Synthesis and reactions of 3‐amino‐2‐methyl‐3H‐[1,2,4]triazolo[5,1‐b]‐quinazolin‐9‐one and 2‐hydrazino‐3‐phenylamino‐3H‐quinazolin‐4‐one

The reaction of 3‐N‐(2‐mercapto‐4‐oxo‐4H‐quinazolin‐3‐yl)acetamide ( 1 ) with hydrazine hydrate yielded 3‐amino‐2‐methyl‐3H‐[1,2,4]triazolo[5,1‐b]quinazolin‐9‐one ( 2 ). The reaction of 2 with o‐chlorobenzaldehyde and 2‐hydroxy‐naphthaldehyde gave the corresponding 3‐arylidene amino derivatives 3 and 4 , respectively. Condensation of 2 with 1‐nitroso‐2‐naphthol afforded the corresponding 3‐(2‐hydroxy‐naphthalen‐1‐yl‐diazenyl)‐2‐methyl‐3H‐[1,2,4]triazolo[5,1‐b]quinazolin‐9‐one ( 5 ), which on subsequent reduction by SnCl₂ and HCl gave the hydrazino derivative 6. Reaction of 2 with phenyl isothiocyanate in refluxing ethanol yielded thiourea derivative 7. Ring closure of 7 subsequently cyclized on refluxing with phencyl bromide, oxalyl dichloride and chloroacetic acid afforded the corresponding thiazolidine derivatives 8, 9 and 10 , respectively. Reaction of 2‐mercapto‐3‐phenylamino‐3H‐quinazolin‐4‐one ( 11 ) with hydrazine hydrate afforded 2‐hydrazino‐3‐phenylamino‐3H‐quinazolin‐4‐one ( 12 ). The reactivity 12 towards carbon disulphide, acetyl acetone and ethyl acetoacetate gave 13, 14 and 15 , respectively. Condensation of 12 with isatin afforded 2‐[N‐(2‐oxo‐1,2‐dihydroindol‐3‐ylidene)hydrazino]‐3‐phenylamino‐3H‐quinazolin‐4‐one ( 16 ). 2‐(4‐Oxo‐3‐phenylamino‐3,4‐dihydroquinazolin‐2‐ylamino)isoindole‐1,3‐dione ( 17 ) was synthesized by the reaction of 12 with phthalic anhydride. All isolated products were confirmed by their ir, ¹H nmr, ¹³C nmr and mass spectra.     

Stereoselective Synthesis of [5‐[4,4,4,4′,4′,4′‐Hexafluoro‐N‐(2‐hydroxyethoxy)‐D‐valine]]‐ and [5‐[4,4,4,4′,4′,4′‐Hexafluoro‐N‐(2‐hydroxyethoxy)‐L‐valine]cyclosporin A

Addition of various amines to the 3,3‐bis(trifluoromethyl)acrylamides 10a and 10b gave the tripeptides 11a – 11f , mostly as mixtures of epimers (Scheme 3). The crystalline tripeptide 11f ₂ was found to be the N‐terminal (2‐hydroxyethoxy)‐substituted (R,S,S)‐ester HOCH₂CH₂O‐D ‐Val(F₆)‐MeLeu‐Ala‐O^tBu by X‐ray crystallography. The C‐terminal‐protected tripeptide 11f ₂ was condensed with the N‐terminus octapeptide 2b to the depsipeptide 12a which was thermally rearranged to the undecapeptide 13a (Scheme 4). The condensation of the epimeric tripeptide 11f ₁ with the octapeptide 2b gave the undecapeptide 13b directly. The undecapeptides 13a and 13b were fully deprotected and cyclized to the [5‐[4,4,4,4′,4′,4′‐hexafluoro‐N‐(2‐hydroxyethoxy)‐D ‐valine]]‐ and [5‐[4,4,4,4′,4′,4′‐hexafluoro‐N‐(2‐hydroxyethoxy)‐L ‐valine]]cyclosporins 14a and 14b , respectively (Scheme 5). Rate differences observed for the thermal rearrangements of 12a to 13a and of 12b to 13b are discussed.     

