Polycyclic N‐Heterocyclic Compounds. Part 86: Synthesis and Evaluation of Antiplatelet Aggregation Activity of 2,4‐Disubstituted 9‐Chloro‐5,6‐dihydropyrimido[5,4‐d]benzazepine and Related Compounds

Libraries of tricyclic 2‐substituted 4‐alkylamino‐9‐chloro‐5,6‐dihydropyrimido[5,4‐d]benzazepines and tetracyclic 12‐substituted 8‐chloro‐1,2,5,6‐tetrahydro‐4H‐imidazo[1′,2′:1,6]pyrimido[5,4‐d]benzazepines were synthesized as part of our research to develop new effective antiplatelet drugs. Several alkyl and aryl groups were used as substituents at the 2‐position. Evaluation of the effects of the newly synthesized compounds on collagen‐induced platelet aggregation revealed several promising antiplatelet candidates with potencies superior to aspirin.     

Ag Loaded on SiO2 as an Efficient and Recyclable Heterogeneous Catalyst for the Synthesis of Chloro‐8‐substituted‐9H‐purines

Ag support on silica has been used as an effective heterogeneous catalyst for the facile synthesis of chloro‐8‐substituted‐9H‐purine derivatives via the one‐pot reaction of 6‐chloro‐pyrimidines and substituted acids. The title compounds were formed as excellent yields with short reaction time under eco‐friendly conditions. The prepared catalyst (Ag/SiO₂) can be reused for a number of times with insignificant loss in its activity. This route has the advantage of being a cost‐effective, readily available, easy workup procedure.     

Influence du silicium et du germanium sur l'ene-reaction-comportement inattendu des allenylsilanes

The determining role of silicon and germanium for ene syntheses was confirmed in the reactions between 1-sila and 1-germacyclopent-3 enes or allenylsilanes and PhSO₂NSO, a highly reactive new enophile. In the case of the cyclic enes the reaction led to new α,β-unsaturated β-functional cyclic derivatives which can be easily reduced into the corresponding thiols. With allenylsilanes, the adducts resulting from the ene-reaction with PhSO₂NSO or 4-phenyl 1,2,4-triazoline 3,5-dione have an acetylene structure whereas the substituted allenes usually give conjugated diene derivatives.     

Structural Features of Certain p‐substituted Phenyl 2‐nitrovinyl Sulfones

The structure of p‐substituted phenyl 2‐nitrovinyl sulfones was studied through different spectral methods. It has been found that the nucleophilic substitution reactions of sodium phenylsulfinates with 1‐chloro‐2‐nitroethene occur stereospecifically. The formation of E‐isomers of this type of substituted phenyl vinyl sulfones was confirmed by FTIR and NMR spectroscopy. It was suggested that the E‐isomers formation was determined by the more stable conformation of the carbanionic intermediate as a result of intramolecular rotation around single Cα‐Cβ bond. This appears to be the product‐determining pathway during the interaction of sodium phenyl sulfinates with the highly activated substrate 1‐chloro‐2‐nitroethene.     

Survey Reactivity of Some Substituted Quinazolinones with Pentafluoro(chloro)pyridine

A new series of 4‐hetroaryl substituted quinazolines were designed and synthesized by the reaction of pentafluoro(chloro)pyridine and 2‐substituted quinazolinone. The aromatic nucleophilic substitution of pentafluoro(chloro)pyridine with quinazolinone occurs at the 4‐position of pyridine ring by the oxygen site (O‐centered nucleophile) of quinazolinone. The structures of all the compounds were confirmed by IR, ¹H NMR, ¹⁹F NMR, and ¹³C NMR spectroscopy as well as elemental analysis.     

Cyclization of Cyanoethylated Ketones as a Route to 6‐Substituted Indole Derivatives

δ‐Cyanoketones are quickly cyclized with KOtBu to 3‐aminocyclohex‐2‐enone derivatives, which in turn will give substituted indoles when treated with oxalyl chloride. Thus, 3‐amino‐6,6‐dimethylcyclohex‐2‐enone gave 3‐chloro‐6,6‐dimethyl‐2,5,6,7‐tetrahydroindole‐2,5‐dione, whose structure was corroborated by X‐ray crystallography, whereas the corresponding molecule without the blocking gem‐dimethyl groups, 3‐aminocyclohex‐2‐enone, gave via hydrogen shifts 6‐chloro‐3‐hydroxyoxindole.     

Synthesis of Substituted Pyrazolo[3,4‐b]Pyridines

The synthesis of different substituted pyrazolo[3,4‐b]pyridines by the reaction of 3‐amino‐5‐chloro‐1‐phenylpyrazole‐4‐carboxaldehyde 1 as starting material with some active methylene reagents has been reported.     

