Intermediates - A green metal-free synthesis of spiro-fused 3,4′-pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyrimidine derivatives via deamination cyclization reactions...     

Application of ortho-chloro-β-aroylthioamides in synthesis(II): an efficient one-pot, three-component synthesis of tricyclic thiochromeno[2,3-b]pyridine derivatives

Tricyclic thiochromeno[2,3-b]pyridine derivatives have been successfully synthesized in an unusual one-pot multicomponent cascade reaction from ortho-halo-β-aroylthioamides, Meldrum's acid, and aromatic aldehydes. The reaction presumably proceeds via Knoevenagel condensation-Michael addition-cyclocondensation-decarboxylation-rearrangement-intramolecular S_NAr reaction sequence. High bond forming efficiency of this reaction makes it attractive for the synthesis of thiochromeno[2,3-b]pyridine derivatives in a single step operation.     

Microwave assisted synthesis of 2-aminooxazolo [4,5-b] pyridine derivatives via intramolecular C–O bond formation in aqueous medium

A highly, efficient synthetic protocol for the synthesis of 2-aminooxazolo[4,5-b]pyridine derivatives is established via intramolecular C–O bond coupling using copper iodide as a catalyst and water as solvent. A variety of functionalized substrates were found to react under this reaction conditions to provide products in good to excellent yields.     

Microwave-assisted synthesis of pyrazolo[3,4-b]pyridine-spirocycloalkanediones by three-component reaction of 5-aminopyrazole derivatives, paraformaldehyde and cyclic β-diketones

New pyrazolo[3,4-b]pyridine-5-spirocycloalkanedione derivatives were prepared via three-component reaction between 5-(4-R-benzylamino)pyrazoles, cyclic β-diketones and paraformaldehyde. The use of indandione as β-diketone resulted in the formation of two products, the pyrazolo[3,4-b]pyridine-5-spiroindanediones and 3-tert-butyl-1-phenylindeno[2,3-e]pyrazolo[3,4-b]pyridine. The structures of the pyrazolo[3,4-b]pyridine-5-spirocycloalkanedione were confirmed by single-crystal X-ray diffraction. This protocol provides a simple one-step synthetic methodology with the advantages of easy work-up, mild reaction conditions and environmentally benign.     

Efficient and mild one-pot synthesis of (E)-8′-arylidene-5′,6′,7′,8′-tetrahydrospiro[oxindole-3,4′-pyrano[3,2-c]pyridin] derivatives with potential antitumor activity

A mild and efficient cyclization procedure for the synthesis of (E)-8′-arylidene-5′,6′,7′,8′-tetrahydrospiro[oxindole-3,4′-pyrano[3,2-c]pyridin] derivatives was achieved via one-pot three-component condensation of isatins, malononitrile and (E)-3-arylidene-1-methylpiperidin-4-ones using piperidine as an efficient catalyst and ethanol as an environmentally benign solvent. The in vitro antitumor activity of these compounds was evaluated in human cervical carcinoma cell line (Hela), human liver hepatocellular carcinoma cell line (HepG2), and human breast carcinoma cell line (MDA-MB-231).     

A practical and expeditious method for the preparation of the potential anticancer agent 5,6,11,12,17,18,23,24-octahydrocyclododeca[1,2-b:4,5-b′:7,8-b″:10,11-b?]tetraindole (CTet)

A new synthetic method to obtain the potential anticancer agent 5,6,11,12,17,18,23,24-octahydrocyclododeca[1,2-b:4,5-b′:7,8-b′′:10,11-b′′′]tetraindole (CTet), starting from 1H-indole-3-carboxaldehyde and sulfamide, is described. Although a mixture of CTet and cyclic indole trimer (CTr) is formed, higher CTet/CTr ratio (4:6) and CTet yield (15%) make our protocol more favorable than those reported in the literature. A discussion on the possible reaction mechanism is reported.     

Azido–tetrazole tautomerism of pyrano[3,4-c]pyridine derivatives

Russian Journal of Organic Chemistry - Treatment of N-aryl-8-hydrazinylpyrano[3,4-c]pyridine-5-carbonitriles with sodium nitrite in acetic acid afforded the corresponding 8-azido derivatives...     

