Target compounds defined

WIN 64821 (10) and (—)-ditryptophenaline (11) syntheses [7], not only effectively differentiated the two amide moieties but also most importantly marked the first in a series of stereochemical transfer steps in which the stereochemistry of the constituent L-amino acids was relayed to ultimately define each of the relative and absolute stereochemical configurations at all eight stereogenic centers found in the target compound. Finally, /V-methylation of the base-sensitive amide in 77 % yield using methyl iodide and potassium carbonate in acetone completed the 5-step synthesis of our key tetracyclic bromide monomer starting from commercially available amino acid derivatives. 

Defining the structural identity of a resin-bound compound in solid-phase library by marking the individual resin beads with a tag that is unique to the attached target compound... 

Jacobsen s five criteria were picked for a laboratory situation in which a synthetic target compound, sometimes not even optimized for its purpose, was needed quickly and probably just once or at best a few times, and on a laboratory scale. The criteria were not developed for the situation of large-scale, continual production of a narrowly defined but well-known product. One-time laboratory synthesis protocols have to be concerned about instant availability and instant cost of catalysts (usually not under the influence of the user) but re-usability of catalyst and process performance criteria such as volumetric productivity are not and do not have to be considered. For large-scale continual production the situation is often reversed. 

Figure 13.11 Principle of PCA-based library design. The original data space X is spiked with a virtual optimum (denoted by a star in a) whereas in b) a set of reference compounds defines the optimum), thereby defining a target area for compound selection. After PCA, the relevant principal components (PC) span an orthogonal space, and distance criteria are used for picking compounds that are closest to the a) virtual optimum, or b) reference compounds.

The role of organic synthesis in science and in practice is not easily defined in an unambiguous way. To answer the question about the goals of an organic synthesis, one cannot simply refer directly to the application or usefulness of the target compound, even if the term usefulness is understood in the broadest sense. Nevertheless, we would like to start this chapter with just this obvious case — the synthesis of unquestionably useful organic compounds. 

These are QSAR techniques, sometimes also referred to as CoMFA-like approaches, based on descriptors defined as molecular interaction energy values representing - molecular interaction fields or, in other words, the interaction energy between a - probe and a target compound embedded in a grid. 

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