bluuebunny/crossref_metadata_2025_split huggingface dataset:
The reactions of heterocyclic isothiocyanates bearing an ortho ester group with aminoalcohols
Authors: Urleb Uroš 
Published: March 2009

AbstractHeterocyclic isothiocyanates 1,5,9, bearing an o‐ester group were converted to thiourea derivatives 2a‐c, 6a‐b, and 10a‐b, respectively, using β‐aminoalcohols, and to the fused ring systems, e.g., thieno[3,2‐d]pyrimidine 4a‐b, pyrido[2,3‐d]pyrimidine 8, pteridine 11a, thiazolo[3,2‐a]pyrido[2,3‐d]pyrimidine 7a‐b, and thiazolo[3,2‐a]mieno[3,2‐d]pyrirnidine 3a‐c, derivatives.
Synthesis and antibacterial activity of 1‐(substituted‐benzyl)‐6‐fluoro‐1,4‐dihydro‐4‐oxoquinoline‐3‐carboxylic acids and their 6,8‐difluoro analogs
Authors: Sheu Jia‐Yuh , Chen Yeh‐Long , Fang Kuo‐Chang , Wang Tai‐Chi , Tzeng Cherng‐Chyi , Peng Chien‐Fang 
Published: March 2009

AbstractAlkylation of 6,7‐difluoro‐4‐hydroxyquinoline‐3‐carboxylic acid ethyl ester with substituted‐benzyl chlorides gave 1‐(substituted‐benzyl)‐6,7‐difluoro‐1,4‐dihydro‐4‐oxoquinoline‐3‐carboxylic acid ethyl esters. Their treatment with piperazine or N‐methylpiperazine in pyridine yielded 1‐(substituted‐benzyl)‐6‐fluoro‐1,4‐dihydro‐4‐oxo‐7‐(l‐piperazinyl)quinoline‐3‐carboxylic acid ethyl esters which were hydrolyzed with aqueous sodium hydroxide and then acidified with hydrochloric acid afforded the desired 1‐(substituted‐benzyl)‐6‐fluoro‐1,4‐dihydro‐4‐oxo‐7‐(1‐iperazinyl)quinoline‐3‐carboxylic acids. The 6,8‐difluoro analogs were prepared similarly using 6,7,8‐trifluoro‐4‐hydroxyquinoline‐3‐carboxylic acid ethyl ester as a starting material. Some of these quinolones demonstrated fairly good antibacterial activities. Among them, 6‐fluoro‐1‐(4‐fluorophenylmethyl)‐1,4‐dihydro‐7‐(1‐iperazinyl)‐4‐oxoquinoline‐3‐carboxylic acid (7d) and 6,8‐difluoro‐1‐(3‐fluorophenylmethyl)‐1,4‐dihydro‐7‐(1‐piperazinyl)‐4‐oxoquinoline‐3‐carboxylic acid (8c) are two of the best.
New supramolecular transition metal catalysts
Authors: Reetz Manfred T. 
Published: March 2009

AbstractThe covalent connection of a catalytically active transition metal center with a water‐soluble receptor (host molecule) generates a new type of supramolecular catalyst in which the features of molecular recognition, phase transfer catalysis and transition metal catalysis are combined in a single system. The first examples of this principle make use of commercially available β‐cyclodextrin (β‐CD) as the receptor and rhodium complexes of diphosphanes as the catalytically active center, these being covalently connected to one another via a spacer. In competitive hydrogenation of certain olefins, unusual degrees of substrate selectivity based on molecular recognition are observed, not possible by conventional transition metal catalysts. The two‐phase (water/organic) hydrogenation of nitro‐aromatics also is a smooth process catalyzed by these supramolecular complexes. They also constitute an unusually active catalyst system for the selective hydroformylation of higher olefins such as 1‐octene in a two‐phase system. Dendrimers having diphosphane moieties on the surface provide ligands for transition metals, the corresponding metal complexes (e.g., Pd) functioning as efficient catalysts which can be recycled due to their nanoscopic properties.
Synthesis, characterization and in vitro anthelmintic activity against Nippostrongylus brasiliensis of new 5‐aryl‐2‐phenyl‐6,7‐dihydropyrazolo[1,5‐a]pyrimidines
Authors: Quiroga Jairo , Insuasty Braulio , Hormaza Angelina , Gamenara Daniela , Dominguez Laura , Saldaña Jenny 
Published: March 2009

