bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis, structural, and biochemical study of a series of methyl 2,6‐diaryl‐1‐methyl‐4‐oxopiperidine‐3,5‐dicarboxylates and a series of methyl 2,4‐diaryl‐3,7‐dimethyl‐9‐oxo‐3,7‐diazabicyclo[3.3.1]nonane‐1,5‐dicarboxylates
Authors: Fernandez M. J. , Casares J. M. , Galvez E. , Gómez‐Sal P. , Torres R. , Ruiz P. 
Published: March 2009

AbstractA series of methyl‐2,6‐diaryl‐1‐methyl‐4‐oxopiperidine‐3,5‐dicarboxylates Ia‐c and 2,4‐diaryl‐3,7‐dimethyl‐1,5‐dimethoxycarbonyl‐9‐bispidinones IIa‐c have been synthesized and studied by ir, 1H and 13C nmr spectroscopy and the crystal structure of methyl 2,4‐diphenyl‐3,7‐dimethyl‐9‐oxo‐3,7‐diazabicyclo[3,3.1]nonane‐1,5‐dicarboxylate (IIa) has been determined by X‐ray diffraction. The enolic form of compound Ia (I'a) was also studied.
Assignments of the 1H and 13C NMR spectra of pseudo‐symmetric heterocyles using the HMQC‐TOCSY experiment to differentiate overlapping spin systems
Authors: Castle Lyle W. , Johnston Milton D. , Camoutsis Charalampos L. , Castle Raymond N. 
Published: March 2009

AbstractThe 1H nmr spectra of phenanthro[9′,10′:4,5]thieno[2,3‐c]quinoline, benzo[f]phenanthro‐[9′,10′:4,5]thieno[2,3‐c]quinoline and benzo[h]phenanthro[9′,10′:4,5]thieno[2,3‐c]quinoline are highly congested. For each compound, all protons abide in an aromatic environment complicated by pseudo‐symmetric regions which result in multiple overlap of the different spin systems these molecules contain. We illustrate here the utility of the HMQC‐TOCSY experiment to identify spin systems when the proton spectrum is highly congested. To complete the assignment of the 1H and 13C nmr spectra of each compound the HMBC experiment is used to assign the quaternary carbons.
Synthesis of N‐substituted α‐aminoacids from 4‐hydroxycoumarin
Authors: Hamdi Maǎmar , Sakellariou Reine , Spéziale Vincent 
Published: March 2009

AbstractA new series, the N‐(methylene‐4‐oxocoumarinyl)aminoacids were synthesized by condensation of 4‐hydroxycoumarin with α‐aminoacids in the presence of excess ethyl orthoformate.
The chemistry of 2H‐3,1‐benzoxazine‐2,4(1H)‐dione (isatoic anhydride). 22 . An efficient synthesis of leiokinine B
Authors: Coppola Gary M. 
Published: March 2009

AbstractThe alkaloid leiokinine B has been synthesized in one step from the reaction of N‐methylisatoic anhydride and the enolate derived from 3‐ethyl‐2‐pentanone.
On the formation of homo‐aza‐steroids and derivatives by beckmann rearrangement. Antitumor activity of stereoisomers homo‐aza‐steroidal esters
Authors: Catsoulacos P. , Catsoulacos D. 
Published: March 2009

AbstractThe Beckmann rearrangement of steroidal oximes is reported. Different methods of esterification of homo‐aza‐steroids with carboxylic derivatives of N,N‐bis(2‐chloroethyl)aniline are reported.The lipophilic nature of the steroidal hormones is the reason for searching compounds containing as the biological platform the steroid molecule and as the active moiety the alkylating agent, such as nitrogen mustards linked to the steroid with a stable bond or with an easily cleaved ester or ether molecule and different other active species, hopefully to transport and deliver the alkylating agent to the specific target tissue. The concept to design hybrid compounds containing as the biological platform steroidal lactams and as the alkylating congener carboxylic derivatives of N,N‐bis(2‐chloroethyl)aniline might form compounds with synergistic activity.The findings suggest that the conformation of the alkylating agent influences the anticancer activity, while the amide group of the lactam molecule is important for activity in L1210 leukemia.These hybrid compounds with a modified steroid as the biological platform furnish derivatives with advantages compared to the unmodified steroids with alkylating agents.Different methods of esterification of homo‐aza‐steroids with carboxylic derivatives of N,N‐bis(2‐chloro‐ethyl)aniline are reported.
Ring‐cleavage of isoxazoles with heterocyclic amines. Synthesis of fused pyrimidines
Authors: Bossio Ricardo , Marcaccini Stefano , Pepino Roberto , Paoli Paola 
Published: March 2009