Fused quinoline heterocycles VI: Synthesis of 5H‐1‐thia‐3,5,6‐triazaaceanthrylenes and 5H‐1‐thia‐3,4,5,6‐tetraazaaceanthrylenes

Ethyl 3‐amino‐4‐chlorothieno[3,2‐c]quinoline‐2‐carboxylate ( 4 ) is a versatile synthon, prepared by reacting an equimolar amount of 2,4‐dichloroquinoline‐3‐carbonitrile ( 1 ) with ethyl mercaptoacetate ( 2 ). Ethyl 5‐alkyl‐5H‐1‐thia‐3,5,6‐triazaaceanfhrylene‐2‐carboxylates 9a‐c , novel perianellated tetracyclic heteroaro‐matics, were prepared by refluxing 4 with excess of primary amines 7a‐c to yield the corresponding amino‐thieno[3,2‐c]quinolines 8a‐c . Subsequent reaction with an excess of triethyl orthoformate (TEO) furnished 9a‐c . Reaction of 4 with TEO in Ac₂O at reflux, gave the simple acetylated compounds, thieno[3,2‐c]‐quinolines 12 and 13 . Refluxing 4 with benzylamine ( 7d ) gave 10 , and subsequent treatment with TEO gave the tetracyclic compound 11 . Refluxing 13 with an excess of alkylamines 7a‐d gave the fhieno[3,2‐c]quino‐lines 15 . Refluxing the aminothienoquinolines 8b with an excess of triethyl orthoacetate gave thieno[3,2‐c]quinoline 17 , while heating with Ac₂O gave 18 and 19 , with small amounts of 16 . Reaction of 8a,b with ethyl chloroformate and phenylisothiocyanate generated the new 1‐thia‐3,5,6‐triazaaceanthrylenes 20a,b and 21a,b , respectively. Diazotization of 8a‐c afforded the novel tetracyclic ethyl 5‐alkyl‐5H‐1‐fhia‐3,4,5,6‐tetraazaaceanthrylene‐2‐carboxylates 22a‐c in good yields.     

Abnormal reactions of 2‐methoxy‐4,9‐dimethyl‐1‐nitroacridine with selenous acid and selenium(IV) oxide. Synthesis of 1H‐selenopheno[2,3,4‐k,l]acridine‐1‐one: A new seleno‐containing ring system

Unusual course of the reaction was revealed on the oxidation of functionally substituted acridine containing the activated methyl groups by well‐known oxidants, such as selenous acid and selenium(IV) oxide. Treatment of 2‐methoxy‐4,9‐dimethyl‐1‐nitroacridine ( 5 ) with an excess of H₂SeO₃ in boiling ethanol gave a mixture of the normal reaction products, 2‐methoxy‐4‐methyl‐1‐nitro‐9‐formylacridine ( 11 ) (isolated yield 29%) and 2‐methoxy‐4‐methyl‐1‐nitroacridine‐9‐carboxylic acid ( 12 ) (36%), together with an abnormal product, 3‐methoxy‐5‐methyl‐1H‐selenopheno[2,3,4‐k,l]acridine‐1‐one ( 13 ) (21%), which is the first example of a new seleno‐containing ring system. With the use of SeO₂ the yield of selenolactone 13 was much lower. J. Heterocyclic Chem., 2011.     

