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Using a single calcium ion confined in a surface-electrode trap, we study the interaction of electric quadrupole transitions with a passively phase-stable optical standing wave field sourced by photonics integrated within the trap. We characterize the optical fields through spatial mapping of the Rabi frequencies of both carrier and motional sideband transitions as well as AC Stark shifts. Our measurements demonstrate the ability to engineer favorable combinations of sideband and carrier Rabi frequency as well as AC Stark shifts for specific tasks in quantum state control and metrology., 11 pages, 8 figures

Nel contributo, si ricorda la figura del Professor Angelo Mangini, attivo presso la Facoltà di Chimica Industriale dal 1938 al 1978. In particolare, vengono sottolineati i suoi rapporti con importanti scienziati internazionali nel campo della chimica organica.

Photonics integrated within a planar ion trap are used to generate phase stable optical standing waves, allowing experimental demonstration of position- and transition-dependent qubit excitation. We discuss application to quantum logic and motion control.

The merge of organosilicon and sulfur chemistry herein reported is part of the scientific collaboration developed through several decades between the Bologna and Florence Universities. Besides the generation of new acylsilanes and of unprecedented silylated thiocarbonyl compounds, novel unconventional synthetic methodologies are highlighted based on the use of these compounds. Moreover, the capability of the sulfur to promote thiophilic addition to the thiocarbonyl moieties as well as the ability of the thiolate group to act as a leaving group in the presence of suitable organometallic reagents is briefly reviewed.

The three-component Mannich reaction between in situ generated imines and enolates gives rapid access to diverse beta- and gamma- amino carbonyl compounds. The employment of tailored catalysts and promoters permits control of regio-, chemo-, and stereoselectivity in both direct and indirect variants of the Mannich reaction

The catalytic properties of chitosan aerogel for the direct asymmetric aldol reaction in water assisted by various surfactants and acid co-catalysts have been evaluated by employing a range of donor and acceptor systems. A beneficial effect on both the yields and nantioselectivities was observed, and the combination of surfactants and acid co-catalysts has proven particularly useful in the case of heterocyclic ketone donors.

none 8 The first catalytic asymmetric Pictet–Spengler reaction of isatins is presented. BINOLderived phosphoric acids were found to be competent catalysts for this transformation, giving challenging spirooxindole structures bearing a quaternary stereocentre with generally good results. The 1,2,3,4-tetrahydro-b-carboline products (spiroindolinones) are the core of some newly discovered antimalarial agents. mixed S. Duce; F. Pesciaioli; L. Gramigna; L. Bernardi; A. Mazzanti; A. Ricci; G. Bartoli; G. Bencivenni S. Duce; F. Pesciaioli; L. Gramigna; L. Bernardi; A. Mazzanti; A. Ricci; G. Bartoli; G. Bencivenni

The catalytic asymmetric inverse-electron-demand (IED) [4+2] cycloaddition of various salicylaldehyde-derived N-arylimines with electron-rich alkenes in the presence of chiral BINOL-derived phosphoric acid catalysts has been studied with the aim of obtaining optically active 4-aminobenzopyran derivatives. Dienophiles such as 2,3-dihydro-2H-furan, benzyl N-vinylcarbamate and 2-vinylindole have been employed.

Optically active β-amino-α-methylene carbonyl derivatives (aza-Morita−Baylis−Hillman adducts) were prepared using a one-pot protocol involving an enantioselective Mannich reaction catalyzed by vari...

The different behavior of 3- and 2-vinylindoles in Diels-Alder cycloaddition reactions in the presence of bifunctional hydrogen bond donor organocatalysts is described.

1,3-Dipolar cycloaddition of C-aryl-N-aryl- and C-carboxymethyl-N-aryl-nitrile imines with functionalized acetylenes have been studied. Regioisomeric mixtures have been obtained with the 5-substituted pyrazole as the major cycloadduct. Under scandium triflate catalysis a reversal in the regiochemistry was observed, especially in the case of C-carboxymethyl-N-aryl-nitrile imines.

A simple and efficient organocatalytic enantioselective hydrophosphonylation of imines to enantiomerically enriched alpha-amino phosphonates is reported. By using 10 mol % of quinine as the catalyst in the enantioselective addition of diethyl phosphite to N-Boc protected imines, alpha-amino phosphonates are obtained in moderate to good yields and with up to 94% ee.

