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James C Anderson

Publications and source records attributed to James C Anderson.

18 recordsLinked to original sources
PubMed2006

Molybdenum oxo-imido aryloxide complexes: oxo analogues of olefin metathesis catalysts.

The novel 16-electron molybdenum oxo-imido bis(aryloxide) complexes [Mo(NtBu)(O)(2,6-Me2C6H3O)2(py)] (1) and [Mo(NtBu)(O)(2,6-iPr2C6H3O)2(py)] (2) have been prepared by the salt elimination reactions of [Mo(NtBu)(O)Cl2(DME)] with the appropriate lithium aryloxide and from the cycloaddition reactions of tert-butyl isocyanate with the appropriate molybdenum dioxo bis(aryloxide) complex [Mo(O)2(OAr)2(py)n]. Complexes 1 and 2 are the first isolable and crystallographically characterized molybdenum oxo-imido aryloxide complexes. The geometry around the metal in complexes 1 and 2 is best described as a distorted trigonal bipyramid, with the imido and pyridine ligands occupying the axial positions and the oxo and aryloxide ligands in the equatorial plane. X-ray and IR data have confirmed that the imido ligand is the dominant pi donor in the complexes, resulting in an Mo-O bond order of less than 2.5. Reaction of [Mo(NtBu)(O)Cl2(DME)] with Li(OCH2tBu) instead gave the novel complex [Mo(NtBu)(OCH2tBu)3Cl(py)] (3).

Journal Article↗
PubMed2006

Customer value propositions in business markets.

Examples of consumer value propositions that resonate with customers are exceptionally difficult to find. When properly constructed, value propositions force suppliers to focus on what their offerings are really worth. Once companies become disciplined about understanding their customers, they can make smarter choices about where to allocate scarce resources. The authors illuminate the pitfalls of current approaches, then present a systematic method for developing value propositions that are meaningful to target customers and that focus suppliers' efforts on creating superior value. When managers construct a customer value proposition, they often simply list all the benefits their offering might deliver. But the relative simplicity of this all-benefits approach may have a major drawback: benefit assertion. In other words, managers may claim advantages for features their customers don't care about in the least. Other suppliers try to answer the question, Why should our firm purchase your offering instead of your competitor's? But without a detailed understanding of the customer's requirements and preferences, suppliers can end up stressing points of difference that deliver relatively little value to the target customer. The pitfall with this approach is value presumption: assuming that any favorable points of difference must be valuable for the customer. Drawing on the best practices of a handful of suppliers in business markets, the authors advocate a resonating focus approach. Suppliers can provide simple, yet powerfully captivating, consumer value propositions by making their offerings superior on the few elements that matter most to target customers, demonstrating and documenting the value of this superior performance, and communicating it in a way that conveys a sophisticated understanding of the customer's business priorities.

Commerce↗
PubMed2005

Chirality transfer in the aza-[2,3]-Wittig sigmatropic rearrangement.

The aza-[2,3]-Wittig sigmatropic rearrangements of substrates derived from enantiomerically pure alanine, valine and serine with phenyl and ester anion stabilising groups were investigated for their efficiency in chirality transfer. It was found that a methyl substituent at the stereogenic centre of the rearrangement precursors was inadequate to control the alkene stereoselectivity and enantioselectivity of the rearrangement. Ester stabilised anions of valine and serine derivatives were the most successful with up to 66% yield, 14 : 1 alkene (E)-stereoselection and 88% chirality transfer. A limitation to the steric bulk of the stereogenic centre was noted in that the substituent has to be bulky enough to dictate alkene stereoselection, but not too large to compromise the directing effect of the activating phenyldimethyl silyl substituent on the anion stabilising group. Experimental evidence suggested a possible complimentary coordinating effect of an O-MOM serine substituent, which may assist alkene stereoselectivity and enantioselectivity.

Amino Acids↗
PubMed2005

An asymmetric nitro-Mannich reaction applicable to alkyl, aryl, and heterocyclic imines.

[reaction: see text] A protocol for the enantioselective nitro-Mannich coupling between alkyl, aryl, and heterocyclic p-methoxybenzylimines and trimethylsilylnitropropanate catalyzed by a chiral tBu-BOX Cu(II) catalyst is described. It uses the lowest reported loading of commercially available metal catalyst and chiral ligand, and gives the highest yields and selectivities for a broad substrate range including nonaromatic aldimines. The resultant beta-nitroamines are obtained in 70-94% enantiomeric excess in good yield and can be readily reduced to synthetically useful 1,2-diamines.

Journal Article↗
PubMed2005

Asymmetric aza-[2,3]-Wittig sigmatropic rearrangements: chiral auxiliary control and formal asymmetric synthesis of (2S, 3R, 4R)-4-hydroxy-3-methylproline and (-)-kainic acid.

A survey of 16 different chiral auxiliaries and a variety of strategies found that an (-)-8-phenylmenthol ester of a glycine derived migrating group can control the absolute stereochemistry of aza-[2,3]-Wittig sigmatropic rearrangements with diastereoselectivities of ca. 3 : 1 with respect to the auxiliary. In two specific examples, ca. 50% yields of enantiomerically pure products were obtained after chromatographic purification. These were synthetically manipulated with no erosion of stereochemistry into intermediates that completed formal asymmetric syntheses of (+)-HyMePro and (-)-kainic acid.