6‐(Diazomethyl)‐1,3‐bis(methoxymethyl)uracil,Synthesis and Transformation into Annulated Pyrimidinediones

6‐(Diazomethyl)‐1,3‐bis(methoxymethyl)uracil ( 5 ) was prepared from the known aldehyde 3 by hydrazone formation and oxidation. Thermolysis of 5 and deprotection gave the pyrazolo[4,3‐d]pyrimidine‐5,7‐diones 7a and 7b . Rh₂(OAc)₄ catalyzed the transformation of 5 into to a 2 : 1 (Z)/(E) mixture of 1,2‐diuracilylethenes 9 (67%). Heating (Z)‐ 9 in 12n HCl at 95° led to electrocyclisation, oxidation, and deprotection to afford 73% of the pyrimido[5,4‐f]quinazolinetetraone 12 . The Rh₂(OAc)₄‐catalyzed reaction of 5 with 3,4‐dihydro‐2H‐pyran and 2,3‐dihydrofuran gave endo/exo‐mixtures of the 2‐oxabicyclo[4.1.0]heptane 13 (78%) and the 2‐oxabicyclo[3.1.0]hexane 15 (86%), Their treatment with AlCl₃ or Me₂AlCl promoted a vinylcyclopropane–cyclopentene rearrangement, leading to the pyrano‐ and furanocyclopenta[1,2‐d]pyrimidinediones 14 (88%) and 16 (51%), respectively. Similarly, the addition product of 5 to 2‐methoxypropene was transformed into the 5‐methylcyclopenta‐pyrimidinedione 18 (55%). The Rh₂(OAc)₄‐catalyzed reaction of 5 with thiophene gave the exo‐configured 2‐thiabicyclo[3.1.0]hexane 19 (69%). The analoguous reaction with furan led to 8‐oxabicyclo[3.2.1]oct‐2‐ene 20 (73%), and the reaction with (E)‐2‐styrylfuran yielded a diastereoisomeric mixture of hepta‐1,4,6‐trien‐3‐ones 21 (75%) that was transformed into the (1E,4E,6E)‐configured hepta‐1,4,6‐trien‐3‐one 21 (60%) at ambient temperature.     

Diels‐alder reactions of 2‐(2‐nitroethenyl)‐1H‐pyrroles and their oxygen and sulfur analogs with quinones

Diels‐Alder reaction of 2‐(E‐2‐nitroethenyl)‐1H‐pyrrole ( 2a ) with 1,4‐benzoquinone gave the desired benzo[e]indole‐6, 9(3H)‐dione ( 4a ) in 10% yield versus a 26% yield (lit. 86% [5]) of the known N‐methyl compound ( 4b ) from the N‐(or 1)‐methyl compound ( 2b ). Protection of the nitrogen of 2a with a phenylsul‐fonyl group ( 2c ) gave a 9% yield of the corresponding N‐(or 3)‐phenylsulfonyl compound ( 4c ). The reaction of 2b with 1,4‐naphthoquinone gave in 6% yield (lit. 64% [5]) the known 3‐methylnaphtho[2,3‐e]‐indole‐6, 9(3H)‐dione ( 6 ). The reaction of 2‐(E‐2‐nitroethenyl)furan ( 8a ) gave a small yield of the desired naphtho[2,1‐b]furan‐6, 9‐dione ( 9a ), recognized by comparing its NMR spectrum with that of 4b. The corresponding reaction of 2‐(E‐2‐nitroethenyl)thiophene ( 8b ) gave a 4% yield of naphtho[2,1‐ b ]thiophene‐6,9‐dione ( 9b ), previously prepared in 24% yield [12] in a three‐step procedure involving 2‐ethenylthiophene. Introducing an electron‐releasing 2‐methyl substituent into 8a and 8b gave 12a and 12b , which, upon reaction with 1,4‐benzoquinone, gave 2‐methylnaphtho[2,1‐b]furan‐6, 9‐dione ( 13a ) and its sulfur analog ( 13b ) in yields of 4 and 8%, respectively.     