New enantiomerically pure 1,3-bis(2’-oxazolinyl)ferrocenes have been synthesized in good yields starting from 1,3-ferrocene dicarboxylic acid. Moreover, the possibility of performing a regioselective lithiation in position 2 of the disubstituted cyclopentadienyl ring of these compounds has been demonstrated.

The cyanobis(dibenzylamino)borane-mediated transformation of chiral aldehydes into the corresponding α-amino nitriles is described. Starting from these compounds short synthetic routes can be envisaged for obtaining diastereomerically pure functionalized 1,2-diamines and hydroxylated α-amino acids that are of interest as core key units of biologically active substances or as potential ligands for asymmetric catalysis. The stereochemical outcome of the aminative cyanation reaction is discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

The synthesis of levetiracetam and its enantiomer by deracemization of (±)-2-bromobutyric acid using either ( S )- or ( R )- N -phenylpantolactam as chiral auxiliaries, followed by S N 2 substitution of the bromine atom by a 2-oxopyrrolidin-1-yl group and amidation of the carboxylic acid, is described.

The synthesis of new 2-sulfanylferrocenylphosphonates and derivatives has been achieved through a P-S to P-C [1,3]-sigmatropic rearrangement. The asymmetric version of this reaction has been successfully performed starting from a ferrocenylphosphorodiamidothioate and afforded, as a single diastereoisomer, enantiomerically pure planar chiral ortho-thio-substituted ferrocenyl phosphorodiamidate.

Several new ligands featuring a rigid three ring skeleton have been prepared for the first time following a modular approach. Chirality has been introduced by use of an oxazoline moiety fused with a cyclopenta[b]thiophene backbone. The efficiency and stereochemical impact of these ligands on the copper-catalyzed enantioselective addition of Et2Zn to chalcone was examined and enantiomeric excesses up to 79% were achieved using the ligand (R,R)-16 substituted with a methyl group at the cyclopenta moiety. Computational and ESI-mass spectral studies show that these new compounds behave as monodentate ligands towards Cu+. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Enantiomerically pure central and planar chiral ferrocenyl cyanohydrins have been used for the synthesis of previously unreported 5-ferrocenyl-oxazolines and a 5-ferrocenyl-thiazoline where the central chirality lies on the carbon bearing the oxygen or the sulfur atom. The epimerization at C 5 of the oxazoline ring has also been investigated.

Enantiopure fluorinated isoxazolidines and amino polyols were obtained from the 1,3-dipolar cycloaddition of allylic fluorides and Z-α-phenyl-N-methylnitrone under environment-friendly conditions.

A synthesis of ferrocenyl-oxazolines is described using an iodide-mediated ring expansion of N-ferrocenoyl-aziridine-2-carboxylic esters. The ring enlargements take place with full stereocontrol, namely net retention of configuration. Modification of the ester function by a Grignard reaction leads to three new types of ferrocenyl-oxazoline carbinol ligands, which were used as chiral ligands in the asymmetric addition of diethylzinc to benzaldehyde (e.e.s ranging from 46 to 62%). The planar chiral ferrocenyl-oxazoline carbinol ligand gave a very good result (e.e. 90%) in the palladium-catalyzed allylic substitution of 1,3-diphenyl prop-2-enylacetate with dimethyl malonate.

The enantioselective synthesis of bicyclic sulfonium salts 8 or 9, thioanalogues of swainsonine derivatives, is described. The synthetic strategy is based on a stereo- and regiospecific transannular cyclization reaction of nine-membered cyclic sulfides, mediated by Me(3)SiI or carried out under acidic catalysis.

Rac-N-substituted pantolactams (5) are readily obtained in medium to good yields by reaction of rac-pantolactone (1) with primary amines under acid catalysis, whether at 250°C in a pressure reactor or under microwave irradiation. It appears that the amine can react with pantolactone at the carbonyl carbon atom to give a hydroxyamide (3) in a reversible way and at the methylene carbon atom to give a γ-amino acid (4). The last one on dehydration would give the corresponding pantolactam (5).

