Adams transformation

In stereoselective antitheses of chiral open-chain molecules transformations into cyclic precursors should be tried. The erythro-configurated acetylenic alcohol given below, for example, is disconnected into an acetylene monoanion and a symmetrical oxirane (M. A. Adams, 1979). Since nucleophilic substitution occurs with inversion of configuration this oxirane must be trens-conilgurated its precursor is commercially available trans-2-butene. 

This transformation results in a three-dimensional space that follows the opponent color system with +a as red, —a as green, +5 as yellow, and — b as blue. CIELAB is closely related to the older Adams-Nickerson, modified Adams-Nickerson, and other spaces of the Y,a,b type, which it replaced (1,3). 

Color Difference Evaluation. Shade evaluation is comparable in importance to relative strength evaluation for dyes. This is of interest to both dye manufacturer and dye user for purposes of quaUty control. Objective evaluation of color differences is desirable because of the well-known variabihty of observers. A considerable number of color difference formulas that intend to transform the visually nonuniform International Commission on Illumination (CIE) tristimulus color space into a visually uniform space have been proposed over the years. Although many of them have proven to be of considerable practical value (Hunter Lab formula, Friele-MacAdam-Chickering (FMC) formula, Adams-Nickerson formula, etc), none has been found to be satisfactorily accurate for small color difference evaluation. Correlation coefficients for the correlation between average visually determined color difference values and those based on measurement and calculation with a formula are typically of a magnitude of approximately 0.7 or below. In the interest of uniformity of international usage, the CIE has proposed two color difference formulas (CIELAB and CIELUV) one of which (CIELAB) is particularly suitable for appHcation on textiles (see Color). 

Adam V, Lelimousin M, Boehme S, Desfonds G, Nienhaus K, Field MJ, Wiedenmann J, McSweeney S, Nienhaus GU, Bourgeois D (2008) Structural characterization of IrisFP, an optical highlighter undergoing multiple photo-induced transformations. Proc Natl Acad Sci USA 105 18343-18348... 

Adam, W., Lazarus, M., Saha-Moller, C.R. and Schreier, P. (1998) Quantitative transformation of racemic 2-hydroxy acids into (R)-2-hydroxy acids by enantioselective oxidation with glycolate oxidase and subsequent reduction of 2-keto acids with D-lactate dehydrogenase. Tetrahedron Asymmetry, 9 (2), 351-355. 

From the seminal studies of Sabatier [43] and Adams [44] to the more recent studies of Knowles [45] and Noyori [46], catalytic hydrogenation has been regarded as a method of reduction. The results herein demonstrate the feasibility of transforming catalytic hydrogenation into a powerful and atom-economical method for reductive C-C bond formation. Given the profound socioeconomic impact of al-kene hydroformylation, the development of catalysts for the hydrogen-mediated... 

Direct hydrogenation of key intermediate 248 over the Adams catalyst and subsequent lithium aluminum hydride reduction yielded the two stereoisomeric alcohols 256 and 257, which were separately transformed to ( )-corynantheal (258) and ( )-3-epicorynantheal (259), respectively, by Moffatt oxidation, followed by Wittig reaction with methyltriphenylphosphonium bromide and, finally, by demasking the aldehyde function (151, 152). 

A prime example of a Refolding model is that of the insulin protofilament (Jimenez et al., 2002). Insulin is a polypeptide hormone composed of two peptide chains of mainly o -helical secondary structure (Fig. 3A Adams et al., 1969). Its chains (21- and 30-amino acids long) are held together by 3 disulfide bonds, 2 interchain and 1 intrachain (Sanger, 1959). These bonds remain intact in the insulin amyloid fibrils of patients with injection amyloidosis (Dische et al., 1988). Fourier transform infrared (FTIR) and circular dichroic (CD) spectroscopy indicate that a conversion to jS-structure accompanies insulin fibril formation (Bouchard et al., 2000). The fibrils also give a cross-jS diffraction pattern (Burke and Rougvie, 1972). 

Acyloin condensation of diester 30a with sodium in liquid ammonia, followed by direct hydrogenation in the presence of Adam s catalyst, furnished the diol 32 in 49% yield. Diol 32 was transformed into the cyclic thiocarbonyl derivative (80% yield) which after heating with trimethylphosphite [14] afforded twistene 33 in 50% yield. Hydrogenation of 33 gave a compound identical in all respects with twistane 1. From the diester (-)-30a (+)-twistene was obtained, m.p. 35.5-36.5 °C, +... 

The oxidation of sulfides to sulfoxides (1 eq. of oxidant) and sulfones (2 eq. of oxidant) is possible in the absence of a catalyst by employing the perhydrate prepared from hexafluoroacetone or 2-hydroperoxy-l,l,l-trifluoropropan-2-ol as reported by Ganeshpure and Adam (Scheme 99 f°. The reaction is highly chemoselective and sulfoxidation occurs in the presence of double bonds and amine functions, which were not oxidized. With one equivalent of the a-hydroxyhydroperoxide, diphenyl sulfide was selectively transformed to the sulfoxide in quantitative yield and with two equivalents of oxidant the corresponding sulfone was quantitatively obtained. 2-Hydroperoxy-l,l,l-fluoropropan-2-ol as an electrophilic oxidant oxidizes thianthrene-5-oxide almost exclusively to the corresponding cw-disulfoxide, although low conversions were observed (15%) (Scheme 99). Deprotonation of this oxidant with sodium carbonate in methanol leads to a peroxo anion, which is a nucleophilic oxidant and oxidizes thianthrene-5-oxide preferentially to the sulfone. 

In their introduction to the book Transforming Leadership (1986), John Adams and Sabina Spencer have argued that a manager has to be adept in each style. Both reactivity and proactivity are needed for effective managing ... 

Adapted from Adams and Spencer (1986) and from their Organizational Transformation Workshop, Brunei University, 1987. ... 

Adams, J. and Spencer, S. (Eds) (1986). Transforming Leadership. Miles River Press. 

Weber and Adams (1995) observed the rapid reduction of the azo dye Disperse Blue 79 chemically as well as in three anoxic sediment/ water systems. Half lives were on the order of minutes to hours. An initial rapid loss of the dye was followed by a much slower rate of transformation, and, most probably, chemical or cometabolic processes were responsible for transformation. 

A15] Czajka, Adam and Andrzej Pacut, Zak s transform for automatic identity... 

S. Smith and G. Adams, Chromatographic performance and capillary gas chromatography-Fourier transform infrared spectroscopy, J. Chromatogr., 279 623-630 (1983). 

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