AbstractSeveral new pyrazolo[1,5‐a]pyrimidines were obtained from the reaction of 1H‐5‐amino‐3‐phenylpyrazole (1) with β‐dimethylaminopropiophenones 2 in pyridine. The structure elucidation of 6,7‐dihydropyrazolo[1,5‐a]pyrimidines 3 is based on nmr measurements. These compounds showed moderate anthelmintic in vitro activity against the Nipposirongylus brasiliensis model.
Haloacetylated enol ethers. 13. Synthesis of N‐[1‐aryl(alkyl)‐3‐oxo‐4,4,4‐trichloro‐1‐buten‐1‐yl]‐o‐phenylenediamines and 2‐trichloromethyl‐4‐aryl‐3H‐1,5‐benzodiazepines
Authors: Bonacorso Helio Gauze , Bittencourt Sandra R. T. , Wastowski Arci D. , Wentz Alexandre P. , Zanatta Nilo , Martins Marcos A. P. 
Published: March 2009

AbstractThe synthesis and isolation of the intermediates N‐[1‐aryl(alkyl)‐3‐oxo‐4,4,4‐trichloro‐1‐buten‐1‐yl]‐o‐phenylenediamines 2a‐f and the corresponding 2‐trichloromethyl‐4‐aryl‐3H‐1,5‐benzodiazepines 3c‐g or benzimidazoles 4a‐b derivatives obtained from the intramolecular cyclization of 2a‐f or from direct cyclo‐condensation reaction of β‐alkoxyvinyl trichloromethyl ketones 1a‐g with o‐phenylenediamine, is reported. Depending of the structure of the β‐alkoxyvinyl trichloromethyl ketones or the N‐[1‐aryl(alkyl)‐3‐oxo‐4,4,4‐trichloro‐buten‐1‐yl]‐o‐phenylenediamines and the reactions conditions, benzimidazoles or 3H‐1,5‐benzodiazepines were obtained.
Synthesis and characterization of some heterocyclic derivatives from 1,2:3,4‐Di‐o‐isopropylidene‐α‐d‐galacto‐1,6‐hexadialdo‐1,5‐pyranose oxime
Authors: Alho M. A. Martins , D'accorso N. B. 
Published: March 2009

AbstractWe report the synthesis of 5‐[5′‐(1′,2′:3′,4′‐di‐O‐isopropylidene‐β‐L‐arabinopyranosyl)]tetrazole, from 1,2:3,4‐di‐O‐isopropylidene‐α‐D‐galacto‐1,6‐hexodialdo‐1,5‐pyranose oxime via 1,2:3,4‐di‐O‐isopropylidene‐α‐D‐galcturononitrile as intermediate by 1,3‐dipolar cycloaddition. We also report the synthesis of 5‐methyl‐ and 5‐phenyl‐2‐[5′‐(1′,2′:3′,4′‐di‐O‐isopropylidene‐β‐L‐arabinopyranosyl)]‐1,3,4‐oxadiazole from the tetrazole derivative.The physical and spectroscopic characterizations of the heterocyclic derivatives as well as the intermedi ate nitrile and the principal by product are described and we discuss its possible formation pathway. We present the preferential conformation in solution using computational calculation and spectroscopic data.
Synthesis and anticonvulsant activity of 3‐[3‐[(dimethylamino)‐methyl]‐5‐methyl‐4H‐1,2,4‐triazol‐4‐yl]‐4‐(o‐chlorobenzoyl)pyridine
Authors: Arora Vinod K. , Knaus Edward E. 
Published: March 2009