AbstractThe reaction between 2‐substituted ethyl 2,5‐dihydro‐5‐oxoisoxazole‐4‐carboxylates (2a,b) and heterocyclic amines 1, 4, and 6, having the amino group in position 2 with respect to the nuclear nitrogen afforded fused pyrimidines 3, 5, and 7.
Synthesis and structure of 2,3,3a,4,9,9a‐hexahydro‐3,9a‐epoxy‐1H‐cyclopenta[b]quinoline and 5,7‐dibromo‐2,3,3a,4,9,9a‐hexahydro‐3,9a‐epoxy‐1H‐cyclopenta[b]quinoline
Authors: Jedrzejas Marek J. , Baker Ronald J. , Sheibley Fred A. , Oplinger Fred K. , Towns Robert L. R. 
Published: March 2009

AbstractA novel fused oxonorbornyl ring system synthesized by reaction of substituted aniline and methacrolein dimer in acidic media has been characterized by single crystal X‐ray diffraction. Two such structures are reported herein. These compounds represent the first reported structures of fused oxonorbornyl derivatives.
The structure of new cis and trans 3′‐phenyl‐3′,3a′,4′,5′,6′,7a′‐hexahydro‐2,1‐benzisoxazole‐7a′‐spiro‐2‐(3‐phenylaziridine)
Authors: Diaz Eduardo , Barrios Héctor , Yuste Francisco , Aguilera José Luis , Reynolds William F. , Van Calsteren Marie Rose , Jankowski Christopher 
Published: March 2009

AbstractThe reaction of dibenzalcyclohexanone with hydroxylamine hydrochloride afforded three compounds 1–3 including the aziridine 3 showing a 3′,3a′‐trans configuration. Now we report on the isolation of a new aziridine 4, possessing a 3′,3a′‐cis configuration. Its structure was deduced by 2D nmr and single crystal X‐ray diffraction studies.
Synthesis of 2‐substituted 5‐(1,3‐dithiolan‐2‐ylidene)‐1,3‐dioxane‐4,6‐dione derivatives
Authors: Jung Ji Hun , Kim Jae Nyoung , Ryu Eung K. 
Published: March 2009

AbstractSome 2‐substituted 5‐(1,3‐dithiolan‐2‐ylidene)‐1,3‐dioxane‐4,6‐dione derivatives 3 were prepared from the condensation reaction of 1,3‐dithiolan‐2‐ylidenemalonic acid (2) with carbonyl compounds in 40–93% yields.
Synthesis of dibenzocrown ethers with pendent amide groups
Authors: Kasprzyk Stanislaw P. , Bartsch Richard A. 
Published: March 2009

AbstractSynthetic routes to twenty six crown ether compounds with pendent amide, N‐alkylamide, or N,N‐dialkyl‐amide groups are reported. The new crown ether compounds are based on sym‐dibenzo‐16‐crown‐5‐oxyacetamide and sym‐(propyl)‐dibenzo‐16‐crown‐5‐oxyacetamide and are obtained in high yields.
Synthesis of 1,3‐disubstituted‐2‐amino‐5‐hydroxyindoles by reductive aromatization
Authors: Player Mark R. , Sowell J. Walter 
Published: March 2009

