bluuebunny/crossref_metadata_2025 huggingface dataset:
A Definitive Synthesis ofD‐myo‐Inositol 1,4,5,6‐Tetrakisphosphate and Its EnantiomerD‐myo‐Inositol 3,4,5,6‐Tetrakisphosphate from a Novel Butane‐2,3‐diacetal‐Protected Inositol
Authors: Mills Stephen J. , Riley Andrew M. , Liu Changsheng , Mahon Mary F. , Potter Barry V. L.
Published: December 2003

New and rapid syntheses of the enantiomeric intracellular signalling moleculesd‐myo‐inositol 1,4,5,6‐tetrakisphosphate (1 a) andD‐myo‐inositol 3,4,5,6‐tetrakisphosphate (1 b) are described. The synthetic strategy employs the novel butane‐2,3‐diacetal‐protected (BDA‐protected)myo‐inositol (±)‐3 ab, directly accessible frommyo‐inositol on a large scale, and an optical resolution with diastereoisomeric (R)‐(−)‐acetylmandelate esters. The X‐ray crystal structure of (±)‐4, an unusual side product of acid‐catalysed reaction ofmyo‐inositol with butanedione is also presented, and the absolute configurations of1 aand1 bare definitively assigned by conversion of key precursors into (+)‐bornesitol andL‐iditol hexaacetate, respectively. Biological activity of synthetic1 bwas confirmed in comparison with the natural polyphosphate.
Total Synthesis and Biological Evaluation of (−)Apicularen A and Analogues Thereof
Authors: Nicolaou K. C. , Kim David W. , Baati Rachid , O′Brate Aurora , Giannakakou Paraskevi
Published: December 2003

Apicularen A (1) and related benzolactone acylenamines belong to a growing class of novel natural products possessing highly cytotoxic properties. The challenging structure of 1 includes a 10‐membered macrolactone ring, a tetrahydropyran system, an o,m‐substituted phenol and a doubly unsaturated acyl group attached on the side chain enamine functionality. The total synthesis of apicularen A described herein involves a strategy equivalent to its proposed biosynthesis and entails a reiterative two‐step procedure featuring allylation and ozonolytic cleavage to grow the molecule's chain by one acetate unit at a time. The developed synthetic technology was applied to the construction of a series of apicularen A analogues whose biological evaluation established a set of structure–activity relationships in this new area of potential importance in cancer chemotherapy.
Synthesis of Conjugated Polyrotaxanes
Authors: Michels Jasper J. , O'Connell Michael J. , Taylor Peter N. , Wilson Joanne S. , Cacialli Franco , Anderson Harry L.
Published: December 2003

A series of conjugated polyrotaxane insulated molecular wires are synthesised by aqueous Suzuki polymerisation, using hydrophobic binding to promote threading of the cyclodextrin units. These polyrotaxanes have conjugated polymer cores based on poly(para‐phenylene), polyfluorene, and poly(diphenylene‐vinylene), threaded through 0.9–1.6 cyclodextrins per repeat unit. Bulky naphthalene‐3,6‐disulfonate endgroups prevent the macrocycles from slipping off the conjugated polymer chains. Dialysis experiments show that the cyclodextrins become unthreaded only if smaller stoppers are used. MALDI TOF mass spectra detect oligomers with up to ten threaded cyclodextrins, and reveal the presence of some defects that result for oxidative homo‐coupling of boronic acids. Weight‐average molecular weights were determined by analytical ultracentrifugation, demonstrating that step‐growth polymerisation is efficient enough to achieve degrees of polymerisation up to ≈20 repeat units (84 para‐phenylenes). The fluorescence spectra of these polyrotaxanes indicate that the presence of the threaded cyclodextrin macrocycles reduces the flexibility of the conjugated polymer π‐systems. Both the solution and the solid‐state photoluminescence quantum yields are enhanced upon threading of the conjugated polyaromatic cores through α‐ or β‐cyclodextrins, and the emission spectra of the polyrotaxanes are blue‐shifted compared to the corresponding unthreaded polymers. The greater weight of the 0–0 transition in the emission spectra, as well as the smaller Stokes shift, indicate that the polyrotaxanes are more rigid than the unthreaded polymers.
Generation and Coupling of [Mn(dmpe)2(CCR)(CC)]. Radicals Producing Redox‐Active C4‐Bridged Rigid‐Rod Complexes
Authors: Fernández Francisco J. , Venkatesan Koushik , Blacque Olivier , Alfonso Montserrat , Schmalle Helmut W. , Berke Heinz
Published: December 2003

