Welwitindolinone C synthetic studies. Construction of the welwitindolinone carbon skeleton via a transannular nitrone cycloaddition.

Described is the construction of the N-methylwelwitindolinone C core via an efficient strategy that employs a sequential rhodium carbenoid-mediated O-H insertion, Claisen rearrangement and transannular [3+2] nitrone cycloaddition.

VEGF receptor kinase inhibitors: phthalazines, anthranilamides and related structures.

Inhibition of vascular endothelial growth factor receptor (VEGFR) signalling, using either antibodies or small molecule inhibitors of the VEGFR kinase domain, has become a major area of research in oncology. The phthalazine PTK787/ZK222584, first published in the literature in 1998, is one of the most advanced VEGFR inhibitors in the clinic. This paper provides an update on the patenting activity related to the phthalazine class. In addition, newer kinase inhibitor pharmacophores derived from this class (e.g., anthranilamides) will be reviewed.

Tandem Inter [4 + 2]/Intra [3 + 2] Cycloadditions of Nitroalkenes. The Bridged Mode (beta-Tether).

A new variation of the tandem inter [4 + 2]/intra [3 + 2] cycloaddition of nitroalkenes has been developed. This method involves the Lewis acid-promoted [4 + 2] cycloaddition of nitro olefins 12 with 1-alkoxy-1,4-dienes 3. The resulting nitronates 13, bearing a C(5) tethered dipolarophile, undergo thermal, intramolecular [3 + 2] cycloaddition to afford stable tricyclic nitroso acetals 14, which can be subsequently reduced to unveil a new carbocycle 16. Thus, in three steps, highly functionalized aminocyclopentanes can be stereoselectively constructed in high yield.

Tandem Inter [4 + 2]/Intra [3 + 2] Cycloadditions of Nitroalkenes. Asymmetric Synthesis of Highly Functionalized Aminocyclopentanes Using the Bridged Mode (beta-Tether) Process.

An asymmetric, tandem inter [4 + 2]/intra [3 + 2] bridged mode (beta-tether) cycloaddition of nitroalkenes has been developed. This new sequence involves the Lewis acid-promoted [4 + 2] cycloaddition of nitro olefins with enantiopure 1-alkoxy-1,4-dienes. The resulting nitronates, bearing a C(5) tethered dipolarophile, undergo thermal, intramolecular [3 + 2] cycloaddition to afford stable tricyclic nitroso acetals, which can be subsequently reduced to provide interesting aminocyclopentanes. Thus, in three steps, highly functionalized, enantiomerically enriched aminocyclopentanes can be constructed with good yield and high ee. Additionally, the Lewis acid was found to impart a remarkable influence on the stereochemical outcome of the [4 + 2] cycloaddition.