A new method for the formation of the imidazo[4′, 5′; 3,4] pyrido[2,3-b]indole ring: Formal synthesis of the alkaloids from marine origin grossularines-1 and 2

A new synthesis of the 2-dimethylamino-4-hydroxy-6-methoxymethyl-3H-imidazo[4′, 5′:3,4] pyrido[2,3-b]indole, used as key intermediate in the total synthesis of the alkaloids grossularines-1 and -2, based on the step-wise formation of the pyridine and imidazole rings, is described.     

Synthesis of new pyrido[2′,3′:3,4]pyrazolo[5,1-c]-[1,2,4]triazin-4(6H)-one derivatives

Russian Chemical Bulletin - New pyrido[2′,3′:3,4]pyrazolo[5,1-c][1,2,4]triazin-4(6H)-one derivatives were synthesized from accessible 1,2,4-triazine and pyrazolo[5,1-c][1,2,4]triazine...     

2-Allyl-N-benzyl substituted α-naphthylamines as building blocks in heterocyclic synthesis. New and efficient syntheses of benz[e]naphtho[1,2-b]azepine and naphtho[1,2-b]azepine derivatives

A new series of 13-acetyl-7,12-dihydro-7-ethylbenz[e]naphtho[1,2-b]azepine (4a-d) and 2-aryl-4-hydroxy-2,3,4,5-tetrahydronaphtho[1,2-b]azepine derivatives (6a-d) have been synthesized from N-allyl-N-benzyl substituted α-naphthylamines (1a-d) by utilizing aromatic amino-Claisen rearrangement, intramolecular Friedel-Crafts alkylation and intramolecular dipolar 1,3-cycloaddition nitrone-olefin reactions.     

Synthesis of Certain 3-Aminopyrazolo[5,4-b]pyridine and 3,4-Substituted Pyrido[2′,3′：3,4]pyrazolo[5,1-c][1,2,4]triazine Derivatives

2-Thioxo-1,2-dihydropyridine derivatives 2a, 2b were reacted with methyl iodide to give 2-methylthiopyridines 3a, 3b, which were reacted with hydrazine hydrate to produce 3-aminopyrazolo[5,4-b]pyridines 4a, 4b. Compounds 4a, 4b were diazotized to afford the corresponding diazonium salts 5a, 5b, which were reacted with some active methylene compounds 6a-6h to give the corresponding pyrido[2′,3′ ： 3,4]pyrazole[5,1-c][1,2,4]triazines 7-14.     

Synthesis of new pyridazino[4′,3′:4,5]-thieno[3,2-d]-1,2,3-triazine and pyrimido[4′,5′:4,5]thieno[2,3-c]pyridazine derivatives

Summary 8,9-Diphenylpyridazino[4,3:4,5]thieno[3,2-d]-1,2,3-triazin-4(3H)-one (2), 3-substituted 8,9-diphenylpyridazino[4,3:4,5]thieno[3,2-d]-1,2,3-triazin-4(3H)-ones (3a–c), 3,4-diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazin-8(7H)-one (4), 8-chloro-3,4-diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazine (5), 8-substituted 3,4-diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazines (6a–h) and 7-substituted 3,4-diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazin-8(7H)-ones(7a–c) were synthesized from 5-amino-3,4-diphenylthieno[2,3-c]pyridazine-6-carboxamide (1).

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Synthese neuer Pyridazino[4,3:4,5]thieno[3,2-d]-1,2,3-triazin-und Pyrimido[4,5:4,5]thieno[2,3-c]pyridazin-Derivate

Zusammenfassung Folgende Verbindungen wurden ausgehend von 5-Amino-3,4-diphenylthieno[2,3-c]pyridazin-6-carboxamid (1) synthetisiert: 8,9-Diphenylpyridazino[4,3:4,5]thieno[3,2-d]-1,2,3-triazin-4(3H)-on (2), 3-substituierte 8,9-Diphenylpyridazino[4,3:4,5]thieno[3,2-d]-1,2,3-triazin-4(3H)-one (3a–c), 3,4-Diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazin-8[7H]-on (4), 8-Chlor-3,4-diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazin (5), 8-substituierte 3,4-Diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazine (6a–h) und 7-substituierte 3,4-Diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazin-8(7H)-one (7a–c).