The symmetric d5 trans‐bis‐alkynyl complexes [Mn(dmpe)2(CCSiR3)2] (R = Me, 1 a; Et, 1 b; Ph, 1 c) (dmpe = 1,2‐bis(dimethylphosphino)ethane) have been prepared by the reaction of [Mn(dmpe)2Br2] with two equivalents of the corresponding acetylide LiCCSiR3. The reactions of species 1 with [Cp2Fe][PF6] yield the corresponding d4 complexes [Mn(dmpe)2(CCSiR3)2][PF6] (R = Me, 2 a; Et, 2 b; Ph, 2 c). These complexes react with NBu4F (TBAF) at −10 °C to give the desilylated parent acetylide compound [Mn(dmpe)2(CCH)2][PF6] (6), which is stable only in solution at below 0 °C. The asymmetrically substituted trans‐bis‐alkynyl complexes [Mn(dmpe)2(CCSiR3)(CCH)][PF6] (R = Me, 7 a; Et, 7 b) related to 6 have been prepared by the reaction of the vinylidene compounds [Mn(dmpe)2(CCSiR3)(CCH2)] (R = Me, 5 a; Et, 5 b) with two equivalents of [Cp2Fe][PF6] and one equivalent of quinuclidine. The conversion of [Mn(C5H4Me)(dmpe)I] with Me3SiCCSnMe3 and dmpe afforded the trans‐iodide‐alkynyl d5 complex [Mn(dmpe)2(CCSiMe3)I] (9). Complex 9 proved to be unstable with regard to ligand disproportionation reactions and could therefore not be oxidized to a unique MnIII product, which prevented its further use in acetylide coupling reactions. Compounds 2 react at room temperature with one equivalent of TBAF to form the mixed‐valent species [{Mn(dmpe)2(CCH)}2(μ‐C4)][PF6] (11) by C–C coupling of [Mn(dmpe)2(CCH)(CC.)] radicals generated by deprotonation of 6. In a similar way, the mixed‐valent complex [{Mn(dmpe)2(CCSiMe3)}2(μ‐C4)][PF6] [12]+ is obtained by the reaction of 7 a with one equivalent of DBU (1,8‐diazabicyclo[5.4.0]undec‐7‐ene). The relatively long‐lived radical intermediate [Mn(dmpe)2(CCH)(CC.)] could be trapped as the MnI complex [Mn(dmpe)2(CCH)(CCO2)] (14) by addition of an excess of TEMPO (2,2,6,6‐tetramethyl‐1‐piperidinyloxy) to the reaction mixtures of species 2 and TBAF. The neutral dinuclear MnII/MnII compounds [{Mn(dmpe)2(CCR3)}2(μ‐C4)] (R = H, 11; R = SiMe3, 12) are produced by the reduction of [11]+ and [12]+, respectively, with [FeCp(C6Me6)]. [11]+ and [12]+ can also be oxidized with [Cp2Fe][PF6] to produce the dicationic MnIII/MnIII species [{Mn(dmpe)2(CCR3)}2(μ‐C4)][PF6]2 (R = H, [11]2+; R = SiMe3, [12]2+). Both redox processes are fully reversible. The dinuclear compounds have been characterized by NMR, IR, UV/Vis, and Raman spectroscopies, CV, and magnetic susceptibilities, as well as elemental analyses. X‐ray diffraction studies have been performed on complexes 4 b, 7 b, 9, [12]+, [12]2+, and 14.
Selection and Amplification of Mixed‐Metal Porphyrin Cages from Dynamic Combinatorial Libraries
Authors: Stulz Eugen , Scott Sonya M. , Bond Andrew D. , Teat Simon J. , Sanders Jeremy K. M.
Published: December 2003

Mixed metallo–porphyrin cages were selected and amplified from dynamic combinatorial libraries (DCLs) by using appropriate templates. The cages are composed of two bisphosphine substituted zinc(II) porphyrins as ligand donors and two rhodium(III) or ruthenium(II) porphyrins as ligand acceptors, and are connected through metal–phosphorus coordination. Ru and Rh porphyrins that display a large structural diversity were employed. The templating was achieved by using 4,4′‐bpy, 3,3′‐dimethyl‐4,4′‐bipyridine and benzo[lmn]‐3,8‐phenanthroline, and acts through zinc–nitrogen coordination. The absolute amount of amplification from the DCLs is strongly dependent on the combination of the Ru/Rh porphyrin and the template; cages with sterically demanding porphyrins can only form with smaller templates. In the case of tert‐butyl‐substituted TPP (TPP=tetraphenylporphyrin), cages are not formed at all. The formation of the cages is usually complete within 24 h at an ambient temperature; in the case of the cage containing RhIIIOEP (OEP=octaethylporphyrin) and bpy, the pseudo‐first‐order rate constant of cage formation was determined to be 2.1±0.1×10−4 s−1 (CDCl3, 25 °C). Alternatively, heating the mixtures to 65 °C and cooling to room temperature yields the cages within minutes. The 1H NMR chemical shifts of several characteristic protons show large differences upon changing the identity of the Ru/Rh porphyrin and the central metal; this is most likely to arise from variations in the geometry of the cages. The X‐ray crystal structure of a cage, which contains RhIIIOEP as a porphyrin acceptor and bpy as template, demonstrates that the cages can adopt severely distorted conformations to accommodate the relatively short templates. An extension to mixed DCLs showed that only limited selectivity is displayed by the various templates. Formation of mixed cages that contain two different rhodium porphyrins prevents effective selection, although the kinetic lability of the systems allows for some amplification. This lability, however, also prevents isolation of the individual cages. Removal of the template leads to re‐equilibration, thus the templates act as scaffolds to keep the structures intact.
Oligosaccharide–Peptide Ligation of Glycosyl Thiolates with Dehydropeptides: Synthesis of S‐Linked Mucin‐Related Glycopeptide Conjugates
Authors: Galonić Danica P. , van der Donk Wilfred A. , Gin David Y.
Published: December 2003

A chemoselective strategy for oligosaccharide–peptide ligation is described in which α‐thio analogues of mucin‐related glycoconjugates can be readily accessed through site‐selective conjugate addition of complex oligosaccharide thiolates to dehydroalanine‐containing peptides. The efficiency of the ligation is highlighted by the rapid convergent assembly of thio‐isosteres of the four tumor‐associated carbohydrate antigens, TN, T, STN, and 2,6‐ST, as a pair of diastereoisomers at the newly formed cysteine stereocenter. The process proceeds in high yield and with complete retention of the α‐anomeric configuration.
The First Catalytic Highly Enantioselective Alkylation of Ketimines—A Novel Approach to Optically Active Quaternary α‐Amino Acids
Authors: Saaby Steen , Nakama Kimitaka , Lie Mette Alstrup , Hazell Rita G. , Jørgensen Karl Anker
Published: December 2003