Kainic Acid↗
PubMed2005

Synthesis and antibacterial activity of hydrolytically stable (-)-epicatechin gallate analogues for the modulation of beta-lactam resistance in Staphylococcus aureus.

Hydrolytically more stable analogues of (-)-epicatechin gallate (ECg) have been synthesised from ECg where an amine or amide function has been substituted for the ester linkage that joins the C-ring with the galloyl D-ring. Sub-inhibitory concentrations (25 mg/L) of the amide analogue 7, possessing the natural C-3 stereochemistry, were able to reduce the resistance to oxacillin of three strains of methicillin resistant Staphylococcus aureus (BB 568, EMRSA-15 and EMRSA-16) comparable to levels achieved with ECg.

Anti-Bacterial Agents↗
PubMed2005

Scope and limitations of the nitro-Mannich reaction for the stereoselective synthesis of 1,2-diamines.

The acetic acid-promoted addition of lithium nitropropanate and the Lewis acid-catalyzed [Sc(OTf)3, Cu(OTf)2, or Ti(OiPr)4] addition of trimethylsilyl nitropropanate to a range of heteroaromatic and simple aliphatic aldimines gave anti-rich (approximately 3-19:1) beta-nitroamines in >95% yields as the kinetic products. It was found that a nonpolar N-imine protecting group was essential for reactivity with the o-methoxybenzyl (OMB) group giving better selectivities and yields than p-methoxybenzyl (PMB) or p-methoxyphenyl (PMP) in the Lewis acid-catalyzed addition reactions. Reduction with SmI2, treatment with COCl2, followed by OMB deprotection gave diastereomerically pure cis-imidazolidinones in 55-79% overall yield from imine. Preliminary results have shown that acetic acid can catalyze the reaction of N-OMB-benzylideneamine with nitropropane, used as solvent, to give the thermodynamically more stable syn-beta-nitroamine product.

Journal Article↗
PubMed2004

Vinyldimethylphenylsilanes as safety catch silanols in fluoride-free palladium-catalyzed cross-coupling reactions.

A series of five structurally diverse vinyldimethylphenylsilanes have been shown to undergo a fluoride-free one-pot palladium-catalyzed cross-coupling reaction with phenyl iodide to give ipso coupled products in 62-86% yield. The limitations of this present protocol lie in the activation of Si-Ph vs protodesilylation by KOTMS/18-C-6, which seems sensitive to the sterics of cis substituents, but not geminal substituents.

Journal Article↗
PubMed2004

Modulation of beta-lactam resistance in Staphylococcus aureus by catechins and gallates.

Aqueous extracts of Japanese green tea (Camellia sinensis) are able to reverse beta-lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA). We have attributed the capacity to reverse oxacillin resistance in the homogeneous PBP2a producer BB568 and in EMRSA-16 to (-)-epicatechin gallate (ECG) and (-)-catechin gallate (CG). Minimum inhibitory concentration (MIC) values for oxacillin were reduced from 256 and 512 to 1-4 mg/l, respectively, in the presence of these polyphenols. In addition, (-)-epigallocatechin gallate (EGCG) had a moderate capacity to modulate oxacillin activity against S. aureus BB568, but none against EMRSA-16. ECG, CG and EGCG increased the sensitivity of EMRSA-15 to oxacillin. The gallate moiety was essential for the oxacillin-modulating activity of ECG, as both (-)-epicatechin and (-)-epicatechin-3-cyclohexylcarboxylate were unable to reverse resistance to oxacillin. Gallic acid and three alkyl gallates (methyl gallate, propyl gallate, and octyl gallate) did not modulate beta-lactam resistance in MRSA. Octyl gallate exhibited direct antibacterial activity against S. aureus BB568 (16 mg/l). Modulation of beta-lactam resistance by ECG significantly enhanced the activities of flucloxacillin and the carbapenem antibiotics imipenem and meropenem against 40 MRSA isolates, with MIC(90) values for the antibiotics reduced to the susceptibility breakpoint or below. Consequently, EGCG, CG and, particularly, ECG warrant further investigation as agents to combat beta-lactam resistance in S. aureus.

Anti-Bacterial Agents↗
PubMed2003

Synthesis of planar chiral ferrocenyl 1,3-diamines and 1,3-amino ethers.

The efficient syntheses of novel planar chiral 1,3-diamines and 1,3-amino ethers with an oxy or amino function directly bound to the cyclopentadienyl ring of ferrocene has been developed. The key reaction is the Cu2O promoted substitution of (pR)-N,N-diisopropyl-2-iodoferrocenecarboxamide with either phthalimide or AcOH to introduce nitrogen or oxygen functionality onto the cyclopentadienyl ring. The enantiomerically pure iodoferrocene derivative is available from the known enantioselective ortho-lithiation of N,N-diisopropylferrocenecarboxamide with n-BuLi-sparteine. In the course of these studies the synthesis of a novel C2 symmetric C-2 dimer of N,N-dimethyl-1-ferrocenylethylamine was characterised by single crystal X-ray diffraction.

