Virtual combinatorial library definition

Second, the virtual library is combined according to the instructions outlined in the library definition file. An example for the oxazolidine library is given in Fig. 17.4. The keyword DIMDEF associates a list of reagent property files to one combinatorial dimension identified by a user-defined alias (e.g., ALDEHYDES). The listed reagent files are simply appended in the program. The LIBDEF keyword is followed by a user-defined library... 

The term virtual library is used quite frequently in the literature these days. Unfortunately there is no common definition on what a virtual library really is. In the simplest case it is a database of fully enumerated structures of products that are under consideration to be made. The generation of such a virtual library involves software that maps the reaction sequence and the corresponding sets of building blocks onto a combinatorial representation (7) (see Note 4). This combinatorial representation can be partially or fully enumerated to generate product structures, which are then stored in structural databases (see Note 5). Subsequently, properties and descriptors to be used in the selection process are to be calculated. As there are limitations in terms of file size etc., such virtual libraries cannot hold more than a few million products. This makes it necessary to filter out reagents (see Subheading 1.3.) prior to construction of the virtual library. 

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