Computer-Assisted Organic Synthesis: An Undergraduate Experiment M. P. Bertrand, H. Montl, and R. Barone Faculte des Sciences et Techniques de St. Jerome Rue H. Poincare, 13397 Marseille cedex 13, France
Computer-assisted instruction is an expanding field connected with computer development, and numerous chemistry CAI programs are available (I). Among these there are two groups of programs specifically designed for organic synthesis: 1) those that are exclusively teaching tools (2-9) and 2) research programs adapted for teaching purposes (10, 11) The program described here belongs to the second group (12-14). It is called SOS (Simulated Organic Synthesis). A mechanistic approach is used to describe reactions (13). It has been adapted to an Apple I1 microcomputer (15), which makes i t readily accessible to every laboratory and convenient for students. The flowchart of SOS is presented in Figure 1. The target molecule, (+-) ar-turmerone (I@, a monocyclic terpene, has been isolated from the essential oils of turmeric rhizomes of Curcuma longa, a herbaceous perennial plant, used both as a condiment and as a dyestuff. This compound has been selected for its simple structure (no stereochemical problems are encountered during the synthesis), and its applied interest. The student's work is divided into two parts: 1) retrosynthetic analysis of the target molecule by means of the SOS program and 2) practical realization of one synthetic pathway. The search for possible approaches to ar-turmerone is a direct application of the retrosynthesis lecture given to the students. Figure 2 gives an example of what the student sees on the
(Idenufmumof important StTuCtural features
screen during the session. Among the more reasonable pathways proposed, the students should select path 6, after discussion with the instructors. (See Figure 3.) The reasons for that particular choice are: 1) this synthesis allows the use of modern synthetic reagents (organolithium compounds, dialkyl cuprates, . . . ) and makes the students familiar with analytic techniques (VPC, TLC, LC, IR, NMR); 2) students are challenged by the idea of reproducing published results (cf. 16c for experimental procedure). Students are especially interested to discover that they can plan a synthesis and work it out so that they obtain the target molecule. For them this work is closely related to concrete problems of organic synthesis laboratories. The program runs on a 64K Apple 11+ microcomputer with two disk drives. It may be made available upon request to the author (R. B.).
Synthetic Design on a Pocket Computer Patrlck Pollet lnstitut National des Sciences Appliquees 20 Rue A. Einstein. F69100 Villeurbanne, Lyon, France The program SYNDES presented below is an implementation of the Hendrickson orotocol for svstematic svnthetic design (17). This logic-oriented strategy can he ~uhdivided into threesteos: 1) dissection ofthe tareet moleculeskeleton in the most efficient ways to produce discrete number of independent synthetic plans (bondsets), 2) numerical generation of the reactions and of the functionality required on every synthon to reach the target compound by the shortest routes (self-consistent syntheses), and 3) matching to real chemistry the generalized routes thus produced.
a
Cholce of a
precursor as
nngs. nucleophlllc centers 1
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READ A REACTION (a)
(YIN)
Figure 2. Screen display from SOS program.
PRESENT I N THE TARGET?
THIS PRECURSOR
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Figure 1. Flowchart of SOS. Each transform contains the following information: a minimum substructure required in target; questions concerning the target written in a Basic-like language (IF. .THEN . .ELSE);a description at how to accomplish the transformation (which bonds to break, etc.). 824
Journal of Chemical Education
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Figure 3. Synthetic pathways to target (t-)a,-turmerone. SOS program
