The first total syntheses of (+)-zampanolide (1) and (+)-dactylolide (2), members of a new class of tumor cell growth inhibitory macrolides, have been achieved. Key features of the unified synthetic scheme included the stereocontrolled construction of the cis-2,6-disubstituted tetrahydropyran via a modified Petasis-Ferrier rearrangement, a highly convergent assembly of the macrocyclic domain, and, in the case of zampanolide, a Curtius rearrangement/acylation tactic to install the N-acyl hemiaminal. The complete relative and absolute stereochemistries for both (+)-zampanolide and (+)-dactylolide were also assigned, albeit tentatively in the case of (+)-zampanolide (1).
Overexpression of AKT has an antiapoptotic effect in many cell types, and expression of dominant negative AKT blocks the ability of a variety of growth factors to promote survival. Therefore, inhibitors of AKT kinase activity might be useful as monotherapy for the treatment of tumors with activated AKT. Herein, we describe our lead optimization studies culminating in the discovery of compound 3g (GSK690693). Compound 3g is a novel ATP competitive, pan-AKT kinase inhibitor with IC 50 values of 2, 13, and 9 nM against AKT1, 2, and 3, respectively. An X-ray cocrystal structure was solved with 3g and the kinase domain of AKT2, confirming that 3g bound in the ATP binding pocket. Compound 3g potently inhibits intracellular AKT activity as measured by the inhibition of the phosphorylation levels of GSK3beta. Intraperitoneal administration of 3g in immunocompromised mice results in the inhibition of GSK3beta phosphorylation and tumor growth in human breast carcinoma (BT474) xenografts.
There is substantial interest in dyads in which C(60) is covalently linked to electron donors, such as porphyrins, which absorb light strongly in the visible region. We present here the details of the syntheses of such compounds, which can be broadly organized into categories depending upon the nature of the linker joining the two chromophores. The structural aspects of intramolecular electronic interaction that we have sought to explore have dictated the synthetic strategies employed to generate these classes of molecules. Flexible glycol linkers were used to allow close approach between the fullerene and porphyrin, facilitating through-space interactions. These linkers also allowed studies of the effects of metal cation complexation. Naphthalene and alkyne linkers were used to examine the possible effects a conjugated or aromatic linker might have on photophysical properties. Finally, steroids were used as linkers in dyads expected to possess a large distance between the two chromophores, in which only through-bond interactions between the fullerene and porphyrin should be possible.
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