A series of novel ketimines with intrinsic protecting group anchoring was synthesized and allowed to react with various silylketene acetals in the presence of 5–10 mol % of a chiral Zn(OTf)2‐(R,R)‐Ph‐pybox‐aqua complex. The corresponding optically active quaternary α‐amino acid derivatives were obtained in high yields and with enantioselectivities ranging from 34 % up to 95 % ee. The catalyst was studied by 1H NMR spectroscopy and X‐ray crystallography, and a dynamic equilibrium of two species was identified in solution. These are a homo‐chiral 1:2 metal–ligand complex and a 1:1 metal–ligand complex, of which the latter is expected to be the actual catalyst of the diastereo‐ and enantioselective reaction. A strong positive nonlinear effect was observed due to the formation of a catalytically inactive 1:2 metal–ligand hetero‐chiral complex. On the basis of DFT calculations and the absolute stereochemistry of the products, simultaneous coordination of the imino electrophile and a single molecule of H2O to the chiral Lewis acid complex is proposed. Coordination of the imine‐nitrogen atom in the axial position of an octahedral complex can account for the facial selectivity as well as the diastereoselectivity observed.
The (2‐Phenyl‐2‐trimethylsilyl)ethyl‐(PTMSEL)‐Linker in the Synthesis of Glycopeptide Partial Structures of Complex Cell Surface Glycoproteins
Authors: Wagner Michael , Dziadek Sebastian , Kunz Horst
Published: December 2003

The (2‐phenyl‐2‐trimethylsilyl)ethyl‐(PTMSEL) linker represents a novel fluoride‐sensitive anchor for the solid‐phase synthesis of protected peptides and glycopeptides. Its cleavage is achieved under almost neutral conditions using tetrabutylammonium fluoride trihydrate in dichloromethane thus allowing the construction of complex molecules sensitive to basic and acidic media commonly required for the cleavage of standard linker systems. The advantages of the PTMSEL linker are demonstrated in the synthesis of glycopeptides from the liver intestine (LI)‐cadherin and the mucin MUC1, bearing carbohydrate moieties such as N‐linked chitobiose or O‐linked sialyl‐TN‐residues. The synthesis of these types of glycopeptides is difficult because they are prone to secondary structure formation during the synthesis on the solid phase as well as in the completely deprotected form. Using the PTMSEL linker these molecules are accessible by automated synthesis according to the Fmoc strategy without frequently observed side reactions such as aspartimide or diketopiperazine formation.
Structural Basis for Vapoluminescent Organoplatinum Materials Derived from Noncovalent Interactions as Recognition Components
Authors: Lu Wei , Chan Michael C. W. , Zhu Nianyong , Che Chi‐Ming , He Zhike , Wong Kwok‐Yin
Published: December 2003

The spectroscopic properties and crystal structures of a series of platinum(II) complexes bearing functionalized σ‐alkynyl groups, namely [(tBu2bpy)Pt(CCAr)2] (tBu2bpy = 4,4′‐bis‐tert‐butyl‐2,2′‐bipyridine, Ar = 4‐pyridyl, 1; 3‐pyridyl, 2; 2‐pyridyl, 3; 4‐ethynylpyridyl, 4; 2‐thienyl, 5; pentafluorophenyl, 6) have been studied. Solid‐state emissions of 1 and 6 are dependent on their crystallinity. Reversible and selective vapoluminescence was observed for 1 and 6 in the presence of chlorocarbon vapors. For solid 1, dramatic enhancement of green luminescence is observed upon sorption of CH2Cl2 or CHCl3 vapor. The excimeric orange emission for solid 6 is switched to monomeric green emission upon exposure to CH2Cl2 vapor. The luminescent responses of a thin film of 1 towards various organic vapors have also been examined. In the crystallographically determined structure of 1⋅CH2Cl2, the bis(acetylide) moiety acts as the receptor berth for a CH2Cl2 molecule through concerted CH⋅⋅⋅π(CC) interactions, while Cl⋅⋅⋅Cl interactions connect the CH2Cl2 molecules into infinite linear chains. The observed crystal lattices are arranged into scaffolds of varying porosity by weak CH⋅⋅⋅N(py) (1⋅CH2Cl2, 1⋅CH3CN, 4⋅DMF) and CH⋅⋅⋅FC (6, 6⋅CH3CN) interactions. The correlation between the crystal structures of 1⋅CH2Cl2, 1⋅CH3CN, 2, 4⋅DMF, 5, 6, and 6⋅CH3CN and their vapoluminescence suggests that weak nonconventional hydrogen‐bonding interactions preside over the reversible sensing and signalling processes.
Solvothermal Syntheses of High‐Nuclearity Vanadium(III) Clusters
Authors: Laye Rebecca H. , Murrie Mark , Ochsenbein Stefan , Bell Aidan R. , Teat Simon J. , Raftery James , Güdel Hans‐Ulrich , McInnes Eric J. L.
Published: December 2003

Superheating alcohol solutions of simple trimetallic vanadium(III) precursors gives the octa‐ and decametallic vanadium(III) clusters [V8(OEt)8(OH)4(O2CPh)12] (1) and [V10(OMe)20(O2CMe)10] (2). Cluster 2 is the largest vanadium(III) cluster synthesised to date. Thus solvothermal synthetic techniques are an excellent route to high‐nuclearity vanadium(III) clusters. Both 1 and 2 consist of a planar or near‐planar array of VIII ions. The metal ions in 1 are bridged by either a μ2‐hydroxide and two μ2‐benzoate groups or two μ2‐ethoxides and a μ2‐benzoate groups, the two bridging arrangements alternating around the ring. In 2 each pair of neighbouring metal ions is bridged by two μ2‐methoxides and a μ2‐acetate, and this molecule is the VIII analogue of Lippard's famous “ferric wheel”. Preliminary magnetic susceptibility studies show the exchange coupling in both complexes to be antiferromagnetic in nature, with the coupling stronger in 1 than in 2.
Mouse strain‐specific nicotinic acetylcholine receptor expression by inhibitory interneurons and astrocytes in the dorsal hippocampus
Authors: Gahring Lorise C. , Persiyanov Karina , Dunn Diane , Weiss Robert , Meyer Erin L. , Rogers Scott W.
Published: December 2003

