Wideband dual sphere detector of gravitational waves

We present the concept of a sensitive and broadband resonant mass gravitational wave detector. A massive sphere is suspended inside a second hollow one. Short, high-finesse Fabry-Perot optical cavities read out the differential displacements of the two spheres as their quadrupole modes are excited. At cryogenic temperatures, one approaches the standard quantum limit for broadband operation with reasonable choices for the cavity finesses and the intracavity light power. A molybdenum detector, of overall size of 2 m, would reach spectral strain sensitivities of 2x10-23Hz-1/2 between 1000 and 3000 Hz.

Highly efficient palladium-catalyzed Suzuki-Miyaura reactions of potassium aryltrifluoroborates with 5-iodo-1,3-dioxin-4-ones in water: an approach to alpha-aryl-beta-ketoesters

The high efficient palladium-catalyzed Suzuki-Miyaura reactions of potassium aryltrifluoroborates 3 with 5-iodo-1,3-dioxin-4-ones 2a-b in water as only solvent in the presence of n-Bu(4)NOH as base is reported. The respective 5-aryl-1,3-dioxin-4-ones 4a-n were obtained in good to excellent yields. The catalyst system provides high efficiency at low load using electronically diverse coupling partners. The obtained 2,2,6-trimethyl-5-aryl-1,3-dioxin-4-ones were transformed into corresponding alpha-aryl-beta-ketoesters 6 by reaction with an alcohol in the absence of solvent. (C) 2009 Elsevier Ltd. All rights reserved.

Synthesis of (2S)-isopropyl-5-alkynylpyrimidin-2-ones: precursors of beta-aminoacids

The efficient palladium-catalyzed Suzuki-Miyaura cross-coupling reaction of (2S)-isopropyl-5-iodo-2,3-dihydro-4(H)-pyrimidin-4-one with, arylethynyl-, heteroarylethynyl-, and alkylethynyltrifluoroborate salts is reported. The standard protocol was evaluated and optimized in order to gain access to suitable precursors of enantiopure 2-substituted beta-amino acids. The scope and limitations of this methodology are discussed. (C) 2010 Elsevier Ltd. All rights reserved.

Functionalization of (2S)-Isopropyl-5-iodo-2,3-dihydro-4(H)-pyrimidin-4-ones by a Suzuki-Miyaura Cross-Coupling Reaction Using Aryltrifluoroborate Salts: Convenient Enantioselective Preparation of alpha-Substituted beta-Amino Acids

A simple protocol for the Pd(OAc)(2)-catalyzed cross-coupling reaction of 1-benzoyl-(2S)-isopropyl-5-iodo-2,3-dihydro-4(H)-pyrimidin-4-ones with potassium aryltrifluoroborates was developed. The reaction is performed at 110 degrees C with a ligand-free catalyst. In all cases, complete conversion of the 1-benzoyl-(2S)-isopropyl-5-iodo-2,3-dihydro-4(H)-pyrimidin-4-ones and aryltrifluoroborates into the C-C coupling products was observed within 30-360 min. It is noteworthy that a large variety of groups present in the potassium aryltrifluoroborates (-CF(3), -OMe, -SEt, -CN, -CHO, -Cl, -Cbz, -NCbz, -OH, -CO(2)H) could be tolerated. Hydrogenation of the endocyclic double bonds in the Suzuki-Miyaura products followed by acid hydrolysis afforded highly enantioenriched alpha-aryl-substituted beta-amino acids.

Synthesis of 5-alkynyl-2,2,6-trimethyl-1,3-dioxin-4-ones and 1,4-disubstituted-1,2,3-triazoles

Herein we report an approach to the formation of 5-alkynyl-1,3-dioxin-4-ones using Suzuki-Miyaura cross-coupling reaction of potassium alkynyltrifluoroborate salts with 2,2,6-trimethy1-5-iodo-1,3-dioxin-4-one. The resulting 5-ethynyltrimethylsilyl-1,3-dioxin-4-ones obtained through the Sonogashira reaction were further reacted in a Cu(I)-catalyzed Huisgen azide-alkyne 1,3-dipolar cycloaddition to form functionalized 1,4-disubstituted-1,2,3-triazoles in good yields, using mild conditions and ultrasonic radiation to expedite the reaction. (C) 2011 Elsevier Ltd. All rights reserved.

A new synthesis of chiral aminoalkyloxazolecarboxylate esters from isoxazol-5(2H)-ones: the synthesis of almazoles A and B

2-(1-Aminoalkyl)oxazole-4 and 5-carboxylates are available, without detectable racemisation, by a sequence involving N-acylation of isoxazol-5(2H)one carboxylates with phthalimidoamino acids, photolysis of the acylated product, and hydrazinolysis. An application of the procedure to the synthesis of almazole A and B is described (C) 1998 Elsevier Science Ltd. All rights reserved.

The chemistry of 5-oxodihydroisoxazoles .19. The synthesis and photolysis of N-thioacylisoxazol-5(2H)-ones

5-Oxodihydroisoxazoles react with thiocarbonyl chlorides to afford N-thioacylisoxazol-5(2H)-ones which lose carbon dioxide under photochemical conditions and undergo intramolecular cyclisation of the iminocarbene to afford thiazoles, However, in some cases loss of carbon dioxide is accompanied by loss of sulfur, giving 1,3-oxazin-6-ones.

