RESUMO
A novel Pd-catalyzed coupling of Cbz-protected proline amide with 4-bromo-5-ethoxyfuran-2(5H)-one was developed for the synthesis of the P1-P2 unit (5) of VX-765. The process afforded quantitative coupling in the presence of water, providing a 1:1 mixture of 5 and its ethoxy epimer epi-5. Compound 5 was isolated as a single diastereomer via fractional crystallization, which was stereoselectively converted to 17 via hydrogenation, and subsequently transformed to VX-765. Nine examples of the Pd coupling are presented with yields ranging from 76-98%.
Assuntos
Acrilamida/síntese química , Carbamatos/síntese química , Inibidores de Caspase , Dipeptídeos/síntese química , Dipeptídeos/farmacologia , Hidrocarbonetos Bromados/síntese química , Paládio/química , para-Aminobenzoatos , Ácido 4-Aminobenzoico/síntese química , Ácido 4-Aminobenzoico/química , Ácido 4-Aminobenzoico/farmacologia , Acrilamida/química , Carbamatos/química , Catálise , Dipeptídeos/química , Hidrocarbonetos Bromados/química , Estrutura Molecular , EstereoisomerismoRESUMO
The Pd-catalyzed regioselective C-H activation/arylation, /iodination, and/acetoxylation reactions of 4-arylpyrimidines using aryl iodides, N-iodosuccinimide, and (diacetoxyiodo)benzene respectively as coupling partners are described. Suzuki-Miyaura coupling and Sonogashira reactions of the resulting aryl iodides are demonstrated. The scalability of the C-H activation/functionalization starting with readily accessible 4-aryl pyrimidines is also reported.
RESUMO
Racemic beta(2) agonists, composed of equal amounts of (R)- and (S)-isomers, can display anomalous actions that compromise their effectiveness as asthma therapies. Loss of efficacy during regular use is characteristic of isoprenaline, albuterol and terbutaline and has in part been attributed to the biological effects of the (S)-isomer. This hypothesis was applied to the (R,R)- and (S,S)-isomers of formoterol. (R,R)-formoterol had 1000-times greater affinity (2.9 nm) to the human beta(2) adrenoceptor than (S,S)-formoterol (3100 nm), with receptor binding modulating intracellular cAMP levels. The minimum lethal intravenous (IV) dose was determined to be 100 mg/kg for (R,R)- and 50 mg/kg for (S,S)-formoterol, suggesting that the toxicity of (S,S)-formoterol may not be related to the binding of beta(2) adrenoceptors. In tissues pretreated with (S,S)-formoterol but not with (R,R)- or racemic formoterol contractions to high concentrations of carbachol were exaggerated. In vivo experiments with sensitized guinea pigs demonstrated that (R,R)-formoterol inhibited both histamine and antigen-induced bronchoconstriction with greater potency than (R,R/S,S)-formoterol while (S,S)-formoterol was ineffective. Metabolic radiolabeling experiments of (R,R)-, (S,S)- or (R,R/S,S)-formoterol with crude human liver phenolsulfotransferase (PST) determined the V(max)/K(m) values to be (0.151), (0.74) and (0.143), respectively. The reciprocal plot illustrates a 2-fold reduction in sulfation rate when (R,R)-formoterol is present as a single isomer. The data presented here suggest that (R,R)-formoterol binds to the beta(2) adrenoceptor and inhibits the contraction of bronchial tissues by spasmogens. However, (S,S)-formoterol exhibits properties inconsistent as an asthma therapeutic and may antagonize the actions of (R,R)-formoterol.