Synthesis of 1,3‐Selenazol‐2(3H)‐imines

The reaction of N,N′‐diarylselenoureas 16 with phenacyl bromide in EtOH under reflux, followed by treatment with NH₃, gave N,3‐diaryl‐4‐phenyl‐1,3‐selenazol‐2(3H)‐imines 13 in high yields (Scheme 2). A reaction mechanism via formation of the corresponding Se‐(benzoylmethyl)isoselenoureas 18 and subsequent cyclocondensation is proposed (Scheme 3). The N,N′‐diarylselenoureas 16 were conveniently prepared by the reaction of aryl isoselenocyanates 15 with 4‐substituted anilines. The structures of 13a and 13c were established by X‐ray crystallography.     

Reactions of Stable α‐Chlorosulfanyl Chlorides with CS‐Functionalized Compounds

The smooth reaction of 3‐chloro‐3‐(chlorosulfanyl)‐2,2,4,4‐tetramethylcyclobutanone ( 3 ) with 3,4,5‐trisubstituted 2,3‐dihydro‐1H‐imidazole‐2‐thiones 8 and 2‐thiouracil ( 10 ) in CH₂Cl₂/Et₃N at room temperature yielded the corresponding disulfanes 9 and 11 (Scheme 2), respectively, via a nucleophilic substitution of Cl^? of the sulfanyl chloride by the S‐atom of the heterocyclic thione. The analogous reaction of 3‐cyclohexyl‐2,3‐dihydro‐4,5‐diphenyl‐1H‐imidazole‐2‐thione ( 8b ) and 10 with the chlorodisulfanyl derivative 16 led to the corresponding trisulfanes 17 and 18 (Scheme 4), respectively. On the other hand, the reaction of 3 and 4,4‐dimethyl‐2‐phenyl‐1,3‐thiazole‐5(4H)‐thione ( 12 ) in CH₂Cl₂ gave only 4,4‐dimethyl‐2‐phenyl‐1,3‐thiazol‐5(4H)‐one ( 13 ) and the trithioorthoester derivative 14 , a bis‐disulfane, in low yield (Scheme 3). At ?78°, only bis(1‐chloro‐2,2,4,4‐tetramethyl‐3‐oxocyclobutyl)polysulfanes 15 were formed. Even at ?78°, a 1 : 2 mixture of 12 and 16 in CH₂Cl₂ reacted to give 13 and the symmetrical pentasulfane 19 in good yield (Scheme 5). The structures of 11, 14, 17 , and 18 have been established by X‐ray crystallography.     

A Novel Synthetic Approach to (±)‐Desoxynoreseroline

(±)‐Desoxynoreseroline ( 3 ), the basic ring structure of the pharmacologically active alkaloid physostigmine ( 1 ), was synthesized starting from 3‐allyl‐1,3‐dimethyloxindole ( 9 ). The latter was prepared from the corresponding 2H‐azirin‐3‐amine 6 by a BF₃‐catalyzed ring enlargement via an amidinium intermediate 7 (Scheme 1). An alternative synthesis of 9 was also carried out by the reaction of N‐methylaniline with 2‐bromopropanoyl bromide ( 12 ), followed by intramolecular Friedel–Crafts alkylation of the formed anilide 13 to give Julian's oxindole 11 . Further alkylation of 11 with allyl bromide in the presence of LDA gave 9 in an excellent yield (Scheme 3). Ozonolysis of 9 , followed by mild reduction with (EtO)₃P, gave the aldehyde 14 , whose structure was chemically established by the transformation to the corresponding acetal 15 (Scheme 4). Condensation of 14 with hydroxylamine and hydrazine derivatives, respectively, gave the corresponding imine derivatives 16a – 16d as a mixture of syn‐ and anti‐isomers. Reduction of this mixture with LiAlH₄ proceeded by loss of ROH or RNH₂ to give racemic 3 (Scheme 5).     