Antifungal activity of Imidazolidin-4-ones of the antimalarial primaquine

The 5-Isopropyl-3-[4-(6-methoxy-quinolin-8-ylamino)-pentyl]-2,2-dimethyl-imidazolidin-4-one (ValPQacet) was sinthesized through acylation of the anti-malarial primaquine with α-valine and subsequent reaction of the resulting -aminoamide with propanone (Sheme 1).Imidazolidin-4-ones of the anti malarial primaquine are being sinthesized to develop new variants in order to improve more effective treatments against malaria . Recently it has been observed that primaquine derivates could have effect in a new kind of yeast . To study the fungicidal activity against Candida albicans, Candida tropicalis, Issatchenkia orientalis, Sacharomyces cerevisae, the ValPQacet was put in the form of the hydrochloride salt. The minimal inhibitory concentration (MIC) could be determined for all yeast in the concentration range assayed. Also was determined MIC’s of primaquine hydrochloride salt for all yeast, and this shows that the parent drug is less active than our compound. Further studies are being performed to determine viability and cellular injury with this drugs.

Steroselective synthesis of imidazolidin-4-ones from α-amino amides of the antimalarial primaquine and substituted benzaldehydes

Imidazolidin-4-ones are commonly employed as skeletal modifications in bioactive oligopeptides, either as proline surrogates or for protection of the N-terminal amino acid against aminopeptidase-catalysed hydrolysis . We have been working on the synthesis of imidazolidin-4-ones of the antimalarial primaquine , through acylation of primaquine with an α-amino acid and subsequent reaction of the resulting α-aminoamide with a ketone or aldehyde. Thus, when using racemic primaquine, an optically pure chiral α-amino acid and an aldehyde as starting materials, four imidazolidin-4-one diastereomers are to be expected (Scheme 1). However, we have recently observed that imidazolidin-4-one synthesis was stereoselective when 2-carboxybenzaldehyde (2CBA)* was used, as only two diastereomers were produced2. Computational studies have shown that the imine formed prior to ring closure had, for structures derived from 2CBA, a quasi-cyclic rigid structure2. This rigid conformation is stabilized by an intramolecular hydrogen bond involving the C=O oxygen atom of the 2-carboxyl substituent in 2CBA and the N-H group of the α-amino amide moiety2. These findings led us to postulate that the 2-carbonyl substituent in the benzaldehyde moiety was the key for the stereoselective synthesis of the imidazolidin-4-ones2.

Anti-pneumoscystis carinni activitiy of primaquine imidazolidin-4-ones

Pneumocystis pneumonia (PCP) is one of the most frequent causes of mortality among HIV-infected patients. Primaquine (PQ) is an antimalarial 8-aminoquinoline effective against PCP when given in combination with clindamycin. This has drawn the attention of Medicinal Chemists towards the anti-PCP activity of 8-aminoquinolines, not only confined to those exhibiting antimalarial activity [1]. It is thought that anti-PCP 8-aminoquinolines exert their anti-PCP activity by acting on the electronic transport and redox system of the P. carinii pathogen [1]. Recently, our research group has been developing imidazolidin-4-one derivatives of PQ (Scheme 1), targeting novel compounds with improved therapeutic action, namely, higher resistance to metabolic inactivation, lower toxicity and equal or higher antimalarial activity than that of the parent drug [2,3]. These imidazolidin-4-ones were seen to block the transmission of rodent malaria, caused by Plasmodium berghei on BalbC mice, to the mosquito vector Anopheles stephensi [3]. The anti-PCP activity of our PQ derivatives is now under study and preliminary in vitro assays [4] show that some of the compounds exhibit slight to moderate activity after a 72 h incubation period against P. carinii. In one case, the IC50 was comparable to that of parent PQ. Both these studies and forthcoming results from ongoing biological assays will be presented and discussed.

Synthesis of new 1,8-dihydroxy-9h-xanthen-9-ones

XXVth European Colloquium on Heterocyclic Chemistry, Reading, UK, 13 – 17 Agosto de 2012.

Reduction of periodic difference systems to linear or autonomous ones

We extend Floquet theory for reducing nonlinear periodic difference systems to autonomous ones (actually linear) by using normal form theory.

Ones i antenes

Treball de recerca realitzat per un alumne d’ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l’any 2006. L’objectiu final de la recerca consisteix en explicar com s’han construit antenes casolanes per establir connexions a xarxes sense fils (wireless/wifi) i comprovar-ne el funcionament i característiques. Prèviament es revisa teòricament què són les ones, les característiques que tenen i dels tipus d'antenes i la seva relació amb la salut. Posteriorment, en una part pràctica a mode de manual, s’explica com connectar-se a una xarxa sense fils i com construir antenes i comprovar-ne el correcte funcionament.

Física d'ones aplicada a l'estudi d'un ocell

Treball de recerca realitzat per un alumne d’ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l’any 2008. L’objectiu d’aquest treball ha estat l’aplicació pràctica dels mètodes d’anàlisi del so a l’estudi de cants de diversos individus d’una espècie d’ocell, el tallarol de casquet, per arribar al reconeixement tant d’aquesta espècie com dels diferents individus enregistrats. El treball consta de dues parts: una primera part pràctica que inclou la gravació dels cants a la natura, la seva classificació i anàlisi, i una segona del seu estudi a través dels sonogrames aplicant criteris físics i l’extracció de conclusions.