Synthesis and preliminary evaluation of 5,7-dimethyl-2-aryl-3H-pyrrolizin-3-ones as angiogenesis inhibitors

Sunitinib (Sutent®) is a receptor tyrosine kinase (RTK) and angiogenesis inhibitor approved for the treatment of renal cell carcinomas, gastrointestinal stromal tumours and pancreatic neuroendocrine tumours. A key structural motif retained throughout medicinal chemistry efforts during sunitinib\u27s development was the indoline-2-one group. In the search for new anti-angiogenic scaffolds, we previously reported that non-indoline-2-one-based derivatives of semaxanib (SU5416, a structurally simpler sunitinib predecessor that underwent Phase III trials) are active as angiogenesis inhibitors, indicating that the group is not essential for activity. This Letter describes the synthesis and structure-activity relationships of another class of non-indoline-2-one angiogenesis inhibitors related to sunitinib/semaxanib; the 5,7-dimethyl-2-aryl-3H-pyrrolizin-3-ones. A focussed library of 19 analogues was prepared using a simple novel process, wherein commercially available substituted arylacetic acids activated with an amide coupling reagent (HBTU) were reacted with the potassium salt of 3,5-dimethyl-1H-pyrrole-2-carbaldehyde in one-pot. Screening of the library using a cell-based endothelial tube formation assay identified 6 compounds with anti-angiogenesis activity. Two of the compounds were advanced to the more physiologically relevant rat aortic ring assay, where they showed similar inhibitory effects to semaxanib at 10 μg/mL, confirming that 5,7-dimethyl-2-aryl-3H-pyrrolizin-3-ones represent a new class of angiogenesis inhibitors

Unexpected synthesis of 3-imino-2-(pyrrol-2-yl) isatogen derivatives affords facile access to a 2-pyrrolyl isatogen

2-Aryl isatogens and their 3-imino derivatives have been extensively studied but to date there have been no reported variants carrying pyrrolyl substituents at the 2-position. This study describes the unexpected synthesis of two novel 3-imino-2-(pyrrol-2-yl) isatogen derivatives upon attempted amide couplings with (E)- or (Z)-3-(3,5-dimethyl-1H-pyrrol-2-yl)-2-(2-nitrophenyl)acrylic acids and p-phenylenediamines in the presence of uronium-based coupling reagents. Imine hydrolysis of one derivative under mild acid conditions afforded a 2-pyrrolyl isatogen in high yield. The compound showed potent in vitro antiplasmodial activity against Plasmodium falciparumN. Kirk and G. Sansom acknowledge financial support from the Australian Government for Australian Postgraduate Awards. P. Sudta and S. Suksamrarn acknowledge financial support from the Thailand Research Fund through the Royal Golden Jubilee PhD Program. M. Kelso acknowledges partial financial support from the University of Wollongong

Synthesis, structural characterisation, and preliminary evaluation of non-indolin-2-one-based angiogenesis inhibitors related to sunitinib (Sutent®)

The indolin-2-one fused-ring system and the 2,4-dimethylpyrrole unit represent key structural motifs in the anticancer drug sunitinib (Sutent®) and predecessor angiogenesis inhibitors that have undergone anticancer clinical trials (e.g. semaxanib, SU5416). In pursuit of novel anti-angiogenic scaffolds, we were interested in identifying whether the indolin-2-one group in these structures could be modified without losing activity. This paper describes novel condensation chemistry used to prepare a test series of (E)- and (Z)-alkenes related to SU5416 that retain the 2,4-dimethylpyrrole unit while incorporating ring-opened indolin-2-ones. Unique structural characteristics were identified in the compounds, such as intramolecular hydrogen bonds in the (Z)-alkenes, and several examples were shown to possess significant anti-angiogenic activity in a rat aorta in vitro model of angiogenesis. The work demonstrates that the indolin-2-one moiety is not an absolute requirement for angiogenesis inhibition in the sunitinib/SU5416 class

Synthesis, structural characterisation, and preliminary evaluation of non-indolin-2-one-based angiogenesis inhibitors related to sunitinib (Sutent®)

The indolin-2-one fused-ring system and the 2,4-dimethylpyrrole unit represent key structural motifs in the anticancer drug sunitinib (Sutent®) and predecessor angiogenesis inhibitors that have undergone anticancer clinical trials (e.g. semaxanib, SU541

Unexpected synthesis of 3-imino-2-(pyrrol-2-yl) isatogen derivatives affords facile access to a 2-pyrrolyl isatogen

<p>2-Aryl isatogens and their 3-imino derivatives have been extensively studied but to date there have been no reported variants carrying pyrrolyl substituents at the 2-position. This study describes the unexpected synthesis of two novel 3-imino-2-(pyrrol-2-yl) isatogen derivatives upon attempted amide couplings with (<i>E</i>)- or (<i>Z</i>)-3-(3,5-dimethyl-1<i>H</i>-pyrrol-2-yl)-2-(2-nitrophenyl)acrylic acids and <i>p</i>-phenylenediamines in the presence of uronium-based coupling reagents. Imine hydrolysis of one derivative under mild acid conditions afforded a 2-pyrrolyl isatogen in high yield. The compound showed potent in vitro antiplasmodial activity against <i>Plasmodium falciparum.</i></p