AbstractWolff‐Kishner reduction of 3‐amino‐4‐(o‐chlorobenzoyl)pyridine (3) afforded 3‐amino‐4‐(o‐chlorobenzyl)pyridine (5), which on subsequent reaction with triethyl orthoformate and then acetyl hydrazide yielded 1‐acetyl‐2‐[N‐[4‐(o‐chlorobenzyl)pyridin‐3‐yl]formimidoyl]hydrazone (7). Cyclization of hydrazone 7 gave 3‐(3‐methyl‐4H‐1,2,4‐triazol‐4‐yl)‐4‐(o‐chlorobenzyl)pyridine (8), which on Jones oxidation yielded 3‐(3‐methyl‐4H‐1,2,4‐triazol‐4‐yl)‐4‐(o‐chlorobenzyl)pyridine (9). The Mannick reaction of 3‐(3‐methyl‐4H‐l,2,4‐triazol‐4‐yl)‐4‐(o‐chlorobenzyl)pyridine (9) with aqueous formalin and dimethylamine hydrochloride afforded 3‐[3‐[(dimethylamino)methyl]‐5‐methyl‐4H‐1,2,4‐triazol‐4‐yl]‐4‐(o‐chlorobenzoyl)‐pyridine (10). 3‐[3‐[(Dimethylamino)methyl]‐5‐methyl‐4H‐1,2,4‐triazol‐4‐yl]‐4‐(o‐chlorobenzoyl)pyridine (10) exhibited good anticonvulsant activity in the subcutaneous pentylenetetrazole anticonvulsant screen indi cating that an appropriately substituted‐pyridine ring moiety can serve as a bioisostere of a chlorobenzene ring with respect to anticonvulsant activity.
Methanetricarboxylates as key reagents for the simple preparation of heteroarylcarboxamides with potential biological activity. Part 2. Reaction of methanetricarboxylates with 2‐aminopyridine, 2‐aminopyrimidine, 2‐aminothiazole and 2‐aminobenzothiazole
Authors: Kutyrev Alexander , Kappe Thomas 
Published: March 2009

AbstractThe reaction of methanetricarboxylates 1a,b with 2‐aminopyridine, 2‐aminopyrimidine, 2‐aminothiazole as well as 2‐aminobenzothiazole yields corresponding heteroarylcarboxylic acid esters 2a,b, 5, 8, 11a,b. These heterocyclic esters were used as a starting material by the reaction with primary amines to obtaining a number of heteroarylcarboxylic amides 4a‐j, 6, 10a,b, 13a‐g bearing various substituents on the carboxamide group.
Novel cyclization reactions of mono‐ and dichloroazodienes. A new synthesis of substituted pyridazines
Authors: South Michael S. 
Published: March 2009

AbstractCyclization of the in—situ generated chloroazodienes with a variety of enamines was found to give chloro‐substituted tetrahydropyridazines which could be aromatized to pyridazines by base treatment. This sequence appears to be a formal 4 + 2 hetero Diels‐Alder reaction with a high degree of regio and stereo control and constitutes a new synthesis of substituted pyridazines. However, cyclization of the corresponding dichloroazodienes with acyclic enamines gave not only the expected pyridazine product, but also gave an N‐aminopyrrole product. Combination of the dichloroazodiene with cyclic enamines gave bicyclic dihy‐dropyridazines, bicyclic pyridazines, and acyclic enamines which could be forced to close to the bicyclic dihydropyridazines upon further heating. These results would indicate a stepwise mechanism. The scope and mechanistic speculations on these reactions will be presented.While exploring the novel cyclization reactions of 4‐chloroazodienes with electron rich olefins we developed a new and general synthesis of substituted 3‐phenypyridazines. A number of these analogs were found to exhibit bleaching herbicidal activity (phytoene desaturase inhibition). Further methodology development coupled with analog synthesis led to the preparation of 3‐heteroaryloxy and 3‐aryloxypyridazines with increased unit activity and selectivity as well as good environmental properties. These compounds were found to be more active than current commercial standards on a number of important weed species with selectivity in corn in the US and small grains in Europe. Greenhouse activity of the most active analogs ranged from 17–140 g/hectare on important narrow‐leaf species.
Synthesis of novel pyrano fused quinolones, coumarins, and pyridones
Authors: Toche R. B. , Jachak M. N. , Sabnis R. W. , Kappe T. 
Published: March 2009

