SummaryIn the presence of an alkene, three different modes of photocycloaddition with benzene derivatives can occur; the [2 + 2] or ortho, the [3 + 2] or meta, and the [4 + 2] or para photocycloaddition. This short review aims to demonstrate the synthetic power of these photocycloadditions.

In the present work, we report on a new intramolecular para-cycloaddition of arenes with allenes

Signal transducer and activator of transcription 3 (STAT3) is a component of the JAK/STAT pathway. Therapeutic inhibition of STAT3 has been of high interest, as its aberrant activation has been linked to cancer, inflammation, and other human diseases. The withanolide family natural product withaferin A (1) inhibits STAT3 activation. We designed, synthesized, and evaluated simplified withanolide analogues SLW1 (3) and SLW2 (4), and found that SLW1 retained the STAT3 inhibitory activity of withaferin A.

The photocycloaddition of alkenes with aromatic systems may proceed through three reaction modes, affording different types of products: ortho, meta, and para. These reactions generate a considerable increase in complexity, and yield products arduously attainable by classical synthetic steps. Whereas the meta-photocycloaddition has gained a lot of attention in the last decades because of its applicability in the total synthesis of numerous natural products, the ortho- and para-cycloadditions still have a great potential for further development. In this highlight, we review the latest advances in the field of photocycloaddition of alkenes to aromatic systems.

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Organic chemistry Z 0200 Recent Developments in Arene Photocycloadditions -[27 refs.]. -(STREIT, U.; BOCHET, C. G.; Chimia 62 (2008) 12, 962-966; Dep. Chem., Univ. Fribourg, CH-1700 Fribourg, Switz.; Eng.) -Lindner 42-256