AbstractReductive aromatization and demethylation of 1,3‐disubstituted‐2‐amino‐5‐oxo‐7a‐methyl‐5,7a‐dihydroindoles with zinc, pyridine and a trace of water yields 1,3‐disubstituted‐2‐amino‐5‐hydroxyindoles. Simple derivatives of the 5‐hydroxy substituent are described.
Substituted γ‐lactones. Some observations on the synthesis and reactivity of 4‐aroyl‐3‐hydroxy‐2(5H)‐furanones
Authors: Zimmer Hans , Palmer‐Sungail R. , Ho Douglas , Amer Adel 
Published: March 2009

AbstractThe reaction pathway towards formation of 4‐aroyl‐3‐hydroxy‐2(5H)‐furanones 1 from the base catalyzed reaction between an acetophenone, diethyl oxalate and formaldehyde was investigated. If methoxide was used as base, a transesterification was found to occur in the first step, while a side reaction, namely the retro Claisen reaction, was in competition with the desired lactone formation in the second step. The nature of the solvent and the acidic character of 1 as well as the basicity of the aminoarylene were found to have a profound influence on the course of the reaction of 1 with aminoarylenes.
Pyrrolo[2,1‐c][1,4]benzoxazepines. 2. Synthesis of 5‐phenyl derivatives
Authors: Kapples Kevin J. , Effland Richard C. 
Published: March 2009

AbstractA series of 5‐phenylpyrrolo[2,1‐c][1,4]benzoxazepines with basic substituents at the 11‐position has been synthesized utilizing a nucleophilic aromatic fluoride displacement‐cyclization. Piperidinyl derivatives were prepared by Vilsmeier formylation of the key 1‐[(2‐fluorophenyl)phenylmethyl]pyrrole (4) followed by addition of a piperidinyl Grignard reagent and cyclization of the resulting carbinol. A (dimethylamino)methyl derivative was prepared via an analogous cyclization of α‐(dimethylamino)methyl‐1‐[(2‐fluorophenyl)phenyl‐methyl]‐1H‐pyrrole‐2‐methanol (10), obtained by the Hoeben‐Hoesch acylation of 4 with chloroacetonitrile, addition of dimethylamine to the resulting α‐chloroketone 8, and reduction of the α‐(dimethylamino)ketone 9 with sodium borohydride to give 10.
Diels‐alder reactions of 3‐(2‐nitrovinyl)indoles: Formation of carbazoles and bridged carbazoles
Authors: Noland Wayland E. , Konkel Michael J. , Tempesta Michael S. , Cink Russell D. , Powers Dawn M. , Schlemper Elmer O. , Barnes Charles L. 
Published: March 2009

AbstractThe Diels‐Alder reactions of 1‐substituted‐3‐(2‐nitrovinyl)indoles 3 with quinones and acetylenes give aromatized 1:1 adducts (‐ nitrous acid) (1) or (‐ nitrous acid, ‐2 hydrogens) 2,5. Likewise, dimerization (‐2 nitrous acids) of 3 gives aromatized 2‐(3‐indolyl)carbazoles 4. In contrast, 3 reacts with maleimides 6 to give 1:2 adducts (‐ nitrous acid or ‐2 hydrogens) 10 and 11, respectively, along with smaller amounts of 1:1 adducts (‐ nitrous acid, ‐2 hydrogens; or ‐4 hydrogens) 12 and 13, respectively. A mechanism for formation of the nitro products 11 and 13 is discussed. A 1:2 adduct (‐2 hydrogens) 19 was also obtained from a Diels‐Alder reaction between maleimide and the vinylindole produced in situ by condensing 1‐methylindole with acetone. The stereochemisty of this 1:2 adduct has been determined by X‐ray crystallography.
Studies on quinones. Part 25. Synthetic approaches to 6,9‐dioxygenated‐benzazepinones
Authors: Valderrama J. A. , Pessoa‐Mahana H. , Tapia R. 
Published: March 2009