AbstractDedicated to Professor Dr. Hans Junek, Graz, on the occasion of his 70th birthday A novel efficient synthesis of pyrano fused heterocycles namely, pyrano[3,2‐c]quinoline‐2,5(6H)‐diones 3a‐e, 7b‐d, pyrano[3,2‐c]benzopyran‐2,5(6H)‐dione (7f), and pyrano[3,2‐c]pyridine‐2,5(6H)‐diones 10, 11 was achieved by the condensation of 4‐hydroxy‐2‐(1H)‐quinolones 1a‐e, 4‐hydroxycoumarin (1f), or 4‐hydroxy‐2(1H)‐pyridone (9) with α‐acetyl‐γ‐butyrolactone (2) or the sodium salt of α‐formyl‐γ‐butyrol‐actone (6), respectively, in the presence of ammonium acetate.
A new domino reaction based on [4+2]‐cycloadditions of pyrido[1,2‐a]pyrazines with azadienophiles
Authors: Billert Thomas , Beckert Rainer , Brandenburg Jörg , Fehling Peer , Döring Manfred , Görls Helmar , Langer Peter 
Published: March 2009

AbstractThe reaction of pyrido[1,2‐a]pyrazines 1 with nitroso compounds 2 provides pyridyl substituted 1,2,4‐triazinones 4 via a domino reaction which involves a cycloaddition and a ring transformation reaction. The intermediate and regioselective formed oxadiazines 4′ were trapped by complexation yielding the (CO)4Mo‐complex 5. Derivatives of diazene such as N‐phenyltriazolindione 6a, phthalazinedione 6b or esters of azodicarboxylic acid 6c‐6f reacted with 1 to give different derivatives of 1,2,4‐triazine 7a‐f. The use of oxygen gave oxadiazinones 8.
Reaction of 4,5‐diamino‐3‐methyl‐1‐phenylpyrazole with 3‐dimethylaminopropiophenones. Synthesis of new 4‐aryl‐6‐methyl‐8‐phenyl‐2,3‐dihydropyrazolo[3,4‐b]diazepines and 4‐aryl‐8‐methyl‐6‐phenyl‐2,3‐dihydropyrazolo[4,3‐b]diazepines
Authors: Insuasty O Braulio , Insuasty I Henry , Quiroga P Jairo , Saitz Claudio , Jullian Carolina 
Published: March 2009

AbstractNew 4‐Aryl‐6‐methyl‐8‐phenyl‐2,3‐dihydropyrazolo[3,4‐b]diazepines and 4‐aryl‐8‐methyl‐6‐phenyl‐2,3‐dihydropyrazolo[4,3‐b]diazepines were obtained from the reaction of 4,5‐diamino‐3‐methyl‐1‐phenylpyrazole 1 with one equivalent of the 3‐dimethylaminopropiophenones 2 in absolute ethanol. The structures of 4‐aryl‐6‐methyl‐8‐phenyl‐2,3‐dihydropyrazolo[3,4‐b]diazepines 3 and 4‐aryl‐8‐methyl‐6‐phenyl‐2,3‐dihydropyrazolo[4,3‐b]diazepines 4 were determined by detailed nmr measurements.
Catalytic hydrogenation of 3‐benzyloxycarbonylaminoazino[1,2‐x]‐azin‐4‐ones. A facile access to 3‐amino‐6,7,8,9‐tetrahydro‐4H‐pyrido[1,2‐a]pyridin‐4‐ones and 3‐Amino‐6,7,8,9‐tetrahydro‐4H‐azino[1,2‐x]pyrimidin‐4‐ones
Authors: Rečnik Simon , Toplak Renata , Svete Jurij , Pizzioli Lucija , Stanovnik Branko 
Published: March 2009

AbstractBy catalytic hydrogenation of 3‐(benzyloxycarbonyl)amino‐4H‐pyrido[1,2‐a]pyridin‐4‐ones 28 and 29, and azino[1,2‐x]pyrimidin‐4‐ones 32–35, 41, and 42, partial saturation of the heterocyclic systems and removal of the benzyloxycarbonyl moiety was observed to give 3‐amino‐6,7,8,9‐tetrahydro‐4H‐pyrido[1,2 a]pyridin‐4‐ones 30 and 31, and 3‐amino‐6,7,8,9‐tetrahydro‐4H‐azino[1,2‐x]pyrimidin‐4‐ones 36–39, 43, and 44 in high yields. The methods represent a simple two step synthesis, starting from heterocyclic α‐amino compounds and methyl (Z)‐2‐(benzyloxycarbonyl)amino‐3‐dimethylaminopropenoate followed by catalytic hydrogenation.
Ring transformations of heterocyclic compounds. XX Benzo‐fused spiro[cyclohexadiene‐dihydroindoles] by ring transformation of pyrylium salts with anhydrobases of benzo[e]‐ and benzo[g]indolium salts
Authors: Zimmermann Thomas 
Published: March 2009

