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Photopharmacological tools enable the precise spatiotemporal control of small molecule drugs. Amongst them, caged compounds incorporate a photolabile moiety which is released under illumination, thus liberating the active molecule. Caging groups have long been known and many chemical scaffolds have already been used in different applications. However, most of the initial examples are cleaved with UV light, which suffers from low tissue permeability and cell damage. Recently, caging groups that are released under visible light have been reported, which expand their utility. In this review, we outline the chemical strategies that have been used to increase the absorption wavelengths; we compare their photophysical properties, discuss their synthetic accessibility, and exemplify some of their biological applications. [ABSTRACT FROM AUTHOR]

Weinreb amide derivatives of tetramates may be effectively accessed by chemoselective Dieckmann reaction, and further react with Grignards in a fully chemoselective reaction, giving rise to unsaturated acyl derivatives not easily available by other routes. These systems are strong chelators of calcium, and some show potent activity against Gram positive bacteria, and one is a first-in-class proteasome inhibitor. [ABSTRACT FROM AUTHOR]

A ring-closing alkene metathesis (RCM)/ oxyselenation-selenoxide elimination sequence was established to the sodium salts E- and Z- 25 of the originally proposed structure for the recently isolated cytotoxin aruncin B ( 1), as well as to the sodium salt Z- 34 of a related ethyl ether regioisomer; however, none of their corresponding free acids could be obtained. Their acid sensitivity, together with detailed analysis of the spectroscopic data indicated that profound structural revision was necessary. This led to reassignment of aruncin B as a Z-γ-alkylidenebutenolide Z- 36. Although a related RCM/ oxyselenation-selenoxide elimination sequence was used to confirm the γ-alkylidenebutenolide motif, a β-iodo Morita-Baylis-Hillman reaction/ Sonogashira cross-coupling-5- exo-dig lactonisation sequence was subsequently developed, due to its brevity and flexibility for diversification. Aruncin B ( 36), together with 14 γ-alkylidenebutenolide analogues, were generated for biological evaluation. [ABSTRACT FROM AUTHOR]