Functionalized 2‐Hydrazinobenzothiazole with Isatin and Some Carbohydrates under Conventional and Ultrasound Methods and Their Biological Activities

Several chemical reactions were carried out on 3‐(benzothiazol‐2‐yl‐hydrazono)‐1,3‐dihydro‐indol‐2‐one ( 2 ). 3‐(Benzothiazol‐2‐yl‐hydrazono)‐1‐alkyl‐1,3‐dihydro‐indol‐2‐one 3a , 3b , 3c have been achieved. Reaction of compound 2 with ethyl bromoacetate in the presence of K₂CO₃ resulted the uncyclized product 4 . Reaction of compound 2 with benzoyl chloride afforded dibenzoyl derivative 5 . Compound 2 was smoothly acetylated by acetic anhydride in pyridine to give diacetyl derivative 6b . Moreover, when compound 4 reacted with methyl hydrazine, it yielded dihydrazide derivative 7 , whereas the hydrazinolysis of this compound with hydrazine hydrate gave the monohydrazide derivative 8 . {N‐(Benzothiazol‐2‐yl‐N′‐(3‐oxo‐3,4‐dihydro‐2H‐1,2,4‐triaza‐fluoren‐9‐ylidene)hydrazino]‐acetic acid ethyl ester ( 9 ) was prepared by ring closure of compound 8 by the action of glacial acetic acid. In addition, the reaction of 2‐hydrazinobenzothiazole ( 1 ) with d ‐glucose and d ‐arabinose in the presence of acetic acid yielded the hydrazones 10a , 10b , respectively. Acetylation of compound 10b gave compound 11b . On the other hand, compound 13 was obtained by the reaction of compound 1 with gama‐d ‐galactolactone ( 12 ). Acetylation of compound 13 with acetic anhydride in pyridin gave the corresponding N¹‐acetyl‐N²‐(benzothiazolyl)‐2‐yl)‐2,3,4,5,6‐penta‐O‐acetyl‐d ‐galacto‐hydrazide ( 14 ). Better yields and shorter reaction times were achieved using ultrasound irradiation. The structural investigation of the new compounds is based on chemical and spectroscopic evidence. Some selected derivatives were studied for their antimicrobial and antiviral activities.     

Lipase‐catalyzed polymerization of fluorinated lactones and fluorinated hydroxycarboxylic acids

Lipase‐catalyzed ring‐opening polymerization of 10‐fluorodecan‐9‐olide (1a), 11‐fluoroundecan‐10‐olide (1b), 12‐fluorododecan‐11‐olide (1c) and 14‐fluorotetradecan‐13‐olide (1d) gave optically active products with M_w of 3.000 to 8.000, while 10‐fluoroundecan‐11‐olide (3a) gave an optically inactive polymer with M_w = 11.000. On the other hand, Candida antarctica lipase‐catalyzed polymerization of 10‐ to 14‐membered ω‐fluoro‐(ω‐1)‐hydroxyalcanoic acids gave optically inactive oligomers with M_w of 3.000 to 11.000 in the presence of molecular sieves, while reactions without molecular sieves gave oligomers with lower molecular weight, but with small optical rotations. 9‐Fluoro‐10‐hydroxydecanoic acid, on the other hand, gave an optically inactive polyester with M_w = 7400. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2004–2012, 2000     

Redox Reaction of the Pd0 Complex Bearing the Trost Ligand with meso‐Cycloalkene‐1,4‐biscarbonates Leading to a Diamidato PdII Complex and 1,3‐Cycloalkadienes: Enantioselective Desymmetrization Versus Catalyst Deactivation

