- Multistep phase-switch synthesis by using liquid-liquid partitioning of boronic acids: Productive tags with an expanded repertoire of compatible reactions
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(Figure Presented) Tagging along: A system for phase-switch synthesis has been developed. The boronic acid functionality is used as a phase tag that complexes to sorbitol and facilitates compound transfer from an organic solvent to water at high pH. The phase tag can then be used in a productive reaction step to generate targeted products, thereby eliminating purification by silica gel chromatography.
- Mothana, Sam,Grassot, Jean-Marie,Hall, Dennis G.
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supporting information; experimental part
p. 2883 - 2887
(2010/07/06)
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- Preparation and uses of conjugated solid supports for boronic acids
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The invention provides novel solid supports comprising dihydroxyalkyl aminoalkyl and dihydroxyalkylaminobenzyl groups, and methods for making and using them. The supports are particularly useful for immobilizing and derivatizing functionalized boronic acids for use in solid phase synthesis, such as those used in combinatorial chemistries. The compositions and methods of the invention are also useful as scavenger solid supports, e.g., in solution-phase parallel synthesis of small molecule libraries, and for use in resin-to-resin transfer reactions via phase transfer of solid supported boronic acids under both aqueous and anhydrous conditions. The methods of the invention provide convergent solid-phase synthesis of symmetrically or unsymmetrically functionalized compounds, such as biphenyl compounds. Also provided are synthesizer devices, e.g., semiautomated parallel synthesizers.
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- Universal solid-phase approach for the immobilization, derivatization, and resin-to-resin transfer reactions of boronic acids
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Boronic acid-containing molecules are employed in a broad range of biological, medicinal, and synthetic applications. These compounds, however, tend to be difficult to handle by solution-phase methods. Herein, this problem is addressed with the development of the first general solid-phase approach for the derivatization of functionalized boronic acids. This approach is based on the use of a diethanolamine resin anchor that facilitates boronic acid immobilization by avoiding the need for exhaustive removal of water in the esterification process. The immobilization of a wide variety of boronic acids onto N,N-diethanolaminomethyl polystyrene (DEAM-PS, 1) can be performed within minutes by simple stirring in anhydrous solvents at room temperature. Evidence for the formation of a bicyclic diethanolamine boronate with putative N-B coordination was shown by 1H NMR analysis of DEAM-PS-supported p-tolylboronic acid. The hydrolytic cleavage of the same model boronic acid from the DEAM-PS resin was studied by UV spectroscopy. Hydrolysis and attachment were shown to occur under a rapidly attained equilibrium, and a large excess of water (> 32 equiv) is required to effect a practically quantitative release of boronic acids from DEAM-PS. Despite their relative sensitivity to water and alcohols, DEAM-PS-bound arylboronic acids functionalized with a formyl, a bromomethyl, a carboxyl, or an amino group can be transformed in good to excellent yields into a wide variety of amines, amides, anilides, and ureas, respectively. Ugi multicomponent reactions on DEAM-PS-supported aminobenzeneboronic acids, derivatization of multifunctional arylboronic acids, and sequential reactions can also be carried out efficiently. These new DEAM-PS-supported arylboronic acids can be employed directly into resin-to-resin transfer reactions (RRTR). This type of multiresin process helps eliminate time-consuming cleavage and transfer operations, thereby considerably simplifying the outlook of combinatorial library synthesis by manual or automated means. This concept was illustrated by a set of optimized procedures for the Suzuki cross-coupling and the borono-Mannich reactions.
- Gravel, Michael,Thompson, Kim A.,Zak, Mark,Berube, Christian,Hall, Dennis G.
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