Optimized methods for utilizing and analyzing dialkylamine tags in encoded combinatorial chemistry are reported. A previously described LC/fluorescence method has been shortened from over 1 h to 6 min. A novel ion exchange LC/MS method for decoding has been developed which is both fast and rugged. The use of quantitative encoding schemes is described. These new techniques have allowed a simplified, automated sample preparation scheme, and over 300 encoded bead samples can be read in a day.

The preparation of novel N-Boc-alpha-amino-5-acyl Meldrum's acids is described. The synthetic inaccessibility and instability of several of these products have led to the development of a protocol that allows the synthesis of their corresponding 4-(dimethylamino)pyridine (DMAP) salts (5-AMA-DMAP's), which exhibit superior stability compared to that of the free 5-AMA. A simple and expedient ion-exchange method was developed for the quantitative removal of DMAP to liberate the synthetically useful DMAP-free form when needed.

Chemistry. -Title compounds are prepared following the 3 different ways presented. The DMAP salts [cf. (X) and (XII)] exhibit a stability superior to that of the free analogues. Simple treatment of these salts with AG50W-X2 (Bio Rad) liberates the building blocks in quantitative yields. -(RAILLARD*, S. P.; CHEN, W.; SULLIVAN, E.; BAJJALIEH, W.; BHANDARI, A.; BAER, T. A.; J. Comb. Chem. 4 (2002) 5, 470-474; Affymax, Inc., Palo Alto, CA 94304, USA; Eng.) -Lindner 05-165

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