The Pd⁰ complex 1 that bears the Trost ligand 2 undergoes a facile redox reaction with 1,4‐biscarbonates 5 b – d and rac‐ 22 under formation of the diamidato–Pd^II complex 7 and the corresponding 1,3‐cycloalkadienes 8 b – d . The redox deactivation of complex 1 was the dominating pathway in the reaction of 5 b – d with HCO₃^? at room temperature. However, at 0 °C the six‐membered biscarbonate 5 b , catalytic amounts of complex 1 , and HCO₃^? mainly reacted in an allylic alkylation, which led to a highly selective desymmetrization of the substrate and gave alcohol 6 b with ≥99 % ee in 66 % yield. An increase of the catalyst loading in the reaction of 5 b with 1 and HCO₃^? afforded the bicyclic carbonate 12 b (96 % ee, 92 %). Formation of carbonate 12 b involves two consecutive inter‐ and intramolecular substitution reactions of the π‐allyl–Pd^II complexes 16 b and 18 b , respectively, with O‐nucleophiles and presumably proceeds through the hydrogen carbonate 17 b as key intermediate. The intermediate formation of 17 b is also indicated by the conversion of alcohol rac‐ 6 b to carbonate 12 b upon treatment with HCO₃^? and 1 . The Pd⁰‐catalyzed desymmetrization of 5 b with formation of 12 b and its hydrolysis allow an efficient enantioselective synthesis of diol 13 b . The reaction of the seven‐membered biscarbonate 5 c with ent‐ 1 and HCO₃^? afforded carbonate ent‐ 12 c (99 % ee, 39 %). The Pd⁰ complex 1 is stable in solution and suffers no intramolecular redox reaction with formation of complex 7 and dihydrogen as recently claimed for the similar Pd⁰ complex 9 . Instead, complex 1 is rapidly oxidized by dioxygen to give the stable Pd^II complex 7 . Thus, formation of the Pd^II complex 10 from 9 was most likely due to an oxidation by dioxygen. Oxidative workup (air) of the reaction mixture stemming from the desymmetrization of 5 c catalyzed by 1 gave the Pd^II complex 7 in high yield besides carbonate 12 c .     

Synthesis and Reactions of a New Cyclobutanethione Derivative

The 3,3‐dichloro‐2,2,4,4‐tetramethylcyclobutanethione ( 4b ) was prepared from the parent diketone by successive reaction with PCl₅ and Lawesson reagent in pyridine. This new thioketone 4b was transformed into 1‐chlorocyclobutanesulfanyl chloride 5 and chloro 1‐chlorocyclobutyl disulfide 9 by treatment with PCl₅ and SCl₂, respectively, in chlorinated solvents (Schemes 1 and 2). These products reacted with S‐ and P‐nucleophiles by substitution of Cl⁻ at the S‐atom; e.g., the reaction with 4b yielded the di‐ and trisulfides 6b and 11 , respectively. Surprisingly, only pentasulfide 12 was formed in the reaction of 9 with thiobenzophenone (Scheme 3). In contrast to 5 and 9 , the corresponding chloro 1‐chlorocyclobutyl trisulfide 13 could not be detected, but reacted immediately with the starting thioketone 4b to give the tetrasulfide 14 (Scheme 4). Oxidation of 4b with 3‐chloroperbenzoic acid (mCPBA) yielded the corresponding thione oxides (= sulfine) 15 , which underwent 1,3‐dipolar cycloadditions with thioketones 3a and 4b (Scheme 5). Furthermore, 4b was shown to be a good dipolarophile in reactions with thiocarbonylium methanides (Scheme 6) and iminium ylides (= azomethine ylides; Scheme 7). In the case of phenyl azide, the reaction with 4b gave the symmetrical trithiolane 25 (Scheme 8).     

Amino acid derivatives,part 2: Synthesis,antiviral, and antitumor activity of simple protected amino acids functionalized at N‐terminus with naphthalene side chain

Coupling of various acylated amino acid derivatives with (naphthalen‐2‐lyloxy)acetic acid ( 3 ) in the presence of 1‐hydroxy‐benzoteriazole (HOBt) and DCC afforded the new amides 6–12 . Alternatively, the latter compounds were prepared from reaction of the corresponding hydrazide 5 , via the azide‐coupling method, with the acylated amino acid derivatives. Treatment of 6, 10–12 with N₂H₄ċH₂O afforded the hydrazides 13–16 , respectively, as key intermediates for the synthesis of peptide derivatives. Reaction of 12 , as a acceptor, with the glycosyl‐trichloroimidate 18 , as donors in the presence of TMSOTf gave the new glycoside 19 . The new compounds were evaluated for their anti‐HIV‐1, antibovine viral diarrhea virus (BVDV), and antitumor activity. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:148–222, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20082     