AbstractThe Schmidt and Beckmann rearrangement of 3,4‐dihydro‐4,4‐dimethyl‐1(2H)‐naphthalenones bearing oxygenated groups at the 5,8‐positions, and some of their oximes are reported. Depending upon the structure of the substrates and the reaction conditions 4,5‐dihydro‐3H‐naphth[1,8‐cd]isoxazol, benzazepin‐2‐one and 5,6‐dihydro‐7H‐tetrazolo[1,5‐a][2]benzazepine derivatives were generated.
Manganese(III)‐mediated free‐radical cyclization of acitve methylene compounds, alkenes and molecular oxygen. Syntheses of sulfur‐ and phosphorus‐containing 1,2‐dioxan‐3‐ols
Authors: Qian Chang‐Yi , Nishino Hiroshi , Kurosawa Kazu 
Published: March 2009

AbstractThe reactions of β‐keto sulfoxide, β‐keto sulfones, or β‐keto phosphinate with 1,1‐disubstituted ethenes in the presence of manganese(III) acetate and molecular oxygen yielded 4‐phenylsulfinyl‐, 4‐phenylsulfonyl‐, or 4‐phosphinoyl‐1,2‐dioxan‐3‐ols 3 in moderate‐to‐good yields. m‐Chloroperbenzoic acid oxidation of 4‐phenylsulfinyl‐1,2‐dioxan‐3‐ols gave the corresponding 4‐phenylsulfonyl derivatives. The temperature dependence of the reactions was observed and the stereochemistry of the 1,2‐dioxan‐3‐ols are discussed.
Synthetic studies on indoles and related compounds. XXXI. Chemical confirmation of the synthetic route for the benz[f]indole skeleton and its application
Authors: Watanabe Toshiko , Miyagi Chiemi , Murakami Yasuoki 
Published: March 2009

AbstractTo confirm the structure of ethyl 9‐methoxybenz[f]indole (8a) prepared from ethyl pyrrole‐2‐carboxylate (4) via a new synthetic route, the following chemical correlation work was performed. Ethyl 9‐methoxybenz[f]in‐dole (8a) was converted to 1‐benzyl‐3‐methyl‐5,6,7,8‐tetrahydrobenz[f]indole (25), which was alternatively and authentically synthesized from ethyl 3‐methylpyrrole‐2‐carboxylate (11). On the basis of the established route to the benz[f]indole nucleus, two representative benz[f]indoles, benz[f]indole (1) and 4,9‐dioxobenz[f]indole (26) were synthesized.
Synthesis of novel isoquinoline derivatives as potential CNS‐agents
Authors: Bonnaud B. , Carlessi A. , Bigg D. C. H. 
Published: March 2009

AbstractA series of 4‐aminomethyl‐1,2,3,4‐tetrahydroisoquinoline derivatives were prepared as potential CNS‐agents acting via amino‐acid neurotransmitter systems. The compounds were synthesized from 1,2,3,4‐tetra‐hydro‐1‐oxoisoquinoline‐4‐carboxylic acids obtained by dipolar cycloaddition reactions of imines with homo‐phthalic anhydride. Among the compounds tested 5c and 5m showed sub‐micromolar affinity for the NMDA receptor and represent a structurally novel class of ligand for this site.
Polycyclic pyridazines. II [3]. Synthesis of pyrazolo[4′,3′:5,6]pyrido[2,3‐d]pyrid‐azine derivatives from dimethyl pyrazolo[3,4‐d]pyrid‐azine‐5,6‐dicarboxylates as the key intermediates
Authors: Tominaga Yoshinori , Luo Jiann‐Kuan , Castle Lyle W. , Castle Raymond N. 
Published: March 2009

AbstractThe synthesis of the novel pyrazolo[4′,3′:5,6]pyrido[2,3‐d]pyridazine ring system and some of its derivatives has been accomplished such as 4‐amino‐1‐phenyl‐5,8‐dioxo‐, 4‐amino‐5,8‐dioxo‐, 1‐phenyl‐5,8‐dioxo‐, 5,8‐dioxo‐, 5,8‐dichloro‐1‐phenyl‐, 5‐ethoxy‐1‐phenyl‐ and 8‐ethoxy‐1‐phenylpyrazolo[4′,3′:5,6]pyrido[2,3‐d]pyrid‐azines.
A convenient synthesis of the thieno[3,2‐c]pyridine nucleus
Authors: Wikel James H. , Denney Michael L. , Vasileff Robert T. 
Published: March 2009