AbstractThe diastereoselective synthesis of 6‐aroyl‐3,5‐diarylspiro[cyclohexa‐2,4‐diene‐1,2′2′,3′‐dihydro‐1′H‐benzo[e]indoles] 6 and ‐benzo[g]indoles] 7 from 2,4,6‐triarylpyrylium perchlorates 1 and in situ generated 2‐methylene‐2,3‐dihydro‐1H‐benzo[e]indoles 3 or ‐benzo[g]indoles 5 (anhydrobases of the corresponding 2‐methyl‐1H‐benzo[e]indolium perchlorates 2 and 2‐methyl‐3H‐benzo[g]indolium perchlorates 4, respectively) in the presence of triethylamine/acetic acid in ethanol by a 2,5‐[C4+C2] pyrylium ring transformation is reported. Spectroscopic data of the transformation products and their mode of formation are discussed.
Inverse electron demand diels‐alder reactions of psoralens. Synthesis and mass spectra of novel pyridazinocoumarins
Authors: González José Carlos , Dedola Teresa , Santana Lourdes , Uriarte Eugenio , Begala Michela , Copez Debora , Podda G. 
Published: March 2009

AbstractDiels‐Alder reactions between the furan double bond of 8‐methoxypsoralen and 1,2,4,5‐tetrazine or 3,6‐bistrifluoromethyl‐1,2,4,5‐tetrazine were accompanied by the release of diatomic nitrogen and the opening of the furan ring to leave a 6‐pyridazinocoumarin. When 3,6‐bis(methoxycarbonyl)‐1,2,4,5‐tetrazine was used as diene with 8‐methoxy‐, 5‐methoxy‐ or 8‐hydroxypsoralen as substrate a previously unknown heterocyclic framework was created. Formation of the fourth ring was accompanied by conversion of the furan ring to a pyrone, presumably by intramolecular transestenfication with release of methanol. The characterization of the products of these reactions by exhaustive mass spectrometric analysis is discussed.
An efficient route for synthesis of 5,6‐diphenylimidazo‐[2,1‐b]thiazoles as antibacterial agents
Authors: Hozien Zeinab A. , Abd El‐Wareth A. O. Sarhan , El‐Sherief Hassan A. H. , Mahmoud Abdalla M. 
Published: March 2009

AbstractThe reaction of 4,5‐diphenylimidazol‐2‐thione (1) with aromatic ketones 2a‐i using the acidified acetic acid method afforded the 4,5‐diphenyl(2‐imidazolylthio)acetophenones 3a‐h in good yields. While, the cyclized product 4i was obtained directly upon reaction of 1 with α‐acetyl naphthalene. Compounds 3a‐h were cyclized directly to the corresponding 3‐aryl‐5,6‐diphenylimidazo[2,1‐b]thiazoles (4a‐c) and (4e‐h). In the same manner the reaction of 1 with aliphatic and/or alicyclic ketones gave the 3‐(4,5‐diphenyl‐2‐imidazolylthio)acetone derivatives 5a‐d, 2‐(4,5‐diphenylimidazolylthio)cycloalkanones 8a,d and the tricyclic compounds 9b‐c respectively. The cyclized compounds 6a‐d and 9a,d were obtained by cyclization of 5a‐d and 8a,b respectively. Oxidation of 1 gives the corresponding bis(4,5‐diphenyl‐2‐imidazolyl)‐disulfide (10) in 90% yield. Some of the synthesized compounds were tested for antifungal and antibacterial activity.
Convenient synthesis of 1,2,3,4‐tetrahydro‐pyrimidin‐5‐ylbenzoxazoles
Authors: Jung Myung Hee , Choi Sung‐Won , Cho Kui‐Woong 
Published: March 2009