Efficient Synthesis of 3‐Substituted Coumarins

Abstract

The Mukaiyama's esterification protocol, using 2‐chloro‐1‐methylpyridinium iodide‐triethylamine reagent, has been successfully exploited to provide rapid access to a variety of 3‐substituted coumarins in satisfactory yields.     

Synthesis and characterization of stable betainic pyrimidinaminides

Depending on electronically or kinetically stabilizing effects determined by the substitution pattern or the reaction conditions, 6‐amino substituted (5‐chloropyrimidine‐2,4‐diyl)bis(hetarenium) salts or 5‐chloro‐2,6‐bis‐(pyridinio)‐pyrimidin‐4‐aminides are formed on nucleophilic substitution of 4‐(dimethylamino)pyridine, 4‐(pyrrolidin‐1‐yl)pyridine, or 1‐methylimidazole on 4‐amino substituted 2,5,6‐trichloropyrimidines.     

Synthesis and biological properties of 4‐substituted quinolin‐2(1H)‐one analogues

A variety of 4‐substituted quinolin‐2(1H)‐ones were prepared and evaluated for N‐methyl‐D‐aspar‐tate (NMDA) receptor binding site activity and their abilities to inhibit neurotoxicity. The 4‐(2‐car‐bethoxyethanamino)‐7‐chloro‐3‐nitroquinolin‐2(1H)‐one ( 9b ) exhibited favorable NMDA receptor binding site activity and 7‐chloro‐4‐(benzylamino)‐3‐nitroquinolin‐2(1H)‐one ( 9c ) showed the most potent neurotoxicity among them. The synthetic strategies involve the use of well known keto ester condensation and reductive ring cyclization of intermediates ( 2a‐d ) to afford 4‐substituted quinolin‐2(1H)‐ones.     

Synthesis and Transformations of 5‐Chloro‐2,2′‐Dipyrrins and Their Boron Complexes, 8‐Chloro‐BODIPYs

Symmetric dipyrrylketones 1 a , b were synthesized in two steps from the corresponding α‐free pyrroles, by reaction with thiophosgene followed by oxidative hydrolysis under basic conditions. The dipyrrylketones produced the corresponding 5‐chloro‐dipyrrinium salts or 5‐ethoxy‐dipyrrins on reaction with phosgene or Meerwein’s salt, respectively. Boron complexation of the dipyrrins afforded the corresponding 8‐functionalized BODIPYs (borondipyrromethenes) in high yields. The 5‐chloro‐dipyrrinium salts reacted with methoxide or ethoxide ions to produce monopyrrole esters, presumably via a 5,5‐dialkoxy‐dipyrromethane intermediate. In contrast, 8‐chloro‐BODIPYs underwent a variety of nucleophilic substitutions of the chloro group in the presence of alkoxide ions, Grignard reagents, and thiols. In the presence of excess alkoxide or Grignard reagent, at room temperature or above, substitution at the boron center also occurred. The 8‐chloro‐BODIPY was a particularly useful reagent for the preparation of 8‐aryl‐, 8‐alkyl‐, and 8‐vinyl‐substituted BODIPYs in very high yields, using Pd⁰‐catalyzed Stille cross‐coupling reactions. The X‐ray structures of eleven BODIPYs and two pyrroles are presented, and the spectroscopic properties of the synthesized BODIPYs are discussed.     

Facile Synthesis of 2‐Substituted 4‐Azaindoles

A novel and efficient strategy for the synthesis of 2‐substituted 4‐azaindoles from 2‐chloro‐3‐nitropyridine through Pd‐catalyzed Sonogashira cross‐coupling, followed by reduction and heteroannulation on t‐BuOK, is reported.     

Synthesis and spectral properties of 2‐[(o‐ and p‐substituted)aminophenyl] ‐3H‐5‐[(o‐ and p‐substituted)phenyl]‐7‐chloro‐1,4‐benzodiazepines

A series of twelve new 2‐[(o‐ and p‐substituted)aminophenyl]‐3H‐5‐[(o‐ and p‐substituted)phenyl]‐7‐chloro‐1,4‐benzodiazepines, which have possible pharmacological properties has been obtained. The synthesis was carried out following six steps. The structure of all products was corroborated by ir, ¹H nmr, ¹³C nmr and ms. In addition for the compound 2‐(o‐chloroaminophenyl)‐3H‐5‐(o‐fluorophenyl)‐7‐chloro‐1,4‐benzodiazepine 7, its structure was confirmed by X‐ray diffraction.     

