Synthesis and cellular uptake of carbamoylated mannose derivatives.

A series of 3-carbamoyl- and 2,3-dicarbamoyl-mannose derivatives were synthesized, conjugated to a fluorescent dye (Cy5GE, AF 647 or NBD) and their cellular uptake in A549 and THP-1 cell lines was studied by FACS. In contrast to earlier studies on carbamoyl mannosides, the observed uptake was not related to carbamoyl group on the mannose residue but rather to the cyanine dye attached, a trend previously observed for Cy5-fructose conjugates. The NBD-conjugates however, showed a temperature and concentration dependent uptake in case of mannose conjugates. These results suggest a profound impact of the dye which should be taken into consideration when studying the uptake of small molecules by dye conjugation.

Rational Design of 5-(4-(Isopropylsulfonyl)phenyl)-3-(3-(4-((methylamino)methyl)phenyl)isoxazol-5-yl)pyrazin-2-amine (VX-970, M6620): Optimization of Intra- and Intermolecular Polar Interactions of a New Ataxia Telangiectasia Mutated and Rad3-Related (ATR) Kinase Inhibitor.

The DNA damage response (DDR) is a DNA damage surveillance and repair mechanism that can limit the effectiveness of radiotherapy and DNA-damaging chemotherapy, commonly used treatment modalities in cancer. Two related kinases, ataxia telangiectasia mutated (ATM) and ATM and Rad3-related kinase (ATR), work together as apical proteins in the DDR to maintain genome stability and cell survival in the face of potentially lethal forms of DNA damage. However, compromised ATM signaling is a common characteristic of tumor cells, which places greater reliance on ATR to mediate the DDR. In such circumstances, ATR inhibition has been shown to enhance the toxicity of DNA damaging chemotherapy to many cancer cells in multiple preclinical studies, while healthy tissue with functional ATM can tolerate ATR inhibition. ATR therefore represents a very attractive anticancer target. Herein we describe the discovery of VX-970/M6620, the first ATR inhibitor to enter clinical studies, which is based on a 2-aminopyrazine core first reported by Charrier ( J. Med. Chem. 2011 , 54 , 2320 - 2330 , DOI: 10.1021/jm101488z ).

Some limitations of an approach to the assembly of bryostatins by ring-closing metathesis.

Preliminary studies into the use of ring-closing metathesis (RCM) in a convergent approach for the total synthesis of bryostatins are described. An ester that would have provided an advanced intermediate for a synthesis of a 20-deoxybryostatin by a RCM was prepared from an unsaturated acid and alcohol corresponding to the C1-C16 and C17-C27 fragments. However, studies of the formation of the C16-C17 double-bond by RCM were not successful and complex mixtures of products were obtained. To provide an insight into factors that may be involved in hindering RCM in this system, a slightly simplified C1-C16 acid and modified C17-C25 alcohols were prepared and their use for the synthesis of analogues of bryostatins was investigated. Although only low yields were obtained, it appeared that macrolides analogous to the bryostatins can be prepared by RCM, using the Grubbs II catalyst, if the precursors lack the two methyl groups at C18. RCM was not observed, however, for substrates in which these methyl groups were present.

Effective 1,5-, 1,6- and 1,7-remote stereocontrol in reactions of alkoxy- and hydroxy-substituted allylstannanes with aldehydes.

Alk-2-enylstannanes with 4-, 5- and 6-alkoxy- or -hydroxy-substituents are transmetallated stereoselectively with tin(iv) halides to generate allyltin trihalides which react with aldehydes to give (Z)-alk-3-enols with useful levels of 1,5-, 1,6- and 1,7-stereocontrol. Alk-2-enylstannanes with a stereogenic centre bearing a hydroxy or alkoxy group at the 4-, 5- or 6-position, react with overall (Z)-1,5-, 1,6- and 1,7-syn-stereoselectivity with respect to the hydroxy and alkoxy substituents. The analogous reactions of alkoxy- and -hydroxyalk-2-enylstannanes with a methyl bearing stereogenic centre at the 4- or 5-position react with overall (Z)-1,5- and 1,6-anti-stereoselectivity with respect to the hydroxy and methyl substituents.

Selective killing of ATM- or p53-deficient cancer cells through inhibition of ATR.

Here we report a comprehensive biological characterization of a potent and selective small-molecule inhibitor of the DNA damage response (DDR) kinase ATR. We show a profound synthetic lethal interaction between ATR and the ATM-p53 tumor suppressor pathway in cells treated with DNA-damaging agents and establish ATR inhibition as a way to transform the outcome for patients with cancer treated with ionizing radiation or genotoxic drugs.

Discovery of potent and selective inhibitors of ataxia telangiectasia mutated and Rad3 related (ATR) protein kinase as potential anticancer agents.

DNA-damaging agents are among the most frequently used anticancer drugs. However, they provide only modest benefit in most cancers. This may be attributed to a genome maintenance network, the DNA damage response (DDR), that recognizes and repairs damaged DNA. ATR is a major regulator of the DDR and an attractive anticancer target. Herein, we describe the discovery of a series of aminopyrazines with potent and selective ATR inhibition. Compound 45 inhibits ATR with a K(i) of 6 nM, shows >600-fold selectivity over related kinases ATM or DNA-PK, and blocks ATR signaling in cells with an IC(50) of 0.42 µM. Using this compound, we show that ATR inhibition markedly enhances death induced by DNA-damaging agents in certain cancers but not normal cells. This differential response between cancer and normal cells highlights the great potential for ATR inhibition as a novel mechanism to dramatically increase the efficacy of many established drugs and ionizing radiation.