The ubiquitin-proteasome pathway plays a central role in regulation of the production and destruction of cellular proteins. These pathways mediate proliferation and cell survival, particularly in malignant cells. The successful development of the 20S human proteasome inhibitor bortezomib for the treatment of relapsed and refractory multiple myeloma has established this targeted intervention as an effective therapeutic strategy. Herein, the potent, selective, and orally bioavailable threonine-derived 20S human proteasome inhibitor that has been advanced to preclinical development, [(1R)-1-[[(2 S,3 R)-3-hydroxy-2-[(6-phenylpyridine-2-carbonyl)amino]-1-oxobutyl]amino]-3-methylbutyl]boronic acid 20 (CEP-18770), is disclosed.
Boronic esters are key intermediates in the synthesis of biologically active compounds such as thrombin and proteasome inhibitors. However, they have low hydrolytic stability both during synthetic reactions and in biological media. We report the preparation of several boronic esters and a comparative study of their stability to hydrolysis vs. the corresponding pinanediol boronic esters, which are among the most hydrolytically stable. We discovered that the boronic esters derived from (1,1′-bicyclohexyl)-1,1′-diol are the most stable among those examined.
The ionic complex [PtCl(3)(C(2)H(4))](-)[(S,S)-(PhMeCH)(2)NH(2)](+) containing a chiral secondary amine is a new and versatile chiral derivatizing agent (CDA) for the determination of the enantiomeric composition of several unsaturated compounds including simple olefins: the diastereoisomeric mixtures arising from the exchange of ethylene by the unsaturated analytes are easily detected by (195)Pt NMR spectroscopy.
Ionic complexes [PtCl3(C2H4)]-[AmH]+, containing chiral secondary amines, constitute a versatile class of chiral derivatizing agents (CDAs) for the enantiomeric purity determination of chiral unsaturated compounds via 195Pt NMR spectroscopy. The NMR conformational analysis allows us to search for the stereochemical basis of their enhanced versatility.
The use of organometallic CDAs based on ethene-platinum(II) complexes, covalent cis- and trans-dichloro(Am)(ethylene)platinum(II), and ionic [PtCl(3)(C(2)H(4))](-)[AmH](+), containing primary and secondary amines, for the (195)Pt NMR enantiodiscrimination of chiral unsaturated compounds is reviewed.
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