The response by individuals to nicotine is likely to reflect the interaction of this compound with target nAChRs. However, resolving how different genetic backgrounds contribute to unique mouse strain‐specific responses to this compound remains an important and unresolved issue. To examine this question in detail, expression of the nicotine acetylcholine receptor (nAChR) subunits α3, α4, α5, α7, β2, and β4 was measured in the dorsal hippocampus using immunohistochemistry in mouse strains or lines BALB/c, C3H/J, C57BL/6, CBA/J, DBA/2, Long Sleep (LS), Short Sleep (SS), and CF1. The nAChRs in all mice colocalized with glutamic acid decarboxylase (GAD)‐positive interneurons that were subclassified into at least four groups based on nAChR subunit heterogeneity. A notable difference between mouse strains was the expression of nAChRs by astrocyte subpopulations in CA1 subregions whose numbers vary inversely with nAChR‐immunostained neurons. This novel relationship also correlated with published parameters of strain sensitivity to nicotine. Attempts to identify the origin of this significant difference in nAChR expression among strains included comparison of the entire nAChRα4 gene sequence. Although multiple polymorphisms were identified, including two that changed nAChRα4 amino acid coding, none of these clearly correlate with strain‐related differences in cell type‐specific nAChR expression. These findings suggest that mouse strain‐specific behavioral and physiological responses to nicotine are likely to be a reflection of a complex interplay between genetic factors that shape differences in expression and cellular architecture of this modulatory neurotransmitter system in the mammalian nervous system. J. Comp. Neurol. 468:334–346, 2004. © 2003 Wiley‐Liss, Inc.
Morphologic characterization of rat taste receptor cells that express components of the phospholipase C signaling pathway
Authors: Clapp Tod R. , Yang Ruibiao , Stoick Cristi L. , Kinnamon Sue C. , Kinnamon John C.
Published: December 2003

Rat taste buds contain three morphologically distinct cell types that are candidates for taste transduction. The physiologic roles of these cells are, however, not clear. Inositol 1,4,5‐triphosphate (IP3) has been implicated as an important second messenger in bitter, sweet, and umami taste transductions. Previously, we identified the type III IP3 receptor (IP3R3) as the dominant isoform in taste receptor cells. In addition, a recent study showed that phospholipase Cβ2 (PLCβ2) is essential for the transduction of bitter, sweet, and umami stimuli. IP3R3 and PLCβ2 are expressed in the same subset of cells. To identify the taste cell types that express proteins involved in PLC signal transduction, we used 3,3′diaminobenzidine tetrahydrochloride immunoelectron microscopy and fluorescence microscopy to identify cells with IP3R3. Confocal microscopy was used to compare IP3R3 or PLCβ2 immunoreactivity with that of some known cell type markers such as serotonin, protein gene‐regulated product 9.5, and neural cell adhesion molecule. Here we show that a large subset of type II cells and a small subset of type III cells display IP3R3 immunoreactivity within their cytoplasm. These data suggest that type II cells are the principal transducers of bitter, sweet, and umami taste transduction. However, we did not observe synapses between type II taste cells and nerve fibers. Interestingly, we observed subsurface cisternae of smooth endoplasmic reticulum at the close appositions between the plasma membrane of type II taste cells and nerve processes. We speculate that some type II cells may communicate to the nervous system via subsurface cisternae of smooth endoplasmic reticulum in lieu of conventional synapses. J. Comp. Neurol. 468:311–321, 2004. © 2003 Wiley‐Liss, Inc.
Definition and connections of the entopallium in the zebra finch (Taeniopygia guttata)
Authors: Krützfeldt Nils O.E. , Wild J. Martin
Published: December 2003

In birds the entopallium (formerly known as the core region of ectostriatum) is the major thalamorecipient zone, within the telencephalon, of the tectofugal visual system. Here we sought to redefine the entopallium in the zebra finch, particularly with respect to a laterally adjacent zone, known as the perientopallium (formerly known as the periectostriatal belt), and to determine its projections. We show that the entopallium can be defined by the almost complete overlap of dense terminations of thalamic rotundal afferents and intense cytochrome oxidase activity and parvalbumin immunoreactivity. The perientopallium, on the other hand, can be defined by relatively sparse projections from nucleus rotundus, a calretinin‐positive plexus of nerve fibers, and weak cytochrome oxidase activity and parvalbumin immunoreactivity. Within the entopallium, medial and lateral parts can be distinguished on the basis of cell packing density, differential patterns of parvalbumin immunoreactivity and cytochrome oxidase activity, and different projections. We show that the entopallium projects laterally and diffusely to the perientopallium and nidopallium (formerly the neostriatum) and specifically and densely to a teardrop‐shaped nucleus in the ventrolateral mesopallium (formerly known as the hyperstriatum ventrale), here called MVL (abbreviation used as a proper name). This latter projection arises predominantly from medial parts of the entopallium, which also receives a reciprocal projection from MVL, and projects to the lateral striatum. These findings suggest that the entopallium can be divided into medial and lateral parts having different functions, one of which is to provide for an extratelencephalic outflow from the medial part, via the lateral striatum. The findings also challenge the idea that informational flow through the various stations of the telencephalic tectofugal visual system is largely sequential and, together with findings in the chicken (Alpar and Tömböl [2000] Ann Anat 182:101–110), suggest instead that further substantial projections to telencephalic visual areas in birds can arise independently from both E (entopallium) and Ep (perientopallial belt). J. Comp. Neurol. 468:452–465, 2004. © 2003 Wiley‐Liss, Inc.
Rostral agranular insular cortex and pain areas of the central nervous system: A tract‐tracing study in the rat
Authors: Jasmin Luc , Granato Alberto , Ohara Peter T.
Published: December 2003