AbstractThe unsubstituted thieno[3,2‐c]pyridine ring system was prepared from thiophene‐3‐carboxaldehyde in 4 steps. The sequence is suitable for scale‐up.
Nucleic acid related compounds. 81. Syntheses of 9‐(3‐deoxy‐β‐D‐threo‐pentofuranosyl)adenine, the core nucleoside of the extraordinarily selective antibiotic agrocin 84, and simplified structural component analogues
Authors: Vinayak Ravi , Hansske Fritz , Robins Morris J. 
Published: March 2009

AbstractAlternative syntheses of 9‐(3‐deoxy‐β‐D‐threo‐pentofuranosyl)adenine (4), the core nucleoside of agrocin 84 [and its 2′‐deoxy threo isomer 5] were devised: (1) direct conversion of 9‐(β‐D‐arabinofuranosyl)adenine into 9‐(2,3‐anhydro‐β‐D‐lyxofuranosyl)adenine and regioselective opening of its oxirane ring with sodium borohy‐dride to give 4 and 5(˜7.5:1); (2) treatment of adenosine with sodium hydride and 2,4,6‐triisopropylbenzene‐sulfonyl chloride, and subjection of the resulting 2′(3′)‐sulfonates to the reductive [1,2]‐hydride shift rearrangement with lithium triethylborohydride to give 4 and 5 (˜ 2:1); and (3) subjection of the phenoxythiocar‐bonyl esters of 9‐[2(3),5‐bis‐O‐(tert‐butyldimethylsilyl)‐β‐D‐arabinofuranosyl]adenine to Barton deoxygenation, and deprotection to give 4 and 2′‐deoxyadenosine (˜5:1). Methods (2) and (3) gave lower yields. Syntheses of simplified 6‐N‐ and 5′‐O‐adenosine phosphoramidate model compounds were explored to examine potential access to such features in the structure proposed for agrocin 84.
Triazolines 24. Permanganate‐catalyzed low temperature thermolysis of 5‐(4‐pyridyl) substituted 1,2,3‐triazolines
Authors: Kadaba Pankaja K. , Parmley Gordon , Crooks Peter A. , Agha Bushra 
Published: March 2009

AbstractPotassium permanganate oxidation of 1‐aryl‐5‐(4‐pyridyl)‐1,2,3‐triazolines I in a benzene‐water two‐phase system using the phase‐transfer catalyst tetrabutylammonium chloride yields the corresponding 1H‐1,2,3‐tri‐azoles II. However, when the reaction is run in a single phase in anhydrous benzene alone, the products are not triazoles, but imines III that can normally be obtained only by high‐temperature thermolysis of the tri‐azolines. The presence of both potassium permanganate and tetrabutylammonium chloride to yield the benzene soluble tetrabutylammonium permanganate ion pair appears essential for imine formation, although only in catalytic amounts. Thus a reaction pathway is proposed, which involves the initial coordination of the pyridyl nitrogen with the manganese atom of the permanganate ion leading to IV, followed by loss of nitrogen and regeneration of the permanganate ion via the dihydropyridine intermediates, V and VI, to yield the enamine VII, which tautomerizes to the imine III. Supportive evidence for the formation of IV is derived from the failure of 1,5‐diaryl‐ and l‐aryl‐5‐(3‐pyridyl)triazolines to yield the respective imines; they lack the structural requirements necessary to comply with the proposed mechanism, and are recovered unchanged. Unlike the high temperature pyrolysis, the permanganate catalyzed low temperature thermolysis reactions provide cleaner products in better yields. Thus, the low temperature thermolysis may afford a route for the synthesis of clean samples of l‐arylimino‐l‐ethyl‐4‐pyridines, especially when the triazolines are on hand.
Purines. XIV. Synthesis and properties of 8‐nitroxanthine and its N‐methyl derivatives
Authors: Mosselhi Mosselhi A. , Pfleiderer Wolfgang 
Published: March 2009