A new protocol is described for the stereocontrolled synthesis of pseudo-C(2)-symmetric core units of interest as candidates for HIV protease inhibition. Addition of unbranched and branched organolithium reagents to cyanohydrins from l-phenylalaninal and l-isoleucinal, followed by in situ reduction of the intermediate imines and CHT deprotection under MW irradiation, led to 1,3-diamino alcohols 6a and 8a as the major products in satisfactory to good yields. The first preparation of a previously unreported pseudo-C(2)-symmetric triamino derivative was accomplished expeditiously via high-yielding nitro-Mannich addition of the silylnitronate, from 2-phenyl-1-nitroethane, to the PMP imine derived from l-phenylalaninal. Reduction of the nitro group in the moderately unstable nitro diamine adduct, followed by chromatographic separation of the required diastereoisomer and CHT debenzylation under MW irradiation, led to the 2-PMP-protected triamine 19 isolated as a bis(sulfonamide).

Starting from inexpensive alcohol sugars we have synthesised a series of oxygen- and nitrogen-containing enantiopure thiepanes to investigate the structural and stereochemical requirements for inhibitory activity against a variety of glycosidases. An interesting trend was observed on analysis of the biological screening results for these derivatives.

The reactions of thioferrocenoylsilanes with organolithium reagents, dienes and reducing agents which afford α-silyl sulphides, dihydrothiopyranes and α-silyl ferrocenyl thiols, respectively, have been investigated. α-Silyl sulphides were further functionalised through carbodesilylation with aldehydes. We also report the synthesis of a new planar chiral thioferrocenoylsilane that gave good diastereomeric excess in the reaction with t-butyllithium, lithium lutidine and 2,3-dimethylbuta-1,3-diene. The 1,1′-bis-thioferrocenoylsilane, too unstable to be isolated, was trapped in situ with dienes.

Ethynyl silyl ketone 1 proved to be a very efficient Michael acceptor in carbocupration and metallocupration reactions. In particular, when using carbocuprates, a smooth entry to polyenals can be obtained, while, when using metallocuprates, silyl- and stannylpropenoyl silanes may be obtained, very powerful intermediates in organic synthesis.

A new 2,3-diamino conduritol, isoster of conduritol F, was obtained starting from d -sorbitol. In the synthetic sequence an unprecedented transannular cyclization led, as a side product, to a bicyclic compound bearing a cyclopropyl ring. The synthesis of the completely deprotected 2,3-diamino conduritol, isoster of conduritol B, was devised via the intermediate O-benzylation of the OH groups. The O-methylated and deprotected 2,3-diamino conduritols were evaluated as inhibitors of α- and β-glucosidase.

Organomanganese halides and organomanganates prepared by transmetalation of organolithium and Grignard reagents add smoothly to the carbonyl moiety of acylsilanes and of substituted aldehydes bearing a chiral center at the a-position affording the desired alcohols in good to excellent yields and with essentially no undesired products from enolization. Comparison of the stereochemical outcome with that observed for other organometallic species, outlines the capability of organomanganese reagents to induce uniformly good diastereoselectivities, in a number of cases significantly higher than reported previously for these reactions. The key role displayed by the R3Si group in promoting high 1,2-asymmetric induction, clearly emerges in the comparison of acylsilane 12 with the corresponding aldehyde 13. The sense of the Cram:anti-Cram selectivity depends upon the nature of the carbonyl reagents engaged in these reactions. © 2001 Elsevier Science B.V. All rights reserved.

The electrophilic amination of carbanions allows the preparation of a wide range of amines through an unconventional C−N bond-forming reaction. The concepts behind the varied synthetic approaches, classified by the nature of the aminating agent and of the organometallic species, are discussed. The mild operational conditions, the high selectivity, and the availability of the starting materials are good assets of these processes which nicely complement each other. New appealing and flexible routes can be devised, leading in several cases to the synthesis of otherwise not easily accessible N-containing compounds.

Highly functionalized arylmagnesium bromides are readily prepared by an iodine–magnesium exchange reaction. In the presence of catalytic amounts of copper(I) salts and chlorotrimethylsilane, they add to various enones leading to the conjugate addition products in 66–89% yield.

We have demonstrated the generality of a simple procedure, synthesizing enantiomerically pure (+)-conduritol B and (−)-conduritol F derivatives, starting from d -mannitol and d -sorbitol, respectively. This method, slightly modified, can also be applied to the synthesis of unprotected conduritols: (−)-conduritol E and (−)-conduritol F were obtained.

Thioacylsilanes containing the ferrocene moiety, easily prepared from the corresponding acylsilanes with Lawesson's reagent at room temperature, can be transformed into vinyl silanes, sulfur heterocycles and sulfines.