The rostral agranular insular cortex (RAIC) has recently been identified as a site where local changes in GABA and dopamine levels, or application of opioids, can alter nociceptive thresholds in awake animals (Jasmin et al. [2003] Nature 424:316–320). The connections of the cortex dorsal to the rhinal fissure that includes the RAIC have been examined previously, with emphasis on visceral and gustatory functions but not nociception. Here we examined the afferent and efferent connections of the RAIC with sites implicated in nociceptive processing. Sensory information from the thalamus reaches the RAIC via the submedius and central lateral nuclei and the parvicellular part of the ventral posterior nucleus. The RAIC has extensive reciprocal cortico‐cortical connections with the orbital, infralimbic, and anterior cingulate cortices and with the contralateral RAIC. The amygdala, particularly the basal complex, and the nucleus accumbens are important targets of RAIC efferent fibers. Other connections include projections to lateral hypothalamus, dorsal raphe, periaqueductal gray matter, pericerulear region, rostroventral medulla, and parabrachial nuclei. The connectivity of the RAIC suggests it is involved in multiple aspects of pain behavior. Projections to the RAIC from medial thalamic nuclei are associated with motivational/affective components of pain. RAIC projections to mesolimbic/mesocortical ventral forebrain circuits are likely to participate in the sensorimotor integration of nociceptive processing, while its brainstem projections are most likely to contribute to descending pain inhibitory control. J. Comp. Neurol. 468:425–440, 2004. © 2003 Wiley‐Liss, Inc.
Regional and subcellular compartmentation of the dopamine transporter and tyrosine hydroxylase in the rat ventral pallidum
Authors: Mengual Elisa , Pickel Virginia M.
Published: December 2003

The ventral pallidum (VP) is a major intermediary in the prefrontal cortical circuitry regulating sensorimotor gating and locomotor behavior, both of which are potently modulated by catecholamines. The VP catecholaminergic innervation is derived from midbrain dopaminergic neurons that differ in expression levels of the dopamine transporter (DAT) and from brainstem noradrenergic neurons without DAT. The preferentially low level of DAT in dopaminergic terminals in the prefrontal cortex and in striatal regions projecting more extensively to the VP medial (VPm) compared with VP lateral (VPl) compartment suggests possible region‐specific differences in VP axonal distribution of DAT. To test this hypothesis, we examined the electron microscopic localization of DAT and the catecholamine‐synthesizing enzyme, tyrosine hydroxylase (TH), in the VPm and VPl of rat brain. In both regions, DAT and TH were localized primarily in small unmyelinated axons and morphologically heterogeneous axon terminals. DAT‐immunogold particles were few in number, but mostly located on the plasma membrane. In contrast, TH immunoreactivity was distributed in the cytoplasm of individual profiles, many of which were without detectable DAT. In comparison with TH, the mean area density of DAT‐labeled axons was low throughout the VP. The mean area density of DAT‐immunogold axon terminals, however, was significantly higher in VPl than in VPm, whereas that of TH‐labeled axons was higher in VPm than in VPl. This dissociation suggests that, compared to the VPl, the VPm receives the greatest input from catecholaminergic afferents that are either nondopaminergic or characterized by having low levels or less terminal distributions of DAT. J. Comp. Neurol. 468:395–409, 2004. © 2003 Wiley‐Liss, Inc.
Connection from the dorsal column nuclei to the superior colliculus in the rat: Topographical organization and somatotopic specific plasticity in response to neonatal enucleation
Authors: García Del Caño Gontzal , Uria Iñigo , Gerrikagoitia Inmaculada , Martínez‐Millán Luis
Published: December 2003

Somatosensory stimuli from the body to deep and intermediate strata of the superior colliculus (SC) are relayed from the dorsal column nuclei (DCN), gracile (GrN) and cuneate (CuN). Electrophysiological studies have shown that the somatosensory representation in SC is arranged into a map‐like pattern. However, there is a lack of studies confirming a morphological correlate of such an organization. On the other hand, after neonatal enucleation in rodents, somatosensory inputs ascend from their normal termination territory in intermediate and deep collicular strata to invade the more dorsally located visual strata. However, the origin of these reactive afferents has not been specified. By using anterograde (biotinylated dextran amine 10,000; BDA) and retrograde (Fluoro‐Gold; FG) tracers, we studied separately the connection from GrN and CuN to the intact and neonatally deafferented SC. GrN‐collicular afferents were found to terminate mainly within the periphery of the caudomedial SC quadrant, whereas CuN‐collicular fibers innervated primarily the lateral part of the rostrolateral and caudolateral collicular quadrants, in a way consistent with previously described functional data. Retrograde tracing experiments using FG injected in SC confirmed this topographical arrangement. Injections of BDA in GrN or CuN of neonatally enucleated rats showed that reactive fibers reaching superficial strata are only those CuN‐collicular fibers innervating the caudolateral SC quadrant, where the forelimb is represented. The present results provide an anatomical substrate for the known somatotopic organization of tactile representation in SC and further reinforce the previous proposal that the plastic reorganization of DCN‐collicular afferents following neonatal enucleation constitutes a functional compensatory response. J. Comp. Neurol. 468:410–424, 2004. © 2003 Wiley‐Liss, Inc.
Expression of vesicular glutamate transporters in rat lumbar spinal cord, with a note on dorsal root ganglia
Authors: Landry Marc , Bouali‐Benazzouz Rabia , El Mestikawy Salah , Ravassard Philippe , Nagy Frédéric
Published: December 2003