AbstractXanthine (1) and its N‐methyl derivatives 2–16 have been nitrated to the corresponding 8‐nitro derivatives 17–32 under different reaction conditions. Nitration in glacial acetic acid with nitric acid works well with the N‐7 unsubstituted and some of the 9‐methylxanthines, respectively, whereas the 7‐methylxanthine derivatives react best with nitronium tetrafluoroborate in sulfolane or glacial acetic acid. The 8‐nitro group can be displaced nucleophilically to form 8‐chloro‐, 33, 34, 8‐ethoxy‐, 35,36, and uric acid derivatives 37–40, respectively. The newly synthesized 8‐nitroxanthines have been characterized by elemental analyses, pK‐determinations and uv and 1H‐nmr spectra.
Preparation of oxazolidin‐2‐ones by oxidation of oxazolidine‐2‐thiones. A proton magnetic resonance structural study
Authors: Moreno‐Mañas Marcial , Padros Imma 
Published: March 2009

AbstractThe preparation of a series of oxazolidine‐2‐thiones, both homochiral and racemic, as well as their oxidation to oxazolidin‐2‐ones is reported. X‐Ray and pmr studies have showed that the stereochemical integrity of the starting aminoalcohol is maintained.
Pyrimidines. 24. Analogues and derivatives of 2‐amino‐5‐bromo‐6‐phenyl‐4(3H)‐pyrimidinone (ABPP)
Authors: Fan Junyuan , Cheng C. C. 
Published: March 2009

AbstractPreparation of a number of derivatives of 2‐amino‐5‐bromo‐6‐phenyl‐4(3H)‐pyrimidinone (ABPP) including the 2‐dialkylaminoalkylamino‐, 2‐hydroxyalkylamino‐, 2‐ethoxycarbonylamino‐ and 2‐alkylaminocarbonyl‐amino‐ groups substituted on the pyrimidine ring as well as preparation of 1‐(alkylaminoalkyl)‐4,6‐dioxo‐8‐phenyl‐2,3,4,6‐tetrahydro‐1H‐pyrimido[1,2‐α]pyrimidines and 3,5‐dioxo‐7‐phenyl‐1,2,3,5‐tetrahydroimidazo‐[1,2‐α]pyrimidines with or without the bromo‐substitution are reported.
Synthesis of a new series of 8‐substituted‐2,8‐diazaspiro[4.5]decan‐3‐ones
Authors: Cignarella Giorgio , Villa Stefania , Barlocco Daniela 
Published: March 2009

AbstractA new series of 8‐substituted‐2,8‐diazaspiro[4.5]decan‐3‐ones has been synthesized and tested inin vitroandin vivoassays predictive for cholinergic activity, in comparison with the muscarinic agent RS‐86. Preliminary pharmacological data indicate that the compounds are devoid of significant cholinergic properties.
A highly regioselective reaction of N‐fluoropyridinium salts with stabilized sulfur, oxygen, and nitrogen nucleophiles: A convenient route to 2‐substituted pyridines
Authors: Kiselyov Alexander S. , Strekowski Lucjan 
Published: March 2009

Abstract2‐Substituted pyridines are efficiently obtained by the reactions of N‐fluoropyridinium tetrafluoroborate or triflate with anions derived from benzenethiols, phenols, azoles, cyanamide, and with azide anion. The results are consistent with a nucleophile addition at the position 2 of the N‐fluoropyridinium cation as the major reaction pathway.
Synthesis of imidazo[1,2‐b]pyridazines: Fenbendazole, oxifenbendazole analogs and related derivatives
Authors: Mourad Alaa E. , Wise Dean S. , Townsend Leroy B. 
Published: March 2009

AbstractA series of imidazo[1,2‐b]pyridazines has been prepared and evaluated for macrofilaricidal activity against Brugia pahangi or Acanthocheilonema viteae infections in jirds. The imidazo[1,2‐b]pyridazine analogs of fen‐bendazole and oxifenbendazole are reported. In addition, several 6‐aminoimidazo[1,2‐b]pyridazine derivatives have been prepared. None of these compounds possessed significant activity against human cytomega‐lovirus (HCMV) or filarial infections.
Synthesis of 2′‐deoxyguanosine containing a N2‐polyamine
Authors: Ramasamy Kanda S. , Bakir Farid , Baker Brenda , Dan Cook P. 
Published: March 2009

