Pooling strategies

Wilson-Lingardso, L., Davis, P.W., Ecker, D.J., Hebert, N., Acevedo, O., Sprankle, K., Brennan, T., Schwarcz, L., Freier, S.M., and Wyatt, J.R., Deconvolution of combinatorial libraries for drug discovery experimental comparison of pooling strategies, J. Med. Chem., 1996, 39, 2720-2726. 

In addition to selecting an appropriate assay, it is also necessary to have a pooling strategy. It is more efficient to test many compounds per well on the microplate, rather than one. If one could test 100 compounds per well, then the standard 96-well plate would enable almost 10,000 compounds to be evaluated in one experiment. (Currently, multiwell plates containing more than 96 wells are routinely being used.) To facilitate effective pooling, the library of compounds is usually divided into a number of nonoverlapping subsets. 

The synthetic strategy employed during the combinatorial syntheses can be used to assist in determining these pooling strategies. In random incorporation syntheses, a single bead could contain millions of different molecular species. In mix and split syntheses (also called pool and divide syntheses or one bead-one compound syntheses) only one compound is attached to any given solid-phase synthetic bead. 

Kauffman and Macready [65] examined pooling strategies on NK fitness landscapes. They simulated two pooling strategies that differed in the order in which amino acid sites were used to partition the best pool each cycle (order of unrandomization) and the number of subpools they were partitioned into. Results were qualitatively the same for both. A pool s fitness was defined as the average fitness of its members. 

Fig. 19. Distributions offitnesses of the best pool during successive cycles (iterations) ofa pooling strategy. Simulations are on an NK landscape with N= 6 and 20 monomers per site, corresponding to a hexapeptide. The initial 400 pools are fixed at sites 3 and 4. The second pools are fixed at sites 2 and 5, and the third pools are fixed at sites 1 and 6. (a) K=0 (b) K=3. (From Ref. 65.)...

The pooling strategies should be reexamined with the correct bulk affinity calculations and the areas for further study outlined above. 

Konings DAM, Wyatt JR, Ecker DJ, Freier SM, Deconvolution of combinatorial libraries for drug discovery theoretical comparison of pooling strategies, J. Med. Chem., 39 2710-2719, 1996. 

Archbold, E., Mitchel, S., Hanson, D., Hull, B., Galo, L. M., and Monzon, O. (1991). Serum-pooling strategies for HIV screening Experiences in Trinidad, Ecuador, and the Phillippines. VII International Conference on AIDS Abstract Book, 2, 331. 

Simpkins and co-workers were the first to use an asymmetric catalytic process in (-)-anatoxin-a synthesis (Newcombe and Simpkins, 1995) instead of resorting to the chiral pool strategy. Their total synthesis of (-)-anatoxin-a relied on an enantioselective enolisation reaction of a readily available ( )-3-tropinone (33), by a chiral lithium amide base (34) (Bunn et al. 1993a, 1993b) and subsequent cyclopropanation/ring expansion reaction giving the ketone 37 (Scheme 7.8). 

The cut point location strategy in chromatography is important because it determines the product purity, yield and product concentration to be processed forward. Use of detectors which allow on-line monitoring of the column effluent facilitates development of robust pooling strategies. Common strategies for identification of the start of the pool... 

Detailed analysis of the synthesis of an important chiral auxiliary by the chiral pool strategy. 

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