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5-Alkenyl hydantoins and alkenyl spirohydantoins are converted into bicyclic and tricyclic hydantoins, under indirect electrochemical conditions, generating the phenylselenyl cation in situ. The reactions proceeded in good to exelent yields. The influence of electrochemical conditions on regio- and diastereoselectivity of the selenocyclization reactions is investigated.

In the present paper, we report an expedient total synthesis of triciribine, a tricyclic 7-deazapurine nucleoside and protein kinase B (AKT ) inhibitor, in 35% overall yield. Our synthesis route features a highly regioselective substitution of 1-N-Boc-2-methylhydrazine and a trifluoroacetic acid catalyzed one-pot transformation which combined the deprotection of the tert-butylcarbonyl (Boc) group and ring closure reaction together to give a tricyclic nucleobase motif.

The Cu(I)-catalyzed Huisgen [3+2] cycloaddition is the basis of click chemistry to synthesize triazole derivatives by coupling azides with ethynyl blocks. In the development of new compounds inspired by bioactive natural products, the synthesis of new oxazole building blocks containing azide moiety and coupling them with aromatic alkynes via triazole linker is described. These oxazole building blocks are synthesized using amino acids as chiral and inexpensive starting materials. Using this approach, 16 new triazole-oxazole hybrids were synthesized., This research was supported by CSIC Grupos Nº 654, PEDECIBA Química, co-financed by the EU Research Potential (FP7-­REGPOT-2012-CT2012-31637-IMBRAIN), the European Regional Development Fund (FEDER), the Spanish Instituto de Salud Carlos III (PI11/00840), and the Spanish MINECO (CTQ2011-28417-C02-01/BQU). G.V. would like to thank ANII (Agencia Nacional de Investigación e Innovación) for the award of a doctoral fellowship under the grant BE_POS_2010_1_2422.

A series of 4-arylamino-8-(alkyl or aryl)hydrazidepyrimido[5,4-d]pyrimidines was obtained efficiently from 6-carbohydrazonamidepurines by reaction with piperidine. The 6-carbo-hydrazonamidepurines were generated selectively by the reaction of 6-imidatopurine with hydrazides under acidic conditions., University of Minho and Fundação para a Ciência e Tecnologia (FCT) for financial support [project noF-COMP-01-0124-FEDER-022716 (ref. FCT PEst-/QUI/UI0686/2011) FEDER-COMPETE, FCT-Portugal, a PhD grant awarded to Ana Bacelar (SRFH/BD/24959/2005)]. The NMR spectrometer (Bruker 400 Avance III) is part of the National NMR Network supported with funds from FCT.

A high-yielding general synthesis of imidazophosphor ester based tetrazolo[1,5-b]pyridazines is described. A conjugated reaction between 3,6-diazidopyridazine and different types of phosphonyl carbanion reagents followed by intramolecular cyclization afforded the target products, by using sodium ethanolate solution as a reaction medium. Among the products, five compounds, at a dose of 50 mg per kilogram body weight, showed a notable antinociceptive and anti-inflammatory activity without toxic side-effects.

A general synthetic route to prepare all four carboline regioisomers by photostimulated cyclization of anilinohalopyridines is described. The methodology affords various substituted carbolines in good to excellent yields. In the case of α-carbolines, the S(RN)1 methodology complements previously reported palladium-catalyzed cyclization approaches. Fil: Laha, Joydev K.. Harvard Medical School; Estados Unidos Fil: Barolo, Silvia Maricel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina Fil: Rossi, Roberto Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina Fil: Cuny, Gregory D.. Harvard Medical School; Estados Unidos

A series of 2,6,9-substituted adenines were obtained from the easily accessible 5-amino-4-cyanoformimidoyl imidazoles 1, acetic and benzoic anhydrides and primary alkyl amines in a three-steps sequence. Acylation of 1 followed by addition of the amine led to the intermediates 5-amino-4-(N-acyl)formamidino imidazoles 4/5, under mild conditions. Cyclization of 4/5 under reflux in ethanol led to the desired substituted adenine. A preliminary stepwise study led to the development of three general and efficient one-pot methods for the synthesis of adenine derivatives. The one-pot three-step reaction in the presence of DMAP was the most convenient syn-thetic approach., The authors gratefully acknowledge the financial support by the University of Minho and Fundacao para a Ciencia e Tecnologia.

