Solid-phase synthetic methods for biaryl-based compounds were developed resulting in the construction of two 1000-member libraries. Numerous compounds were identified by high-throughput screening using whole cell screens to exhibit anti-microbial activity against Gram-positive bacteria. A series of biaryl compounds containing natural and unnatural amino acids were made to explore the SAR of the amino acid functionality.
Organic synthesis on solid-phase resins requires new applications of nondestructive analytical tools to monitor the progress of reactions. Herein we describe our novel approach to validate a five-step reaction sequence on resin. We have developed a protocol list that allows us to follow reactions step-by-step using different analytical procedures in the order of increasing experiment time. Results from these various techniques for each reaction step are contrasted and compared. The key to achieve definitive analytical data for the entire reaction sequence is the combined application of more than one analytical technique.
Application of organic synthesis to solid supports has led to the successful implementation of combinatorial chemistry in the drug discovery process. This paper describes a novel use of the Hofmann elimination of tetrasubstituted amine salts on solid-phase resin to generate diverse combinatorial libraries of trisubstituted amines. Highly pure compounds were isolated without further purification by the addition of a second resin as the source reagent to promote the required elimination. The use of mixed resin systems to generate compounds is a novel application of bead-based technologies.
The application of a new encoding technology for drug discovery is described. A combinatorial library of mercaptoacyl pyrrolidines has been prepared on a beaded polymeric support. Each polymer bead carries one library constituent in association with an oligomeric “tag,” the structure of which is a record of the specific reagents from which that library member was prepared. After the ligands were solubilized, an array of such beads was screened for angiotensin-converting enzyme inhibitory activity, and the structures of active pyrrolidines were deduced by analysis of the associated tags at sub-picomole levels. Several extremely potent enzyme inhibitors were identified, many from multiple beads. The most potent inhibitor was found to have a K i of 160 pM, ≈3-fold more active than captopril in the same assay. Direct comparison with iterative deconvolution shows that the encoded screening strategy is a much more efficient means for extracting information from such compound collections, producing more data on a larger number of active structures.
Encoded combinatorial organic synthesis has recently emerged as a powerful tool for the discovery of biologically active compounds from complex chemical libraries. This report describes a new encoding methodology that uses chemically robust secondary amines as tags. These amines are incorporated into an N-[(dialkylcarbamoyl)methyl]glycine-coding oligomer through simple chemistry that is compatible with a wide range of polymer-supported transformations useful in combinatorial synthesis. In the decoding process acidic hydrolysis of the tagging polymer regenerates the secondary amines, which after dansylation are resolved and detected at sub-picomole levels by reversed-phase HPLC. The versatility of this strategy is demonstrated here by encoded syntheses of members of several representative heterocyclic compound classes, including beta-lactams, 4-thiazolidinones, and pyrrolidines.
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Trimethylorthoformate has been found to be an effective dehydrating solvent for the formation of imines, both in the solid phase as well as solution phase.
Two concise, highly convergent strategies for the synthesis of Vitamin D derivatives are presented. Beginning with synthons of exceedingly low complexity, each approach utilizes a transition metal catalyzed intramolecular carbometalation for the stereoselective formation of the critical (bis)exocyclic diene subunit.