Journal Article↗
PubMed2003

Investigation of the asymmetric ionic Diels-Alder reaction for the synthesis of cis-decalins.

The ionic Diels-Alder reaction, whereby an alpha,beta-unsaturated acetal in combination with a Lewis or Bronsted acid forms an equilibrium concentration of an activated dienophile, has been developed to provide an enantioselective synthesis of cis-decalins. Cyclohex-2-enone type chiral acetals of (2R,3R)-butane-2,3-diol have been screened against Lewis and Brønsted acids with a variety of dienes and are efficient for the synthesis of a limited subset of cis-decalin structures. Diastereoselectivities of 73% and 82% have been found for the asymmetric ionic Diels-Alder reaction between the chiral acetal derivatives of cyclohex-2-enone (6) and 2-methylcyclohex-2-enone (18) with 2,3-dimethyl-1,3-butadiene (7). Terminal substituents on the diene partner in general render the system unreactive. However a synthetically useful cis-decalin 31, derived from the reaction of 2-methylcyclohex-2-enone and Z-3-t-butyldimethyl-silyloxypenta-1,3-diene has been prepared in enantiomerically pure form in 74% isolated yield using this asymmetric ionic Diels-Alder protocol.

Journal Article↗
PubMed2003

Total synthesis of (+/-)-kainic Acid with an aza-[2,3]-Wittig sigmatropic rearrangement as the key stereochemical determining step.

A flexible route to the kainoid skeleton is exemplified by the synthesis of (+/-)-kainic acid from 3-butyn-1-ol. The route relies on the aza-[2,3]-Wittig sigmatropic rearrangement to efficiently install the relative stereochemistry between C2-C3. The C4 stereocenter was derived from a diastereocontrolled iodolactonization. The aza-[2,3]-Wittig rearrangement potentially allows structural diversity at C3 and the displacement of the tosyloxy group with retention of stereochemistry allows structural diversity at C4. The trans-C2 carboxylic acid functional group was found to be the most important for retention of stereochemistry at C4 upon treatment with a higher order cyano cuprate reagent.

Alkylation↗
PubMed2003

July 2002: 66-year-old female with a one-year history of progressive left proptosis.

The July 2002 Case of the Month (COM). This 66-year-old Caucasian female presented with gradually increasing protrusion of her left eye over a one-year period. She complained of increased tearing and foreign body sensation. The physical examination revealed a visual acuity of 20/20, normal color testing, full vision field with motility of her left eye limited in lateral gaze. Pupils were round, symmetric, with no afferent pupillary defect noted. On external examination, her left eye was grossly proptotic with resistance to retropulsion. She had 4 mm proptosis of the left eye. Computed tomography and MR imaging demonstrated a left retro-orbital mass with gadolinium enhancement and focal remodeling of orbital bones. She underwent surgical resection of tumor with a diagnosis of solitary fibrous tumor, and postoperatively she was symptom free. The histopathological differential diagnoses of spindle cell neoplasms of the orbit are discussed. Five months after surgery, no evidence of tumor recurrence was seen on neuroimaging and her vision was 20/20.

Aged↗
PubMed2002

No increased herniation of the cerebellar tonsils in a group of patients with orthostatic intolerance.

Orthostatic intolerance, seen predominantly in young women, is characterized by symptoms of lightheadedness, fatigue and palpitations in the upright posture. With standing, plasma norepinephrine levels rise dramatically and heart rate often increases by more than 30 beats per minute, although blood pressure does not usually fall. A theory recently popularized in the media suggests that some cases of orthostatic intolerance are related to hindbrain compression, with or without a Chiari I malformation. As a preliminary investigation of this hypothesis, head or cervical spine MRI scans from 23 females with orthostatic intolerance were reviewed. The cerebellar tonsils averaged 0.3 +/- 1.9 mm below the foramen magnum. These results were compared to measurements from a control group averaging 0.4 +/- 2.6 mm above the foramen magnum (P > 0.05). Tonsillar depression of at least 3 mm occurred in 13 % of both the patient group and the control group. Tonsillar herniation was not found to influence supine or upright blood pressure, heart rate or plasma norepinephrine levels in the patients. We conclude that herniation of the cerebellar tonsils is not a common cause of orthostatic intolerance. However, the single measurement of tonsillar depression might underestimate the number of patients with hindbrain compression.

Adult↗
PubMedDate not supplied

Basal ganglia: anatomy, pathology, and imaging characteristics.

Several cases of bilateral basal ganglia lesions seen in magnetic resonance imaging initiated a review of the anatomy, pathology, and differential diagnoses of this region. There are a variety of disease entities that present as symmetrical basal ganglia abnormalities. Although these findings may not indicate a specific diagnosis, knowledge of the characteristics of diseases that affect this area can limit the differential considerations. Clinical information is often essential for narrowing the possible pathology that can be found here. The purpose of this article is to review the anatomy of the basal ganglia, the pathologies, clinical histories, and imaging characteristics that can cause bilateral basal ganglia lesions.

Basal Ganglia↗