1-Silaindenes are prepared starting from (2-vinylphenyl)hydrosilanes and alkynes through a ruthenium-catalyzed hydrosilylation-ring-closing-metathesis sequence. The method is successfully applied to the synthesis of molecules containing multiple silaindene units.

5-(5-Amino imidazole-4-yl)-1,2,4-triazol-3-ones were obtained under mild experimental conditions from 5-amino-4-(N-ethoxycarbonyl) cyanoformimidoyl imidazoles and hydrazine in a rapid one-pot reaction. When hydroxylamine hydrochloride was used, in the presence of base, the corresponding 1,2,4-oxadiazol-5-ones were isolated. An equally fast reaction occurred when 5-amino-4-(N-acetyl/benzoyl) cyanoformimidoyl imidazoles were combined with hydrazine to give 5-(5-amino imidazole-4-yl)-1,2,4-triazoles., The authors gratefully acknowledge the financial support by the University of Minho and Fundacao para a Ciencia e Tecnologia (project PRAXIS/C/QUI/45391/2002).

The synthesis of a series of substituted 9H-carbazoles by the photostimulated SRN1 substitution reactionwith diarylamines as starting substrate was performed. The diarylamines were obtained by two approaches,the Pd-catalyzed reactions (Buchwald-Hartwig) or Cu-catalyzed reactions of 2-haloanilines with aryl halides, or 2-bromoiodobenzene with anilines, with moderate to very good isolated yields (45-89%).Through an intramolecular C-C bond formation of diarylamines by the SRN1 mechanism, Carbazoles were achieved. These reactions proceeded synthetically in very good to excellent yields (81-99%) in liquid ammonia and DMSO. The reaction of N-(2-bromophenyl)-2-phenylbenzenamine gave 1-phenyl-9H-carbazole (38%) and the isomer 9H-tribenz[b,d,f]azepine (58%). By using this methodology, 9Hcarbazoles, substituted 9H-carbazoles, benzocarbazoles, and even 3,3′-bi(9H-carbazole) were obtained by a double SRN1 reaction with benzidine. Fil: Buden, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina Fil: Vaillard, Victoria Anahi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Martín, Sandra Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina Fil: Rossi, Roberto Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina

Nicholas reactions on 2,7-dioxygenated naphthalenes give C-1 monosubstitution and C-1/C-8 disubstitution in most cases. From gamma-carbonyl cation monocondensation product 3b or alkyne-unsubstituted dicondensation product 4a, cyclohepta[de]naphthalenes bearing no substituents, gem-dimethyl substituents, and a ketone function, and the rearranged abietane framework of microstegiol may be prepared.

Silole skeletons are constructed by ring-closing olefin metathesis of silicon-tethered dienes and trienes. A silicon-tethered enyne is also converted to a 2-alkenyl-1-silaindene via ruthenium-catalyzed ring-closing enyne metathesis.

Ring closure via microwave-assisted intramolecular OMs displacement by a γ-OBn group (O-nucleophilic attack) in protected polyhydroxylated N-Boc-thiazolylalkyl amines afforded C-furanosides (37-81%) featuring a chiral thiazolylmethylamino side chain, which, upon thiazole to carboxylate (through aldehyde) transformation, furnished enantiopure C-furanosyl glycines.

A novel stereocontrolled approach has been developed for the syntheses of tashiromine and epitashiromine alkaloids from cyclooctene β-amino acids. The synthetic concept is based on the azetidinone opening of a bicyclic β-lactam, followed by oxidative ring opening through ring C–C double bond and reductive ring-closure reactions of the cis- or trans-cyclooctene β-amino acids.

