Avoidance of apoptosis is critical for the development and sustained growth of tumours. The pro-survival protein myeloid cell leukemia 1 (MCL1) is overexpressed in many cancers, but the development of small molecules targeting this protein that are amenable for clinical testing has been challenging. Here we describe S63845, a small molecule that specifically binds with high affinity to the BH3-binding groove of MCL1. Our mechanistic studies demonstrate that S63845 potently kills MCL1-dependent cancer cells, including multiple myeloma, leukaemia and lymphoma cells, by activating the BAX/BAK-dependent mitochondrial apoptotic pathway. In vivo, S63845 shows potent anti-tumour activity with an acceptable safety margin as a single agent in several cancers. Moreover, MCL1 inhibition, either alone or in combination with other anti-cancer drugs, proved effective against several solid cancer-derived cell lines. These results point towards MCL1 as a target for the treatment of a wide range of tumours.

Myeloid cell leukemia 1 (Mcl-1), an antiapoptotic member of the Bcl-2 family of proteins, whose upregulation when observed in human cancers is associated with high tumor grade, poor survival, and resistance to chemotherapy, has emerged as an attractive target for cancer therapy. Here, we report the discovery of selective small molecule inhibitors of Mcl-1 that inhibit cellular activity. Fragment screening identified thienopyrimidine amino acids as promising but nonselective hits that were optimized using nuclear magnetic resonance and X-ray-derived structural information. The introduction of hindered rotation along a biaryl axis has conferred high selectivity to the compounds, and cellular activity was brought on scale by offsetting the negative charge of the anchoring carboxylate group. The obtained compounds described here exhibit nanomolar binding affinity and mechanismbased cellular efficacy, caspase induction, and growth inhibition. These early research efforts illustrate drug discovery optimization from thienopyrimidine hits to a lead compound, the chemical series leading to the identification of our more advanced compounds S63845 and S64315.

Molybdenum- and tungsten-based olefin metathesis catalysts have demonstrated excellent results in the control of cis (Z-) selectivity as well as enantioselectivity. However, their air and moisture sensitivity, which requires the use of a glovebox, has prevented their more widespread use by organic chemists. Now we report on developed, preweighed Mo catalysts formulated in paraffin tablets. The significantly improved air stability, high homogeneity, and uniformity of the pellets allow researchers to carry out reactions on the bench avoiding the need of a glovebox. The two different Mo-based complexes which were packed into tablets are XiMoPac-Mo001 (1) that can be used to achieve endo-selective enyne ring-closing metathesis (RCM) reactions, inter alia; and XiMoPac-Mo003 (2) which was reported among the best catalysts to promote Z-selective cross-metathesis. For the evaluation of the wax-protected catalysts commonly used, highly reproducible robust model reactions were chosen: homo cross-metathesis (HCM) of functionalized (e.g., methyl 9-decenoate) and unfunctionalized (allylbenzene) terminal olefins, and ring closing metathesis (RCM) of diethyl diallylmalonate. The yields and conversions were comparable with those which can be achieved in glovebox with nonformulated catalysts. Exposure to air did not cause any significant reduction in conversion while the product selectivity (targeted product vs homologues derived from double bond isomerization) remained high. In contrast, exposure to air caused a measurable drop in the conversion with the nonprotected catalyst. Furthermore, the formulated catalysts remained unaffected even after 4 h of exposure to air, showing its enhanced air stability. In conclusion, these commercially available air-stable Mo-catalyst tablets allow the reactions to be accomplished using ordinary Schlenk techniques, and hence simplify catalyst handling in pilot laboratories and plants.

Keywords: Functionalization / Halogen/metal permutation / Metalation / Nucleophilic addition / Pyrimidines / Single electron transfer / Trifluoromethyl groups 5-Pyrimidyllithium species are fairly stable when the metal is flanked by two electron-withdrawing substituents such as trifluoromethyl and chlorine or bromine. Thus, the corresponding 5-carboxylic acids are produced in high yields from 4,5-dibromo-6-(trifluoromethyl)pyrimidine and 5-bromo-4-chloro-6-(trifluoromethyl)pyrimidine upon halogen/metal permutation accomplished with isopropylmagnesium chloride or butyllithium followed by carboxylation. Satisfactory or excellent yields of 5-carboxylic acids are equally obtained when 4-chloro-, 2,4-dichloro-and 2,4-dibromo-6-(trifluoromethyl)pyrimidine are deprotonated with lithium diisopro-

An expedient route to all three monobrominated and all three dibrominated isomers of 4‐(trifluoromethyl)pyrimidine, and to several other halogenated pyrimidines, is described. Key steps are the electrophilic introduction of the halogen in the 5‐position of 2‐ or 4‐pyrimidinones, the bromodeoxygenation of pyrimidinones or thiopyrimidinones using phosphorus tribromide, and the partial debromination of dibromo‐4‐(trifluoromethyl)pyrimidines. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)