ACDC

The crystal structure of [Cu(Me2dtc)2] shows that it possesses a center of S3rmmetry, with the copper octahedrally co-ordinated to six S atoms, two Cu-S bonds being longer than the other four (424). Choi and Wasson (425) showed that there is only Cu-S bonding in [Cu(acdc)2] (acdc = 2-amino-l-cyclopentadienyl-l-dithiocarboxylate). 

Determine how far to move along the current search direction dc, starting from the current point xc. This distance ac is most often an approximation of the value of a that minimizes the objective function fixc + adc) and is used to determine the next point xn = (xc + acdc). 

NHEERL J1 mouse embryonic stem cells, 9-day (mESC) ACDC assay for cell number and... 

Barrier M, Jeffay S, Nichols HP, Chandler KJ, Hoopes MR, Slentz-Kesler K, Himter ES 111 (2011) Mouse embryonic stem cell adherent cell differentiation and cytotoxicity (ACDC) assay. Reprod Toxicol 31 383-391... 

We then thought to carry out conjugate reduction of a,P-unsaturated ketones. However, neither these ACDC-catalysts, nor the commonly... 

S.C. PanandB. List s paper spans the whole field of current organocat-alysts discussing Lewis and Brpnsted basic and acidic catalysts. Starting from the development of proline-mediated enamine catalysis— the Hajos-Parrish-Eder-Sauer-Wiechert reaction is an intramolecular transformation involving enamine catalysis—into an intermolecular process with various electrophilic reaction partners as a means to access cY-functionalized aldehydes, they discuss a straightforward classification of organocatalysts and expands on Brpnsted acid-mediated transformations, and describe the development of asymmetric counteranion-directed catalysis (ACDC). 

Not to be confused with ACDC, which are rather cytotoxic too, but selectively for the cells in the inner ear. 

Bussolini F, Tetta C, Camussi G. Spedfic binding of H-PAF by human PMN. Agentsand Acdc 1984 15 15-17... 

The oxovanadium(IV) complex 19 of 2-amino-1-cyclopentene-1-dithiocar-boxylato (acdc) and the complex with JV-methylated acdc ligands 20 have both been synthesized and characterized by various spectroscopic measurements in order to elucidate the coordination environment of the acdc ligand (Fig. 6) [53]. Simply introducing a methyl group onto the amino group to form 20 causes a change in the coordination around the oxovanadium(lV) center compared to... 

The lability of Hg(acdc)2 61 and the rapid interaction with elemental mercury electrode strongly influence the nature of the redox processes observed at mercury electrodes. In the reduction of 61, reduction at a mercury electrode occurs according to an overall two-electron step, as shown in Scheme 14, although mercury(I) is implicated as an intermediate [116]. 

Scheme 14 The redox processes of Hg(acdc)2 observed at a mercury electrode...

AJ Mangram, et al. ACDC HICPAC Guideline for Prevention of Surgical Site Infection, 1999. AJIC 27(2) 97-133, 1999. 

It is the control of the reactivity of this carbamate anion which has allowed us to generate in quantitative yields either urethanes or isocyanates directly. By understanding those factors which promote the nucleophilicity of the carbamate oxygen, we have discovered how to generate urethanes directly from either primaiy or secondary amines (Activated Carbon Dioxide Chemistry-I (ACDC-I) (12, 13, 15-18). A key aspect of this chemistry was our discovery that carbamate anions can serve as excellent nucleophiles, when a suitable tertiary amine base is utilized to generate the carbamate anion in the reaction of carbon dioxide with a primary or secondary amine (equation 4). By proper choice of the tertiary amine co-base, which in general does not react with CO2 under the mild conditions employed. 

As noted above, the reaction of amines, carbon dioxide and electrophiles has been reported in the literature, but the products generally are derived from attack on the nitrogen center, liberating CO2 and producing the substituted amine or amide. Both the ACDC-I and -II chemistries rely on the production of the carbamate anion from the reaction of carbon dioxide with the substrate amine. Very few reports have appeared which have addressed the issue of utilizing the carbamate anion as an oxygen- nucleophile in direct substitution reactions (9-14). 