Three vesicular glutamate transporters (VGLUTs) have been recently identified and their distribution has been mapped in various brain areas. In the present study, we used morphological approaches to investigate their expression in the rat lumbar spinal cord and dorsal root ganglia. Our results show a complementary distribution of VGLUT‐expressing fibers in the spinal cord, with no overlapping in nerve endings. In the dorsal horn, VGLUT1 is most abundant in mechanosensory/proprioceptive deep afferent fibers. VGLUT2 and VGLUT3 are expressed only at moderate levels in primary sensory afferent fibers and are not used by central projections of nociceptive neurons. VGLUT1 and VGLUT2 mRNAs are mainly segregated in superficial laminae but colocalized in deeper laminae. Weak expression of VGLUT3 mRNA is only detected in deep laminae. The colocalization of VGLUT1 and VGLUT2 transcripts in most sensory neurons of the dorsal root ganglia is not in agreement with the clear segregation between the proteins in their spinal projections. Such a discrepancy suggests targeting mechanisms specific for each transporter and/or a distinct regulation of their translation. In the ventral horn, the expression of VGLUT1 and VGLUT2 mRNAs in motoneuron perikarya suggests the possible unexpected role of glutamate in the vertebrate neuromuscular junction. These results demonstrate the existence of different subpopulations of glutamate nerve terminals in the rat lumbar spinal cord and suggest that functionally distinct subsets of excitatory glutamatergic neuronal networks are involved in sensory processing and motor control. J. Comp. Neurol. 468:380–394, 2004. © 2003 Wiley‐Liss, Inc.
Organization of suprachiasmatic nucleus projections in Syrian hamsters (Mesocricetus auratus): An anterograde and retrograde analysis
Authors: Kriegsfeld Lance J. , Leak Rehana K. , Yackulic Charles B. , LeSauter Joseph , Silver Rae
Published: December 2003

Circadian rhythms in physiology and behavior are controlled by pacemaker cells located in the suprachiasmatic nucleus (SCN) of the hypothalamus. The mammalian SCN can be classified into two subdivisions (core and shell) based on the organization of neuroactive substances, inputs, and outputs. Recent studies in our laboratory indicate that these subdivisions are associated with functional specialization in Syrian hamsters. The core region, marked by calbindin‐D28K (CalB)‐containing cells, expresses light‐induced, but not rhythmic, clock genes. In the shell compartment, marked by vasopressinergic cells and fibers, clock gene expression is rhythmic. Given these findings, an important question is how photic and rhythmic information are integrated and communicated from each of these regions to effector areas. The present study used localized, intra‐SCN iontophoretic injections of the anterograde tracer biotinylated dextran amine (BDA) to investigate intra‐SCN connectivity and the neural pathways by which information is communicated from SCN subregions to targets. Intra‐SCN connections project from the core to the shell compartment of the SCN, but not from the shell to the CalB region of the SCN. Retrograde tracing experiments were performed using cholera toxin‐β (CTB) to determine more specifically whether SCN efferents originated in the core or shell using neurochemical markers for the rhythmic (vasopressin) and light‐induced (CalB) SCN subregions. The combined results from anterograde and retrograde experiments suggest that all SCN targets receive information from both the light‐induced and rhythmic regions of the SCN (albeit to varying degrees) and indicate that light and rhythmic information may be integrated both within the SCN and at target effector areas. J. Comp. Neurol. 468:361–379, 2004. © 2003 Wiley‐Liss, Inc.
Colour in folklore and tradition—The principles
Authors: Hutchings John
Published: December 2003

Human beings use colour to manipulate their personal appearance and environment. A large part of this usage falls within the area of oral tradition and ritual that have been handed down within families, tribes or geographical areas. The resulting images are part of our culture; they are activities that give us feelings of belonging and of doing the ‘right thing’. Two surveys were designed to learn more of these very human activities. The first centered on Britain and Ireland; the other was international. Three major driving forces were found for the use of colour in folklore and symbolism—economic, historical and social. The Principle of Adaptation of Physical Resources accounts for the choice of mourning colours of most countries. Colour usage in death echoes the three approaches to mourning of sadness, joy (for the life of the dead), and fear of the spirits of the dead. The Principle of Adaptation of Ideas accounts for regional variations in colour folklore. This embodies a Darwinian‐type principle of behavior, that is, “to survive within a community a belief must have relevance to that community.” A major principle of folk medicine involving colour is the Principle of curing like with like. There are four Principles of Colour Selection in folklore—by the contrast displayed, as a transfer from the perceived or actual usefulness of the colour, by association, and by availability. Green above all colours has especial significance both in the UK and Ireland. In everyday language it is the Principle of Singularity that controls use of colour words as symbols. The biological mechanism permitting these many and contrasting uses of colour depends on the fact that colour is a perception, not the property of an object. That is, a colour can ‘mean’ whatever we wish it to ‘mean’. © 2003 Wiley Periodicals, Inc. Col Res Appl, 29, 57–66, 2004; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/col.10212
Effects of hue, saturation, and brightness: Part 2: Attention
Authors: Camgöz Nilgün , Yener Cengiz , Güvenç Dilek
Published: December 2003

This is the second part of an experiment by Camgöz, Yener and Güvenç, which investigates attention responses for foreground‐background colour relationships. One hundred and twenty three university undergraduates in Ankara, Turkey, viewed eight background colours selected from HSB colour space, on which colour squares of differing hues, saturations, and brightness's were presented. Participants were asked to show the colour square attracting the most attention on the presented background colour. Findings showed that on any background colour, colours of maximum saturation and brightness attract the most attention (67%). The yellow‐green, green, and cyan range attracts the most attention (45%), followed by the red and magenta range (30%). Foreground‐background colour relationships in terms of attention are also included in the findings of the study. © 2003 Wiley Periodicals, Inc. Col Res Appl, 29, 20–28, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10214
Mechanisms of the Aerobic Oxidation of Alcohols to Aldehydes and Ketones, Catalysed under Mild Conditions by Persistent and Non‐Persistent Nitroxyl Radicals and Transition Metal Salts − Polar, Enthalpic, and Captodative Effects
Authors: Minisci Francesco , Recupero Francesco , Cecchetto Andrea , Gambarotti Cristian , Punta Carlo , Faletti Roberta , Paganelli Roberto , Pedulli Gian Franco
Published: December 2003