1,3-Dipolar cycloaddition of α-alkoxycarbonylnitrones with vinyl ethers and allyl alcohols in the presence of Eu(fod)3: selective activation of (Z)-isomers of the nitrones

Uncatalyzed cycloaddition of α-alkoxycarbonylnitrones 1 with vinyl ethers 7 gave mixtures of cis- and trans-cycloadducts 8, whereas Eu(fod)₃-catalyzed cycloaddition of 1 with 7 gave the trans-cycloadducts trans-8 in a highly stereoselective manner. NMR studies indicated that Eu(fod)₃ selectively activated (Z)-nitrones (Z)-1 in E,Z-equilibrium mixtures of nitrones 1. In contrast, the reaction of 1 with allyl alcohols 12 in the presence of Eu(fod)₃ resulted in sequential transesterification and intramolecular cycloaddition to give intramolecular cycloadducts 13.     

Studies with Alkylheterocycles: Novel Synthesis of Functionally Substituted Isoquinoline and Pyridopyridines Derivatives

Several isoquinolines were prepared via reacting pyridine 4 with cinnamonitriles 5a‐c or 5d‐f . Treating 4 with elemental sulphur yielded thienopyridine 9. 9 reacts with acrylonitrile to give isoquinoline 12. 12 was also prepared from 4 and methylenemalononitrile. Condensation of 4 with aromatic aldehydes gave the arylidine 13. 13 afforded the pyridine 14 and 15 on treating it with NH₄OH and AcOH/HCl, respectively.     

Three‐Component Self‐Assembly of a Series of Triply Interlocked Pd12 Coordination Prisms and Their Non‐Interlocked Pd6 Analogues

Template‐assisted formation of multicomponent Pd₆ coordination prisms and formation of their self‐templated triply interlocked Pd₁₂ analogues in the absence of an external template have been established in a single step through Pd? N/Pd? O coordination. Treatment of cis‐[Pd(en)(NO₃)₂] with K₃tma and linear pillar 4,4′‐bpy (en=ethylenediamine, H₃tma=benzene‐1,3,5‐tricarboxylic acid, 4,4′‐bpy=4,4′‐bipyridine) gave intercalated coordination cage [{Pd(en)}₆(bpy)₃(tma)₂]₂[NO₃]₁₂ ( 1 ) exclusively, whereas the same reaction in the presence of H₃tma as an aromatic guest gave a H₃tma‐encapsulating non‐interlocked discrete Pd₆ molecular prism [{Pd(en)}₆(bpy)₃(tma)₂(H₃tma)₂][NO₃]₆ ( 2 ). Though the same reaction using cis‐[Pd(NO₃)₂(pn)] (pn=propane‐1,2‐diamine) instead of cis‐[Pd(en)(NO₃)₂] gave triply interlocked coordination cage [{Pd(pn)}₆(bpy)₃(tma)₂]₂[NO₃]₁₂ ( 3 ) along with non‐interlocked Pd₆ analogue [{Pd(pn)}₆(bpy)₃(tma)₂](NO₃)₆ ( 3′ ), and the presence of H₃tma as a guest gave H₃tma‐encapsulating molecular prism [{Pd(pn)}₆(bpy)₃(tma)₂(H₃tma)₂][NO₃]₆ ( 4 ) exclusively. In solution, the amount of 3′ decreases as the temperature is decreased, and in the solid state 3 is the sole product. Notably, an analogous reaction using the relatively short pillar pz (pz=pyrazine) instead of 4,4′‐bpy gave triply interlocked coordination cage [{Pd(pn)}₆(pz)₃(tma)₂]₂[NO₃]₁₂ ( 5 ) as the single product. Interestingly, the same reaction using slightly more bulky cis‐[Pd(NO₃)₂(tmen)] (tmen=N,N,N′,N′‐tetramethylethylene diamine) instead of cis‐[Pd(NO₃)₂(pn)] gave non‐interlocked [{Pd(tmen)}₆(pz)₃(tma)₂][NO₃]₆ ( 6 ) exclusively. Complexes 1 , 3 , and 5 represent the first examples of template‐free triply interlocked molecular prisms obtained through multicomponent self‐assembly. Formation of the complexes was supported by IR and multinuclear NMR (¹H and ¹³C) spectroscopy. Formation of guest‐encapsulating complexes ( 2 and 4 ) was confirmed by 2D DOSY and ROESY NMR spectroscopic analyses, whereas for complexes 1 , 3 , 5 , and 6 single‐crystal X‐ray diffraction techniques unambiguously confirmed their formation. The gross geometries of H₃tma‐encapsulating complexes 2 and 4 were obtained by universal force field (UFF) simulations.     