A New Method for the Preparation of Intermediates for 2,6‐Substituted Anthrapyridazones

A new method for the preparation of 2‐substituted 6‐chloro‐2,7‐dihydro‐3H‐dibenzo[de ,h ]cynnoline‐3,7‐diones has been developed. The compounds have been obtained in an original three‐step procedure comprising the oxidation of 1‐methyl‐9,10‐anthraquinones with periodate or permanganate/brominating reagent systems, cyclization to 6‐chloro‐2,7‐dihydro‐3H‐dibenzo[de ,h ]cynnoline‐3,7‐dione, and selective alkylation thereof. The selected processes were applied in the efficient scale‐up of specific 2,6‐substituted 2,7‐dihydro‐3H‐dibenz[de ,h ]cinnolin‐3,7‐dione derivatives, currently being investigated pre‐clinically as anticancer agents.     

Synthesis,Chemical Characterization,DNA Interaction and Antioxidant,Studies of New Nitrosubstituted Thioureas and Their Copper Complexes

In the present work new nitro substituted thioureas, and their copper complexes have been synthesized and characterized by FTIR and multinuclear NMR techniques. Some of the compounds namely 1‐benzoyl‐3‐(4‐chloro‐3‐nitrophenyl) thiourea (A‐1), 1‐benzoyl‐3‐(4‐chloro‐3‐nitrophenyl) thiourea (A‐2) and 1‐benzoyl‐3‐(2‐methoxy‐4‐nitrophenyl) thiourea (A‐2) have also been characterized by single crystal XRD. All the synthesized compounds have been screened for DNA binding potencies (using cyclic voltametry, UV‐vis spectroscopy) and free radical scavanging activities.     

Efficient synthesis and spectral determination of 11‐[(o‐ m‐ and p‐substituted)‐phenyl]‐8‐chloro‐3,3‐dimethyl‐2,3,4,5,10,11‐hexahydro‐1H‐dibenzo[b,e][1,4]diazepin‐1‐ones

A new synthesis to obtain eleven novel derivatives of 11‐[(o‐ m‐ and p‐substituted)‐phenyl]‐8‐chloro‐3,3‐dimethyl‐2,3,4,5,10,11‐hexahydro‐1H‐dibenzo[b,e][1,4]diazepin‐1‐ones with possible pharmacological activity in the central nervous system in two efficient steps has been developed. The final products were obtained by condensation and cyclization between 3‐[4‐chloro‐1,2‐phenylenediamine]‐5,5‐dimethyl‐2‐cyclohexenone with (o‐ m‐ and p‐substituted)benzaldehyde. The structure of all products was corroborated by ir, ¹H‐nmr, ¹³C‐nmr and high resolution in ms.     

A Novel One‐Pot Synthesis of Fully Substituted Thiophen‐2(3H)‐ones Using N,N‐Disubstituted Thioamides

A new one‐step synthesis of highly substituted thiophen‐2(3H)‐one derivatives was developed. 2‐Aryl‐1‐(morpholin‐4‐yl)ethanethiones were reacted with 2‐chloro‐2‐phenylacetyl chloride in DMF in the presence of a base to give the title compounds in moderate‐to‐good yields.     

Carbolithiation of Chloro‐Substituted Alkynes: A New Access to Vinyl Carbenoids

The intramolecular carbolithiation of a series of chloro‐substituted alkynes leads to exocyclic alkylidene carbenoids of which both nucleophilic and electrophilic characters can be drove. A sole stereoselective 5‐exo‐dig addition takes place, probably because of a strong and persisting Li–Cl interaction arising before the transition state.     

A Green Mechanochemical Synthesis of New 3,5‐Dimethyl‐4‐(arylsulfanyl)pyrazoles

A small series of new 3,5‐dimethyl‐4‐(arylsulfanyl)pyrazoles have been synthesized in good to excellent yields by a grinding‐induced, sequential one‐pot three‐component reaction, of an equimolar mixture of 3‐chloro‐2,4‐pentanedione, differently substituted thiophenols, and hydrazine hydrate in the presence of piperidine under solvent‐free conditions.     

Solvent and substituent effects on the reaction of 2‐ and 4‐chloro‐3,5‐dinitrobenzotrifluorides with substituted anilines

The solvent effect on a nucleophilic substitution reaction of 2‐ and 4‐chloro‐3,5‐dinitrobenzotrifluoride with substituted anilines was studied in methanol, acetonitrile, and toluene at 25°C. This reaction is of second order, except 2‐chloro‐3,5‐dinitrobenzotrifluoride in toluene shows third order. The k_A values are found to be dependent on the substituent in aniline and give good Hammett correlations. The obtained ρ values are ?4.07 and ?4.62, for the reaction of anilines with 2‐chloro‐3,5‐dinitrobenzotrifluoride in methanol and acetonitrile, respectively. The ρ values for the reaction of the anilines with 4‐chloro‐3,5‐dinitrobenzotrifluoride are ?3.38, ?4.11, and ?4.34 in methanol, acetonitrile, and toluene, respectively. The reaction of the former compound with anilines in toluene shows a second order in aniline. The dependence of the reaction on the external base such as DABCO suggests a proton transfer controlling step. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 777–786, 2009