A simple and stereospecific synthesis of both (R)- and (S)-GABOB has been developed. The synthetic approach involves the conversion, through organoselenium intermediates, of commercially available ethyl (R)- and (S)-4-chloro-3-hydroxybutyrate into a protected 1,2-amino alcohol with retention of the original configuration.

New convenient methods for the synthesis of 1,2,3-thiadiazole, 1,3,4-thiadiazine, and 1,2,5-triazepine derivatives are reported. In the heterocyclization process, the reactivity of 1-thia-4-aza-1,3-butadiene system of syn-2-phenylhydrazono-3-oxothiobutanoic acid anilides was exploited.

Whereas the biomimetic oxidative N-dealkylation of tertiary amines with t-BuOOH and an iron(III) tetraphenylporphyrin typically proceeds by an electron transfer (ET) route, a radical H-atom transfer (HAT) route has been found to operate with N-benzylaziridine (1), an amine that is fairly resistant towards one-electron oxidation for steric reasons. New mechanistic information is presented in favour of this radical route, and the exclusive formation of the dimeric product N,N′-dibenzylpiperazine (2) is explained in the light of the Baldwin's rules. Flash photolysis data provide a rate constant of 1.7 × 105 s−1 for the ring opening of the aziridine radical (1.) to the imine radical (4.) in the early stages of the process leading to 2. Semiempirical calculations indicate the ring-opened radical 4. to be more stable than 1.. Copyright © 2002 John Wiley & Sons, Ltd.

Acylation of 2-aminothiobenzamide or 2-methylaminothiobenzamide with substituted benzoyl chlorides has been used to synthesise the corresponding 2-benzoyl-aminothiobenzamides whose subsequent sodium methoxide-catalysed ring closure gives the corresponding quinazoline-4-thiones. These compounds were characterised by means of their 1H- and 13C-NMR spectra. The preferred tautomeric form of selected compounds has been discussed on the basis of their 13C-NMR, IR and Raman spectra. It has been found that in the given medium 1-methyl-quinazoline-4-thiones undergo a replacement of the sulphur substituent by oxygen giving 1-methyl-quinazoline-4-ones. In strong acid media, 2-benzoylaminothiobenzamide is cyclised through its sulphur atom to give 2-phenylbenzo[d-1,3]thiazin-4-one.

This account describes our studies on the synthesis of natural products that contain cyclic ethers in their structures. An overview of the main methodologies is presented and several total syntheses developed by the group are described. We also discuss new applications based on the use of Prins and Nicolas reactions as key steps in the preparation of oxygenated heterocyclic compounds., This research was supported by the Spanish MINECO, co-financed by the European Regional Development Fund (ERDF) (CTQ2011- 28417-C02-01/BQU and CTQ2011-22653) and the IMBRAIN project (FP7-REGPOT-2012-CT2012-31637-IMBRAIN), which is funded under the Seventh Framework Programme (CAPACITIES).

This Account describes our work on highly electrophilic γ-carbonyl cations featuring propargyldicobalt cations, cycloheptynedicobalt complexes, and the interconnection between the two systems. 1 Introduction 2 γ-Carbonyl Cations via Iron Allyl Cations 3 γ-Carbonyl Cations via Propargyldicobalt Cations 3.1 Synthesis of Velloziolide 3.2 Synthesis of Microstegiol 4 Synthesis of Cycloheptynedicobalt Complexes 4.1 Synthesis via γ-Carbonyl Cations 4.2 Cycloheptynedicobalt Complexes via [4+3] Cycloaddition Reactions 4.3 Cycloheptynedicobalt Complexes via Ring-Closing Meta­thesis 4.4 Cycloaddition Reactions on Cycloheptynedicobalt Complexes 4.5 Cycloheptynedicobalt Complexes via Intramolecular ­Nicholas Reactions 5 Dehydrotropylium Ion Co2(CO)6 Complex 6 Final Comments