The oxidation of alcohols to aldehydes and ketones by air or oxygen under mild conditions (room temperature and atmospheric pressure), catalysed by persistent and non‐persistent nitroxyl radicals in combination with transition metal salts, appears to be the most convenient of the numerous processes developed for these purposes. The thermochemistry, the kinetics, and the Hammett correlations have allowed us to establish, on a quantitative basis, the fundamental difference between the oxidation catalysed by persistent and non‐persistent nitroxyl catalysts. In the latter case, an interesting significant captodative effect is displayed for the first time for the oxidation of substituted benzyl alcohols; the importance of enthalpic and polar effects is emphasised. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A Hetero‐Diels−Alder Approach to Phosphonothiashikimic Acid and New Thiaglycosides
Authors: Heras Montserrat , Gulea Mihaela , Masson Serge , Philouze Christian
Published: December 2003

Phosphonodithioformates undergo hetero‐Diels−Alder cycloadditions with a variety of dienes. In some cases, Lewis acid catalysts were used to control the rate and selectivity of the reactions. Selective radical desulfanylation and subsequent dihydroxylation of the cycloadducts allowed the syntheses of new thiapyran derivatives and, in particular, a phosphono and thio analogue of shikimic acid. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Asymmetric Cyanosilylation of Ketones Catalyzed by Bifunctional Chiral N‐Oxide Titanium Complex Catalysts
Authors: Shen Yongcun , Feng Xiaoming , Li Yan , Zhang Guolin , Jiang Yaozhong
Published: December 2003

A new bifunctional catalytic system based on chiral N‐oxide titanium complexes has been used for the asymmetric cyanosilylation of ketones. Screening of a variety of chiral N‐oxide metal complexes resulted in (1R,2S)‐1‐(2′‐pyridylmethyl)‐2‐(diphenylhydroxymethyl)pyrrolidine N‐oxide titanium complex, which gave O‐TMS cyanohydrins in good yields with enantiomeric excesses of up to 69 %. A catalytic cycle based on experimental phenomena and studies was proposed to explain the origin of the asymmetric induction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A Comparison of Transition States During H‐Atom Abstraction of Monophenols and Catechol by Methyl Radical
Authors: Sun You‐Min , Liu Cheng‐Bu
Published: December 2003

To compare the transition states of para‐substituted phenols with that of catechol, we employed the B3LYP/6−311+G(d,p) method to calculate the energy profiles, the geometries, the spin density distributions, and other physico‐chemical parameters. A comparison between catechol and para‐substituted phenols indicates that their transition state geometries for hydrogen atom abstraction are similar. Substituent effects on the transition states of o‐substituted phenols may differ from those of p‐substituted ones. The calculated value of Ea for catechol is much lower than that of phenol, which arises mainly from the electron‐donating property of the ortho‐hydroxyl group. Although, the intramolecular hydrogen bond (IHB) effect on Ea is small, the IHB effect on the transition state geometry is fairly strong. According to the regression equation of the relative O−H bond dissociation enthalpy (BDE) versus values of Ea for p‐substituted monophenols, the relative O−H BDE of catechol is −8.28 kcal mol−1, which is in agreement with the value obtained through a kinetic analysis (−7.2 kcal mol−1). The values of Ea are governed by resonance effects, which is similar to the observation found for the O−H BDEs. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Total Synthesis of Premithramycinone H and Related Anthrapyran Antibiotics
Authors: Krohn Karsten , Vitz Jürgen
Published: December 2003

Two approaches are described for the preparation of 2‐(1′,3′‐dioxoalkyl)‐substituted 1‐hydroxyanthraquinones10a−dand20a−c, which were cyclized in a biomimetic‐type reaction to the anthra[1,2‐b]pyran skeletons11a−dand21a−cof the heydamycin‐ or pluramycin‐type antibiotics. Cleavage of the methyl ethers afforded the natural product premithramycinone H (2). The simple derivative11bshowed inhibition of the A431 cell line in µmolar concentrations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Efficient Access to Alanine Derivatives by 1,4‐Additions of Potassium Trifluoro(organo)borates
Authors: Navarre Laure , Darses Sylvain , Genet Jean‐Pierre
Published: December 2003

Potassium trifluoro(organo)borates, highly stable and easily prepared organoboron derivatives, were able to react with a great variety of dehydroamino esters. This reaction, catalyzed by rhodium complexes, allowed the formation of alanine derivatives bearing a great variety of amino protecting groups in good to high yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Aromatic Oligoamide Foldamers
Authors: Huc Ivan
Published: December 2003

Aromatic oligoamide foldamers possess a high potential for mimicking the secondary structures of biopolymers. These oligomers are efficiently designed, easy to synthesize, and allow one to reach a wide range of stable folded states. The aryl−amide bond rotation can be restricted through specific attractive and repulsive interactions between the amide and the other functional groups at the ortho position on the aryl moiety. The overall conformation of an oligomer results from the simple linear combination of the local conformational preferences at each amide bond. Thus, the curvature of the oligomeric strand may be tuned from strictly linear to highly bent, giving rise to helices of controllable diameter and extended linear conformations. Conformational rearrangements such as helical−linear strand transitions may be induced upon changing the local conformational preference of aryl−amide bonds. These oligomers also aggregate in various ways, such as stacks of discs, face‐to‐face hydrogen‐bonded linear dimers, or entwined double helices. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
An Improved Access to 4‐Trifluoromethyl‐2(1H)‐quinolinones: The “Watering Protocol”
Authors: Marull Marc , Lefebvre Olivier , Schlosser Manfred
Published: December 2003