Abstract2‐Pyrimidin‐5‐ylbenzoxazoles 7 have been synthesized by condensation of 5‐pyrimidinecarboxaldehyde 4 with substituted aminophenols 5 followed by oxidative cyclization of the resulting Schiff's bases 6 with iodobenzene diacetate. Subsequent formation of methylpyrimidinium salts 8 and reduction thereafter afforded tetrahydropyrimidinylbenzoxazoles 10. This method has been utilized in the synthesis of M1 muscarinic agonist candidates.
Reactions of 6‐aminopyrimidines with 2‐dimethylaminomethylenetetralone. Regiospecific Synthesis Of 5,6‐Dihydrobenzo [h]pyrimido [4,5‐b] quinolines
Authors: Quiroga Jairo , Insuasty Braulio , Insuasty Henry , Abonia Rodrigo , Ortíz Antonio , Sánchez Adolfo , Nogueras Manuel 
Published: March 2009

AbstractBenzo[h]pyrimido[4,5‐b]quinolines (3) have been synthesized via a regiospecific cyclocondensation reaction between 6‐aminopyrimidines (1) and 2‐dimethylaminomethylentetralone hydrochloride (2). The linear structure of the final compounds were determined by nmr measurements, especially by 1H,1H, 1H,13C COSY and DEPT experiments.
Synthesis of chiral fused heterocyclic compounds containing 1,2,4‐triazole ring
Authors: Shi Haoxin , Wang Zhongyi , Shi Haijian 
Published: March 2009

AbstractA series of new chiral (S)‐3‐ary1‐6‐pyrrolidin‐2‐yl‐[1,2,4]triazolo[3,4‐b]thiadiazole (II1‐5), (S)‐1‐(3‐aryl‐[1,2,4]triazolo[3,4‐b][1,3,4]thiadiazol‐6‐yl)‐ethylamine (II6‐8) and (S)‐1,2‐bis(3‐aryl‐[1,2,4]triazolo‐[3,4‐b][1,3,4]thiadiazol‐6‐yl)‐ethylamine (II9‐11) were prepared by the condensation of 3‐aryl‐4‐amino‐5‐mercapto‐1,2,4‐triazoles with different L‐amino acids in the presence of phosphorus oxychloride and evaluated for their antibacterial activity.
Synthesis and potential central nervous system stimulant activity of 5,8‐methanoquinazolines and bornano‐triazines fused with imidazole and pyrimidine
Authors: Nagai Shinichi , Miyachi Takamasa , Nakane Tetsu , Ueda Taisei , Uozumi Yasuhiro 
Published: March 2009

AbstractStarting from 3‐chloro‐5,8‐methanoquinazoline 1 and 3‐chloro‐bornano[1,2,4]triazine 7, the novel 5,8‐methanoquinazolines 5a‐b and bornano[1,2,4]triazines 10a‐b fused with imidazole and pyrimidine were prepared. None of these compounds showed any satisfactory central nervous system stimulant activities.
New synthesis of oxindole‐1‐carboxamides
Authors: Porcs‐Makkay Marta , Simig Gyula 
Published: March 2009

AbstractA new synthesis of oxindole‐1‐carboxamides was elaborated by the reaction of oxindole‐1‐phenyl‐carboxylate with various amines. This method also permitted the preparation of N,N‐disubstituted oxindole‐1‐carboxamides.
Intramolecular catalysis of aminolysis of phosphorus heterocycles incorporating an α‐aminoamide moiety. III. Synthesis of 2‐oxo or 2‐thioxo 1,3‐disulfonyl‐1,3,2‐diazaphospholidines and reactions with amines and alcohols
Authors: Dujols Frédéric J. M. , Mulliez Michel E. 
Published: March 2009

AbstractA series of 2‐oxo or 2‐thioxo 1,3‐disulfonyl‐1,3,2‐diazaphospholidines 4was prepared by condensation of phosphonyl dichlorides 2 with bis‐N,N'‐sulfonylethylenediamines 1 in pyridine. Complete aminolysis or alcoholysis of heterocycles 4 took place with regeneration of sulfonyldiamines 1. These reactions are very sensitive to steric hindrance, and hydrolysis is generally favoured over aminolysis. The results are discussed in terms of mechanisms of phosphorylation.
Preparation and reactions of pyridinyl tellurides
Authors: Shilai Manabu , Uchiyama Masanobu , Kondo Yoshinori , Sakamoto Takao 
Published: March 2009

