RESUMO
An aldol-based build/couple/pair (B/C/P) strategy was applied to generate a collection of stereochemically and skeletally diverse small molecules. In the build phase, a series of asymmetric syn- and anti-aldol reactions were performed to produce four stereoisomers of a Boc-protected γ-amino acid. In addition, both stereoisomers of O-PMB-protected alaninol were generated to provide a chiral amine coupling partner. In the couple step, eight stereoisomeric amides were synthesized by coupling the chiral acid and amine building blocks. The amides were subsequently reduced to generate the corresponding secondary amines. In the pair phase, three different reactions were employed to enable intramolecular ring-forming processes: nucleophilic aromatic substitution (S(N)Ar), Huisgen [3+2] cycloaddition, and ring-closing metathesis (RCM). Despite some stereochemical dependencies, the ring-forming reactions were optimized to proceed with good to excellent yields, providing a variety of skeletons ranging in size from 8- to 14-membered rings. Scaffolds resulting from the RCM pairing reaction were diversified on the solid phase to yield a 14 400-membered library of macrolactams. Screening of this library led to the discovery of a novel class of histone deacetylase inhibitors, which display mixed enzyme inhibition, and led to increased levels of acetylation in a primary mouse neuron culture. The development of stereo-structure/activity relationships was made possible by screening all 16 stereoisomers of the macrolactams produced through the aldol-based B/C/P strategy.
Assuntos
Aldeídos/química , Descoberta de Drogas/métodos , Inibidores de Histona Desacetilases/síntese química , Inibidores de Histona Desacetilases/farmacologia , Histona Desacetilases/metabolismo , Compostos Macrocíclicos/síntese química , Compostos Macrocíclicos/farmacologia , Animais , Produtos Biológicos/síntese química , Produtos Biológicos/química , Produtos Biológicos/farmacologia , Avaliação Pré-Clínica de Medicamentos , Inibidores de Histona Desacetilases/química , Compostos Macrocíclicos/química , Camundongos , Modelos Moleculares , Conformação Molecular , Estereoisomerismo , Especificidade por SubstratoRESUMO
The two-step functionalization of 30,000 SynPhase Polystyrene (PS) Lanterns in a 30-L glass process reactor is described. The first step involves bromination of the polystyrene backbone to afford an aryl bromide handle. Subsequent Suzuki cross coupling with the trialkylborane generated in situ from the reaction of allyldiisopropyl(4-methoxyphenyl)silane and 9-BBN provided an alkylsilyl linker ready for loading of various alcohols for solid-phase synthesis applications.
Assuntos
Técnicas de Química Combinatória/métodos , Poliestirenos/síntese química , Álcoois/química , Reagentes de Ligações Cruzadas , Halogenação , SilícioRESUMO
The concentration of reactive metal hydride (Met-H) reducing agents can be determined (in < or = 20 min) using No-D NMR spectroscopy. The method involves (i) reacting Met-H with an excess of p-methoxybenzaldehyde, (ii) quenching with excess acetic acid, (iii) recording the No-D NMR spectrum of this homogeneous mixture, and (iv) deducing the concentration of Met-H from the % conversion (as measured by integration). By a conceptually related method, the titer of the basic alkali metal hydrides KH and NaH can also be determined.
Assuntos
Hidrogênio/química , Espectroscopia de Ressonância Magnética/instrumentação , Espectroscopia de Ressonância Magnética/métodos , Indicadores e Reagentes/química , Estrutura Molecular , TitulometriaAssuntos
Compostos Bicíclicos Heterocíclicos com Pontes/síntese química , Lactonas/química , Produtos Biológicos/síntese química , Produtos Biológicos/química , Compostos Bicíclicos Heterocíclicos com Pontes/química , Ciclização , Ácidos Dicarboxílicos/química , Cinética , Lactonas/síntese química , EstereoisomerismoRESUMO
[reaction: see text] The title technique is a convenient and powerful method for directly monitoring or assaying any reaction mixture or reagent solution. Examples of some common processes (Fischer esterification, lithiation, butyllithium/THF compatibility, olefin metathesis, and a quantification assay), each interrogated in its native solvent, are presented. The spectral data are easy to acquire, and the information content makes a compelling case for routine use of No-D NMR spectroscopy.
Assuntos
Espectroscopia de Ressonância Magnética/métodos , Deutério , Indicadores e Reagentes , Prótons , SoluçõesRESUMO
A strategy has been developed in which mechanistically distinct lactonization reactions are used to prepare diastereomeric delta-lactones relevant to the C1-C9 fragment of (+)-peloruside A. Depending upon which of two reaction types is used, the central (C5) hydroxyl group can be directed to differentiate the C1 versus C9 termini of pseudosymmetric substrates to provide diastereomeric lactones. Thus, the 5-hydroxy-1,9-diester substrate 1 (an azelaic ester) cyclizes under classical (acid- or base-catalyzed) lactonization conditions to give a predominance of one diastereomer, whereas the 5-hydroxy-1,10-diene congener 2 provides the opposite sense of diastereoselectivity when subjected to ozonolytic lactonization (O3, MeOH, NaOH, at -78 degrees C). Thus, this under-utilized oxidative transformation is mechanistically orthogonal to the classical reaction.