RENE (REaction geNErator) is a program which aim is to propose new challenges to invent reactions. The proposition of new reactions is made by the construction of the set of “pseudoisomers” of a given substructure. The reactions are then written as transforms of one “pseudoisomer” into another one. The “pseudoisomers” are constructed by considering the array of bonds as a number written in base 4 and then limiting the number of possibilities by discarding the generated propositions in disagreement with the basic rules of valency. RENE was written in QuickBasic for IBM/PC and compatible microcomputers. A Windows version is planed.

The following scheme shows what we mean by “pseudoisomer” : compounds 2 to 5 are some “pseudoisomers” of substructure 1, and they can be considered as precursors or products of 1 :

The generation of “isomers” is done by the following principle : first, the program constructs a bond table with all the possible bonds between all the atoms. For the substructure 1, these bonds are indicated in dotted lines below and the corresponding bond table is generated :

The value of the bonds may vary between 0 to 3 and the bond order may be seen as a base 4 number. SO TO CONSTRUCT THE PSEUDOISOMERS WE HAVE SIMPLY TO GENERATE ALL THE POSSIBLE BASE 4 NUMBERS.  But this approach has the disadvantage to generate a great number of solutions and many of them are totally unrealistic.  So the generation is done in two steps : in the first one the program generates only the skeletons of the pseudoisomers, i.e. the bond order may be only 0 or 1 : it is a base 2 number. In the second step for each saved solutions the program generates the corresponding isomers by calculating the base 4 numbers.

This approach is interesting because teh program is very simple, but since the number of solutions is great it can’t be used for large structures.

Some examples of theoretical precursors for the acid substructure are shown below :

The two last solutions seem identical, but they are not : they involve different transformations to reach the acid :

Paper :

36 - RENE (REaction geNErator) : a program to propose new reactions by construction of isomers and related reactive sets of simple functionalized compounds. Application to acids and esters.
R. Barone, M. Arbelot, A. Baldy, M. Chanon and R. Gallo
Revue Roumaine de Chimie. 1991, 36(4-7), 581-598. (Article for professor A. Balaban’s 60th anniversary.)

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