Related Approaches

A related approach carries out lattice sums using a suitable interatomic potential, much as has been done for rare gas crystals [82]. One may also obtain the dispersion component to E by estimating the Hamaker constant A by means of the Lifshitz theory (Eq. VI-30), but again using lattice sums [83]. Thus for a FCC crystal the dispersion contributions are... 

Alternative approaches treat the adsorbed layer as an ideal solution or in terms of a Polanyi potential model (see Refs. 12-14 and Section XVII-7) a related approach has been presented by Myers and Sircar [15]. Adsorption rates have been modeled as diffusion controlled [16,17]. 

One may rationalize emulsion type in terms of interfacial tensions. Bancroft [20] and later Clowes [21] proposed that the interfacial film of emulsion-stabilizing surfactant be regarded as duplex in nature, so that an inner and an outer interfacial tension could be discussed. On this basis, the type of emulsion formed (W/O vs. O/W) should be such that the inner surface is the one of higher surface tension. Thus sodium and other alkali metal soaps tend to stabilize O/W emulsions, and the explanation would be that, being more water- than oil-soluble, the film-water interfacial tension should be lower than the film-oil one. Conversely, with the relatively more oil-soluble metal soaps, the reverse should be true, and they should stabilize W/O emulsions, as in fact they do. An alternative statement, known as Bancroft s rule, is that the external phase will be that in which the emulsifying agent is the more soluble [20]. A related approach is discussed in Section XIV-5. 

An alternative, and closely related, approach is the augmented Hessian method [25]. The basic idea is to interpolate between the steepest descent method far from the minimum, and the Newton-Raphson method close to the minimum. This is done by adding to the Hessian a constant shift matrix which depends on the magnitude of the gradient. Far from the solution the gradient is large and, consequently, so is the shift d. One... 

These polymers differ from those prepared in the traditional two-step routes in that there is a direct carbon—phosphoms bond instead of a potentially weaker O, N, or S linkage to phosphoms. A related approach has been discovered using a catalyzed polymerization of... 

Keoleian, G. and D. Menerey, Sustainahle Development hy Design Review of Life Cycle Design and Related Approaches , Air [Pg.2154]

The section on sulfonamides should be consulted for a related approach to nitrogen protection. Some of the derivatives presented there may also be applicable to amides. 

A convenient synthesis of A -3-ketones in the 5 5 series uses DDQ in one step. This introduction has to be done indirectly because of the unfavorable direction of enolization. In this scheme, advantage is taken of the equilibrated formylation at C-2 of 5i5-3-ketones. Dehydrogenation of the 2-formyl derivative (72) proceeds rapidly with DDQ and deformylation is achieved in the presence of a homogeneous catalyst. A related approach involves preparation of the 2i -bromo-5i5-3-ketone by bromination of the 2-formyl compound (72). ... 

Preparation of PhAcOZ amino acids proceeds from the chloroformate, and cleavage is accomplished enzymatically with penicillin G acylase (pH 7 phosphate buffer, 25°, NaHS03, 40-88% yield). In a related approach, the 4-ace-toxy derivative is used, but in this case deprotection is achieved using the lipase, acetyl esterase, from oranges (pH 7, NaCl buffer, 45°, 57-70% yield). 

Pyridinethiol, Et3N, CH2CI2, 95% yield. The methylthioamide group is stable to 2.5 N NaOH, THF, H2O and to 10% H2SO4, MeOH, H20. The section on sulfenamides should be consulted for a related approach to nitrogen protection. Some of the derivatives presented there may also be applicable to amides. 

A related approach is to interface an industrial promoted catalyst with a solid electrolyte (Fig. 12.2). In this case the bulk of the commercial catalyst must be conductive. This concept has been already demonstrated for the case of NH3 synthesis on Fe-based promoted commercial catalysts (BASF S6-10 RED)16 and for the case of SO2 oxidation on V2O5-K2S2O7 based catalysts (Haldor-Topsoe VK-58).17... 

In a related approach, Adam ef al. used glycolate oxidase with D-lactate dehydrogenase for the deracemization of a wide range of racemic a-hydroxy acids (20) (Figure 5.13) [23]. 