Investigation on the condensation of α and β ketoaldehydes with hydroxyaromatic compounds

Mechanism of the condensation reactions of methylglyoxal, phenylglyoxal and benzoylacetaldehyde with phenolic compounds have been discussed. It was observed that the reaction mechanisms changed depending on the type of the phenolic and also dicarbonyl compounds. While, methylglyoxal gave the angular methyl derivative of naphthofuraranonaphthofuran with 2‐naphthol, phenylglyoxal and its p‐chloro and p‐methoxy derivatives formed benzo[b]naphtho[2,1‐f]oxepine‐13‐ones. However, resorcinol behaved different and gave 2‐phenyl‐3‐(2,4‐dihydroxy)‐6‐hydroxy‐benzo[b]furans with phenylglyoxal derivatives. 2‐Phenyl‐4‐(2‐hydroxynaphmyl)‐4H‐naphtho[b]pyran was produced from the reaction of benzoylacetaldehyde and 2‐naphthol, but the reaction product was 3,9‐dihydroxy‐6‐phenyl‐6,12‐methano‐12H‐dibenzo[1,3]dioxocin when the same carbonyl compound reacted with resorcinol.     

Synthesis of Functionalized 2‐Aminopyrroles by Lewis Acid Catalyzed Ring‐opening of 1,1,2,3‐Tetrasubstituted Cyclopropanes with Arylamines

Under the catalysis of Lewis acid Co(ClO₄)₂ the reaction of the sterically hindered 1,1,2,3‐tetrasubstituted cyclopropanes with arylamines in refluxing THF gave the functionalized 2‐aminopyrroles with sequential ring‐opening of cyclopropane, nucleophilic substitution, nucleophilic addition of cyano group and recyclization processes.     

Synthesis and Some Reactions of Quinoxalinecarboazides

Chlorination of ethyl(quinoxalin‐2(1H)one)‐3‐carboxylate 1 gave ethyl (2‐chloroquinoxaline)‐3‐carboxylate 2 ;thionation of 1 by P₂S₅ or 2 by thiourea yielded the same product 3 . Reaction of chloro compound 2 or thiocompound 3 with hydrazine hydrate gave pyrazolylquinoxaline 4 . The reaction of ester 1 with thiourea or hydrazine hydrate afforded pyrimido quinoxaline 5 or carbohydrazide 6 ; the reaction of 6 with carbon disulfide in basic medium followed by alkylation afforded oxadiazoloquinoxaline derivatives 7, 8a,b . Carboazide 9 was produced by reaction of 5 with nitrous acid. Compound 9 on heating in an inert solvent, with or without amines, in alcohols or hydrolysis in H₂O undergoes Curtius rearrangments to yield 10‐13 . Reaction of 13 with thiosemicarbazide gave triazoloquinoxaline 14 which on reaction with alkylhalides or hydrazine hydrate yielded 15a‐c while hydrolysis of 13 gave 3‐aminoquinoxalinone 16 which was used as an intermediate to produce 17‐20 .