6-Ethynylthieno[3,2-d]- and 6-ethynylthieno[2,3-d]pyrimidin-4-anilines as tunable covalent modifiers of ErbB kinases.

Analysis of the x-ray crystal structure of mono-substituted acetylenic thienopyrimidine 6 complexed with the ErbB family enzyme ErbB-4 revealed a covalent bond between the terminal carbon of the acetylene moiety and the sulfhydryl group of Cys-803 at the solvent interface. The identification of this covalent adduct suggested that acetylenic thienopyrimidine 6 and related analogs might also be capable of forming an analogous covalent adduct with EGFR, which has a conserved cysteine (797) near the ATP binding pocket. To test this hypothesis, we treated a truncated, catalytically competent form of EGFR (678-1020) with a structurally related propargylic amine (8). An investigation of the resulting complex by mass spectrometry revealed the formation of a covalent complex of thienopyrimidine 8 with Cys-797 of EGFR. This finding enabled us to readily assess the irreversibility of various inhibitors and also facilitated a structure-activity relationship understanding of the covalent modifying potential and biological activity of a series of acetylenic thienopyrimidine compounds with potent antitumor activity. Several ErbB family enzyme and cell potent 6-ethynyl thienopyrimidine kinase inhibitors were found to form covalent adducts with EGFR.

Discovery of thiophene inhibitors of polo-like kinase.

The discovery and development of a series of thiophenes as potent and selective inhibitors of PLK is described. Identification and characterization of 2, a useful in vitro PLK inhibitor tool compound, is also presented.

Synthesis and evaluation of aniline headgroups for alkynyl thienopyrimidine dual EGFR/ErbB-2 kinase inhibitors.

Aniline 'headgroups' were synthesized and incorporated into an alkynyl thienopyrimidine series of EGFR and ErbB-2 inhibitors. Potent inhibition of enzyme activity and cellular proliferation was observed. In certain instances, protein binding was reduced and oral exposure was found to be somewhat improved relative to compounds containing the reference aniline.

Synthesis and stereochemical effects of pyrrolidinyl-acetylenic thieno[3,2-d]pyrimidines as EGFR and ErbB-2 inhibitors.

A novel class of pyrrolidinyl-acetyleneic thieno[3,2-d]pyrimidines has been identified which potently inhibit the EGFR and ErbB-2 receptor tyrosine kinases. Synthetic modifications of the pyrrolidine carbamate moiety result in a range of effects on enzyme and cellular potency. In addition, the impact of the absolute stereochemical configuration on cellular potency and oral mouse pharmacokinetics is described.

Design of potent thiophene inhibitors of polo-like kinase 1 with improved solubility and reduced protein binding.

A series of thiophene PLK1 inhibitors was optimized for increased solubility and reduced protein binding through the appendage of basic amine functionality. Interesting selectivity between PLK1 and PLK3 was also obtained through these modifications.