AbstractTellurium‐metal exchange reaction of n‐butyl 2‐pyridinyl telluride derivatives with n‐butyllithium or dilithium dimethylcyanocuprate proceeded smoothly to give the corresponding 2‐pyridinylmetal derivatives, which are important intermediates for functionalization of pyridines.
Studies on uracils: A facile one‐pot synthesis of pyrazolo[3,4‐d]pyrimidines
Authors: Bhuyan P. J. , Borah H. N. , Lekhok K. C. , Sandhu J. S. 
Published: March 2009

AbstractThe reaction of 6‐hydrazino uracils 1 and nitrones 2 result in an efficient one‐pot synthesis of pyrazolo[3,4‐d]pyrimidines 3 in excellent yields. The isolation of the by‐product aniline from the reaction mixture supported the plausible mechanism for the formation of pyrazolo[3,4‐d]pyrimidines.
An improved synthesis of 5,6,7,8‐tetrahydro‐1,7‐naphthyridine ‐ a conformationally‐restricted analog of 2‐(3‐pyridyl)ethylamine
Authors: Dow Robert L. , Schneider Steven R. 
Published: March 2009

AbstractThe 5,6,7,8‐tetrahydro‐1,7‐naphthyridine (7) pharmacophore has the potential to serve as a confor‐mationally‐locked analog of the pharmacologically active 2‐(3‐pyridyl)ethylamine (1) core structure. This paper describes the synthesis of 5,6,7,8‐tetrahydro‐1,7‐naphthyridine (7) via a five‐step sequence, which affords a significant improvement over previously reported syntheses.
Reaction of 3‐substituted and 4‐bromo‐3‐substituted isoquinolin‐1‐(2h)‐ones with propargyl bromide
Authors: Usifoh Cyril Odianose 
Published: March 2009

AbstractIsoquinolinones were brominated using N‐bromosuccinimide in dimethylformamide at room temperature to give 4‐bromo‐3‐substituted isoquinolin‐1‐(2H)‐ones. The reaction of these isoquinolinones with propargyl bromide in the presence of anhydrous potassium carbonate yielded N and O‐alkylated products.
A convenient synthesis of pyrazolidine and 3‐amino‐6,7‐dihydro‐1H,5H‐pyrazolo[1,2‐a] pyrazol‐1‐one
Authors: Boros Eric E. , Bouvier Frédéric , Randhawa Sab , Rabinowitz Michael H. 
Published: March 2009

AbstractA convenient four‐step synthesis of the aminobicyclopyrazolone hydrochloride 1·HC1 was achieved starting from di‐tert‐butyl hydrazodiformate (8). The route entails cyclization of 8 with 1,3‐dibromopropane under phase transfer conditions followed by deprotection of 1,2‐di‐tert‐butoxycarbonylpyrazolidine (9) to give pyrazolidine hydrochloride (2·HC1). Cyanoacetylation of the latter and ring closure of the resulting cyanoacetyl pyrazolidine (7) gave 1·HC1. This novel synthesis circumvents distillation of pyrazolidine (2) and flash chromatography to provide the hydrochloride of 1 in 35–46% overall yields compared to 6% yield for the patent procedure.
Preparation of 1H‐pyrazole‐5‐carboxamides from dilithiated C(α), N‐phenylhydrazones and lithiated ethyl oxanilates or lithiated ethyl oxamate
Authors: Downs Jennifer R. , Pastine Stefan J. , Schady Deborah A. , Greer Heather A. , Kelley Wayne , Embree Mildred C. , Townsend Jessica D. , Beam Charles F. 
Published: March 2009

AbstractDilithiated C(α), N‐phenylhydrazones were prepared in excess lithium diisopropylamide and condensed with either ethyl oxanilate, ethyl 4′‐chlorooxanilate, or ethyl oxamate to give intermediates that were quenched and acid cyclized to substituted lH‐pyrazole‐5‐carboxamides.
The syntheses of nitrogen‐oxygen donor macrocycles containing pyridine ring
Authors: Zhao Bin , Wang Feng Qin , Tian Lai Jin 
Published: March 2009

AbstractFive new nitrogen‐oxygen mixed donor macrocycles have been prepared by condensation of 2,6‐bis [(2‐formylphenyl)oxymethyl]pyridine with different diamino compounds in hot methanol, followed by a one‐pot reduction of the intermediate bis‐Schiff base. All the macrocycles were identified by elemental analysis, and ir, uv, and nmr spectroscopy.