Larock has developed a new catalyst system for the Pd-catalyzed cyclization of olefinic tosylamides. Whereas typical conditions require either stoichiometric amounts of Pd(II) salts or catalytic amounts of Pd(II) in the presence of benzoquinone as a reoxidant, the new catalyst system utilizes catalytic Pd(OAc)2 under an atmosphere of O2 in DMSO with no additional reoxidant <96JOC3584>. Although o-vinylic tosylamides 76 can be cyclized to Af-tosylindoles 77 using this catalyst system, PdCla/benzoquinone is more effective for such cyclizations. Interestingly, in the case of o-allylic tosylanilides, the cyclization can be modulated to afford either dihydroindole or dihydroquinoline products. In a related approach involving a common 7i-aUyl Pd-intermediate, 2-iodoanilines were coupled with vinylic cyclopropanes or cyclobutanes in the presence of a Pd catalyst to afford dihydroindoles <96T2743>. 

Kubinyi H. QSAR Hanch analysis and related approaches. In Mannhold R, Krogsgaard-Larsen P, Timmerman H, editors, Methods and principles in medicinal chemistry, Vol. 1. Weinheim VCH, 1993. 

A similarity-related approach is k-nearest neighbor (KNN) analysis, based on the premise that similar compounds have similar properties. Compounds are distributed in multidimensional space according to their values of a number of selected properties the toxicity of a compound of interest is then taken as the mean of the toxicides of a number (k) of nearest neighbors. Cronin et al. [65] used KNN to model the toxicity of 91 heterogeneous organic chemicals to the alga Chlorella vulgaris, but found it no better than MLR. 

Kubinyi, H. QSAR Hansch Analysis and Related Approaches, VCH, Weinheim, 1993. 

This is already the 37th volume in our series on Methods and Principles in Medicinal Chemistry which started in 1993 with a volume on QSAR Hansch Analysis and Related Approaches, written by Hugo Kubinyi. An average release of roughly three volumes per year indicates the increasing appreciation of the series in the MedChem world. 1 want to express my sincere thanks to my editor friends Hugo Kubinyi and Gerd Folkers for their continuous and precious contributions to the steady development of our series. 

Y.C. Martin, Quantitative Drug Design. A Critical Introduction. Marcel Dekker, New York, 1978. H. Kubinyi, QSAR Hansch Analysis and Related Approaches. VCH, Weinheim, 1993. 

Yet another related approach to pharmacotherapy management is step protocols or step therapy. Step protocols limit access to certain drugs until less costly alternative drugs have been tried first. For example, a step protocol might require a patient to have tried a relatively low-cost antihistamine, such as chlorpheniramine, before being prescribed a more expensive nonsedating antihistamine. Step therapy procedures were in place at 68.5% of HMOs in 1998 [1]. 

Scheme 2 shows the preparation of carbene complexes starting from [L M-ER3]" = [MeCp(CO)2Mn-SiMePlt2] and [(7r-arene)(CO)2Cr-SnPh3] [12,13]. By a related approach, a cationic cyclopropenylidene complex was prepared by reaction of Cp(CO)2FeSiMe3 with l-chloro-2,3-diphenylcyclopropenylium tetrafluoroborate [14],... 

In this section, a group of related approaches is discussed in which the continuum dielectric description of the microscopic environment is replaced by a more detailed model in which the atomic details of the structure and the dynamics of the microscopic environment are taken into account. These models will be referred to here as coupled DFT/Molecular Mechanics (DFT/MM). For a general overview of coupled ab initio/Molecular Mechanics methods, see the recent reviews by Aquist and Warshel186 and by Gao187. 

In one example of this type of cyclization aminoalcohol, 288, which was obtained by conjugate addition of racemic 2-(2-hydroxyethyl)piperidine to allyl phenyl sulfone, was converted into the corresponding chloride and cyclized in the presence of LDA to give 289 as a single diastereomer (Scheme 63) <2003JOC9389>. In a related approach, the primary alcohol group was activated for a similar cyclization by transformation into a mesylate <20010L2957>. 

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