Stanhope, N., Crowley-Murphy, M., Vincent, C. et al. (1999) An evaluation of adverse inddent reporting. Journal of Evaluation in Clinical Jh acdce, 5(1), 5-12. 

Jorgensen Asymmetnc epoxidation of er ls List Developmeni of ACDC catalysis 2007... 

In 2008, List s group developed an epoxidation using asymmetric counteranion-directed catalysis (ACDC) [177]. In this work, the epoxidation of 1,2-disubstituted enals (33) and (3,(3-disubstituted, a, 3-unsaturated aldehydes (115) was explored. Instead of using a chiral amine (e.g. Jprgensen-Hayashi s catalyst), an achiral amine and a chiral counteranion (a phosphoric acid derived from BINOL), were employed. 

Besides the utilization of chiral secondary amines to achieve a LUMO-lowering activation as well as face discrimination, the use of achiral secondary amines in combination with a chiral counterion also proved to be highly promising for such transformations. This strategy resembles the use of achiral metal catalysts in combination with a chiral ligand to achieve a stereoselective transformation (206-208). It is due to Benjamin List that the elegant concept of asymmetric counteranion-directed catalysis (ACDC) has found widespread applications in organocatalysis at the present time (209-212). 

Bringing together the concept of aminocatalysis and the activation mode of chiral phosphoric acids. List and co-workers introduced the concept of asymmetric counter anion directed catalysis (ACDC) and they applied this idea to the asymmetric reduction of enals 47 (Scheme 23) [ 135]. The catalytic species is formed by an achiral ammonium ion 60 and a chiral phosphate anion 59 derived from 3,3 -bis(2,4,6-triisopropylphenyl)-1,1 -binaphthyl-2,2 -diyl hydrogen phosphate 9 (TRIP). 

Scheme 23 ACDC approach appUed to the reduction of enals 47...

FEGSEM images to show the structure of optimized ACDC oxides on clad 2024-T3 clad aluminum. Top image shows the through thickness, middle image the outer oxide, bottom image the inner oxide... 

Alternating Current-Direct Current Anodizing (ACDC Anodizing)... 

Wedge crack length data to show the influence of varying the AC anodizing parameters and electrolyte temperature for the ACDC process note a 10 m, 20 V DC process has been deposited beneath each AC film (Cartwright 2005)... 

The validity of this approach was further demonstrated by the poor enantiose-lectivities obtained for proline-based catalytic centers that are imable to self-assemble with alkaloids, demonstrating that enantioselectivity is indeed due to the two-component supramolecular complex. As stated by the authors, these results indicate that this catalytic system is different from the reported asymmetric counteranion-directed catalysis (ACDC) [21] since in that case the stereocontrol is achieved mainly through steric effects instead of hydrogen bonding. 

The discrimination of the face of the chiral carbenium ion is determined by the hindrance of the flanking groups. In the case of chiral Bronsted acids, the chiral counter ion, formed after effective protonation or partial donation of the proton, surrounds the created cationic intermediate. One face of the intermediate is effectively covered by the chiral counter ion and the nucleophile reacts with the less covered face. However, in many SNl-type transformations mediated by Lewis acids, a transition state in which a couple of protons interact with the phosphates is often invoked. This double interaction seems cmcial and only a partial success in the use of nucleophiles was achieved. Nevertheless, a series of successful S l-type reactions were discovered and are highUghted in this section. The chiral ion pairs between phosphate anions and iminiums [64] or metal ions were developed [65]. This powerful strategy is called asymmetric counteranion-directed catalysis (ACDC) and it has been applied successfully to several innovative transformations. The generation of carbenium ion in situ from alcohol, with the use of acids able to form a tight chiral ion pair with the phosphate anion, can be used in S il-type... 

In the case of enals, the most common catalysts are secondary chiral amines, which can be divided into two large groups (i) amines substituted with a bulky group and (ii) amines with hydrogen-bond-directing groups. Another possible type of catalyst for this activation mode arises from ACDC (asymmetric counterion direct catalysis) developed by List. In these catalysts either a chiral or non-chiral amine forms a chiral ionic pair with a chiral phosphoric acid. A different possibility is the use of a primary chiral amine and a strong acid. These latter methods have... 

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