Blatters radical, 1,3-diphenyl-1,4-dihydro-1,2,4-benzotriazin-4-yl (1a, R =H), and several of its C-7 substituted analogues (R =CF3, Cl, Br, I, Me, OMe) were prepared in good-to-excellent yields through catalytic oxidation of the corresponding amidrazones by using palladium-on-carbon (1.6 mol%) and 1,8-diazabicyclo[5.4.0]undec-7-ene (0.1-1.0 equiv) in air. The reaction conditions were suitable for the preparation of Blatters radical on a one-gram scale in up to 87% yield. © Georg Thieme Verlag Stuttgart. 12 2075 2079 Cited By :36

5 pages.-- et al., In search for novel heterocyclization processes, the intramolecular Pd-mediated allylic alkylation of homoallyl hydroxyl­amines is described. Depending on both the reaction conditions and the substrates, cis- or trans-3-substituted-5-vinyl isoxazolidines are preferentially obtained. The corresponding starting materials for the cyclization step are readily obtained through cross-metathesis of the easily accessible unsubstituted homoallyl hydroxylamines., This study was supported by the Ministerio de Educacion y Ciencia (MEC) and FEDER Program (Madrid, Spain, project CTQ2004-0421/BQU) and the Gobierno de Aragón (Zaragoza, Spain). V.M. thanks MEC for a FPU predoctoral grant.

Ring closure and ring opening reactions are in many cases useful synthetic procedures in organic chemistry. They allow the preparation of complex molecules with high stereoselectivity and good yields. Mechanistic and theoretical studies have been carried out on the transformation of 2-aminopyrimidines into imidazo[1,2-c]pyrimidines and guanidines, respectively, through ring closure and ring opening reactions, as well as the transamidation reactions through the ring closure and ring opening of guanidine derivatives, which constitute novel synthetic methods. Sepulveda Arques, Jose, Jose.Sepulveda@uv.es

A concise and inexpensive route to 2-cyano aziridine-2-carboxylates and 2,2-dicyano aziridines is reported by reaction of the easily obtainable corresponding α,β-unsaturated nitriles with sulfonyloxycarbamates in the presence of calcium oxide.

Thiazolidine beta-enamino derivatives possessing a 5-substituted acetate substituent were chemoselectively reduced to corresponding alcohols, or new condensed 2-alkylidenethiazolidines. The method is based on the resistance of an enaminone fragment to reduction by metal hydrides.

Hexacarbonyldicobalt complexes of cycloheptenynes (4) may be prepared by the ring closing metathesis of the corresponding acyclic dienes (2) using Grubbs' catalyst, (Cy3P)(2)Cl2Ru=CHPh. A cyclooctenyne complex (8) has also been prepared in the strictly analogous manner.

Butyne-1,4-diether hexacarbonyldicobalt complexes 1 undergo Lewis acid mediated 4+3 cycloadditions with allylsilanes, incorporating halide from the Lewis acid to give halocycloheptynes 3, 6, 7. A phenyl group may be incorporated in place of the halogen (to give 8) by use of benzene as solvent and with B(C6F5)(3) as the Lewis acid; chlorobenzene and toluene also participate in the process.

Rates of cyclisation of 1 ,I -bis(phenylsulphonyl) carbanions bearing distal leaving groups have been determined. The response of the system to solvent effects and to leaving group is similar to that in i n termolecu la r nu Cleo p h i I ic su bst i t u t i on. The system is very sensitive to the size of the ring formed; for iodides in ethanol the ratios for ring sizes 3: 4 : 5 : 6 : 7 are 1 : 1 .I x 10E-5: 1 .O x 10E-2: 1.6 x 1OE-6: 7.3 x 1OE-1O. The contribution of strain in the product to the enthalpy of activation is slight and inconsistent; the entropy of activation for cyclopropane formation is so favourable as to make this by far the most rapid process observed.