Condensation of anilines with ethyl 4,4,4‐trifluoroacetoacetate (7) to afford the corresponding 4,4,4‐trifluoro‐3‐oxobutaneanilides (10), precursors to 4‐(trifluoromethyl)‐2‐quinolinones (11), can be favored and the competing condensation to produce the ethyl 4,4,4‐trifluoro‐3‐(phenylimino)butanoate, the precursor to 2‐(trifluoromethyl)‐4‐quinolinones, avoided if water is occasionally added to the reaction mixture while ethanol is continuously removed by distillation. The anilides 10 also form selectively when 4,4,4‐trifluoroacetoacetyl chloride (6) is allowed to react with anilines. The cyclization of the anilides has to be accomplished under carefully controlled conditions. The resulting 4‐(trifluoromethyl)‐2‐quinolinones (11) can be converted into 4‐(trifluoromethyl)quinolines (13), 4‐(trifluoromethyl)‐2‐quinolinecarboxylic acids (14), and 2‐bromo‐4‐(trifluoromethyl)quinolines (12), the last of which may in turn be converted into 2‐bromo‐4‐(trifluoromethyl)‐3‐quinolinecarboxylic acids (15) and eventually 4‐trifluoromethyl‐3‐quinolinecarboxylic acids (16). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
High π‐Facial Selectivity Through Chelation of Magnesium Ions in the DMD Epoxidation of α,β‐Unsaturated Imides with Chiral Pyrrolidinone Auxiliaries
Authors: Adam Waldemar , Zhang Aimin
Published: December 2003

High diastereoselectivity, but of the opposite sense, is observed in the epoxidation (DMD or mCPBA) of α,β‐unsaturated imides equipped with pyrrolidinone‐type chiral auxiliaries that bear either a hydroxymethyl or trityloxymethyl side chain. This unprecedented reversed π‐facial differentiation is promoted by chelation of a magnesium ion, which results in conformational control over the essential steric interactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Stereochemical Aspects of Enantiopure and Racemic Organolithium Aggregates Li4Ar4 {Ar = C6H4[CH(Me)NMe2]‐2}
Authors: Kronenburg Claudia M. P. , Rijnberg Evelien , Jastrzebski Johann T. B. H. , Kooijman Huub , Spek Anthony L. , van Koten Gerard
Published: December 2003

The compounds (R)‐ and rac‐[1‐(dimethylamino)ethyl]benzene, (R)‐1 and rac‐1, respectively, react quantitatively with tBuLi in a 1:1 molar ratio in pentane to give the corresponding (R)‐ and rac‐[Li4{C6H4[CH(Me)NMe2]‐2}4], (R)‐2 and rac‐2, respectively. The same reaction with nBuLi afforded a 1:1:1 aggregate of nBuLi, 2, and 1 according to the results of quench experiments with H2O and D2O. The 1H, 13C, and 7Li NMR spectra, as well as the single‐crystal X‐ray structure, reveal that (R)‐2 has a unique self‐assembled tetranuclear structure of two diastereoisomeric dimeric units both in solution, in non‐coordinating hydrocarbon solvents, and in the solid state. Detailed information about rac‐2, which, in contrast to the high solubility of (R)‐2, is essentially insoluble in hydrocarbon solvents, was provided by 13C CP/MAS NMR spectra. We conclude that rac‐2 is a self‐assembled tetranuclear aggregate comprising a combination of two dimeric units, but in this case they are derived from the (R)‐ and (S)‐enantiomers, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Conjugated and Cross‐Conjugated π‐Extended Cycloproparenes with Dithiole and Cyclopentadiene Functionality
Authors: Halton Brian , Jones Carissa S.
Published: December 2003

Dithiole and cyclopentadiene rings have been introduced into functionalised cyclopropa[b]naphthalenes to provide highly coloured, conjugated and cross‐conjugated π‐extended derivatives that have varying stability. Cyclopentadienylidene‐containing cyclopropanaphthalene 18 and its dithiolylidene analogue 25 are prepared from bromophenylcyclopropanaphthalene 12, and the 1,1‐biscyclopentadienylidene 20 from dibromide 13. Use of dithiole‐containing ketones with 1,1‐bis(trimethylsilyl)cyclopropa[b]naphthalene 10 gives the π‐extended cycloproparenes 27 and 29 in Peterson olefinations that are more efficient than Wittig−Horner reactions of cyclopropanthraquinone 31 with dithiolate 24 to give the cross‐conjugated cycloproparenes 34 and 35. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Cover Picture: Aromatic Oligoamide Foldamers (Eur. J. Org. Chem. 1/2004)
Authors: Huc Ivan
Published: December 2003

The cover picture shows a photograph of a helical origami, based on a modular ring designed by David Petty, surrounded by five examples of building blocks used in aromatic oligoamide foldamers. The background is an unfolded origami paper displaying the crease pattern that codes for a well‐defined folded shape. In the ancient Japanese art of paper folding, beautiful and complex yet predictable forms arise from a series a folding steps of a sheet of paper. Each step sets the relative orientation of the two sides of the fold. Similarly, the conformations of aromatic oligoamide foldamers are determined by interactions between consecutive units. In first approximation, the overall conformation is simply predicted as a linear combination of local conformational preferences. Details are discussed in the Microreview by I. Huc on p. 17 ff. We thank Professor Louis Cuccia for his inspiration and major contribution to this image.
Capillary electrophoresis of synthetic peptide standards varying in charge and hydrophobicity
Authors: Popa Traian V. , Mant Colin T. , Hodges Robert S.
Published: December 2003

A mixture of eight structurally closely related synthetic peptides as capillary electrophoretic (CE) standards is introduced. The almost identical mass‐to‐charge ratio of the standards, coupled with their random‐coil (i.e., no secondary structure) nature, offer a potent analytical test for CE to separate peptides varying only subtly in hydrophobicity. Parameters varied to effect a separation included background electrolyte concentration, temperature, applied voltage in capillary zone electrophoresis (CZE in uncoated capillaries), as well as the introduction of hydrophobic mechanisms to the separation either through the use of micelles or C8‐coated capillaries. Our step‐by‐step approach culminated in an optimized combination of a CZE mechanism for separation of differently charged peptide groups (based on common mass‐to‐charge ratio) and an ion‐pairing mechanism (effecting a separation within each group of identically charged peptides), which we have termed ion‐interaction CZE or II‐CZE. The study clearly shows how the peptide standards allow an excellent assessment of the resolving power of CE.