AbstractThe synthesis of benzylated N2‐(4,7,10,13‐tetraazatridec‐1‐yl)‐2′‐deoxyguanosines 4 was accomplished by a key nucleophilic reaction of the novel unsymmetrical polyamine 2, with 3′,5′‐O‐(tetraisopropyldisiloxane‐1,3‐diyl)‐2‐chloro‐2′‐deoxyinosine (1).
The synthesis of several imidazo[4,5‐d]isothiazoles. Derivatives of a new ring system
Authors: Swayze Eric E. , Townsend Leroy B. 
Published: March 2009

AbstractSeveral derivatives of the new imidazo[4,5‐d]isothiazole ring system have been synthesized from the appropriately substituted isothiazolediamines. The reaction of 3‐methyl‐4,5‐diaminoisothiazole (4a) with diethoxy‐methyl acetate gave a low yield of 3‐methylimidazo[4,5‐d]isothiazole (5a). However, the analogous reaction of 4,5‐diaminoisothiazole (4b) with diethoxymethyl acetate failed to yield the parent imidazo[4,5‐d]isothiazole ring system. The diamines 4a and 4b were readily cyclized with thiocarbonyldiimidazole to give the unstable thiones 6a and 6b, which were alkylated in situ to afford good yields of the corresponding 5‐methylthioimidazo[4,5‐d]isothiazoles 7a and 7b, respectively. Neither of these compounds could be reduced to the corresponding 5‐unsubstituted derivatives via treatment with Raney nickel. To the best of our knowledge, this is the first report of the imidazo[4,5‐d]isothiazole ring system.
Azidocarbonyl‐substituted cubanoureas
Authors: Gilardi Richard , George Clifford , Karle Jerome , Eaton Philip E. , Rao Munagala 
Published: March 2009

AbstractDespite the angular strain associated with the assembly of small rings, 1,2‐diisocyanatocubane reacts with trimethylsilyl azide under mild conditions to form a hexacyclic ring assembly that contains an imidazolidone ring fused to one edge of cubane. This compound was identified as an azidocarbonyl‐substituted cubanourea by means of X‐ray crystal structure analysis of the nitro‐derivative, the energetic compound N‐azidocarbonyl‐N1‐nitrocubanourea.
Cyclopentene carbocyclic nucleosides related to the antitumor nucleoside clitocine and their conversion to 8‐Aza‐neplanocin analogues. Synthesis and antiviral activity
Authors: Marquez Victor E. , Lim Benjamin B. , Driscoll John S. , Snoek Robert , Balzarini Jan , Ikeda Satoru , Andrei Graciela , De Clercq Erick 
Published: March 2009

AbstractSynthesis of the cyclopentene carbocyclic analogue of the naturally occurring nucleoside clitocine (1) is reported. Starting with racemic cyclopentenylamine (10), the heterocyclic moieties of the clitocine analogue 4 and related 1,6‐dihydro‐6‐oxo, 5, and 2‐amino‐1,6‐dihydro‐6‐oxo, 6, analogues were constructed. These compounds were respectively converted to 8‐aza‐neplanocin A (7), 8‐aza‐neplanocin D (8, the inosine analogue), and the corresponding 8‐aza‐guanosine analogue 9 after reduction of the nitro group followed by nitrous acid cyclization. Extensive antiviral evaluation revealed that only 8‐aza‐neplanocin A (7) had enough antiviral activity to warrant further studies. This compound showed weak antiviral activity against HSV‐1, HSV‐20 and the thymidine kinase deficient (TK‐) HSV‐1. However, it displayed good antiviral activity against human cytomegalovirus (HCMV) at a concentration of 0.40–2.50 μg/ml, well below the cytotoxicity threshold. This activity profile is consistent with a mechanism of action involving the inhibition of the enzyme adenosylhomo‐cysteine hydrolase.