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A visible‐light organophotocatalytic [2+2] cycloaddition of electron‐deficient styrenes is described. Photocatalytic [2+2] cycloadditions are typically performed with electron‐rich styrene derivatives or α,β‐unsaturated carbonyl compounds, and with transition‐metal‐based catalysts. We have discovered that an organic cyanoarene photocatalyst is able to deliver high‐value cyclobutane products bearing electron‐deficient aryl substituents in good yields. A range of electron‐deficient substituents are tolerated, and both homodimerisations and intramolecular [2+2] cycloadditions to fused bicyclic systems are available by using this methodology. [ABSTRACT FROM AUTHOR]

Saturated bioisosteres of substituted benzenes offer opportunities to fine-tune the properties of drug candidates in development. Bioisosteres of para -benzenes, such as those based on bicyclo[1.1.1]pentane, are now very common and can be used to increase aqueous solubility and improve metabolic stability, among other benefits. Bioisosteres of ortho - and meta -benzenes were for a long time severely underdeveloped by comparison. This has begun to change in recent years, with a number of potential systems being reported that can act as bioisosteres for these important fragments. In this review, we will discuss these recent developments, summarizing the synthetic approaches to the different bioisosteres as well as the impact they have on the physiochemical and biological properties of pharmaceuticals and agrochemicals., (Copyright © 2024, Diepers and Walker.)

A visible-light organophotocatalytic [2+2] cycloaddition of electron-deficient styrenes is described. Photocatalytic [2+2] cycloadditions are typically performed with electron-rich styrene derivatives or α,β-unsaturated carbonyl compounds, and with transition-metal-based catalysts. We have discovered that an organic cyanoarene photocatalyst is able to deliver high-value cyclobutane products bearing electron-deficient aryl substituents in good yields. A range of electron-deficient substituents are tolerated, and both homodimerisations and intramolecular [2+2] cycloadditions to fused bicyclic systems are available by using this methodology., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The design and gram-scale synthesis of a cyclohexa-1,4-diene-based surrogate of isobutene gas is reported. Using the highly electron-deficient Lewis acid B(C 6 F 5 ) 3 , application of this surrogate in the hydromethallylation of electron-rich styrene derivatives provided sterically congested quaternary carbon centers. The reaction proceeds by C(sp 3 )-C(sp 3 ) bond formation at a tertiary carbenium ion that is generated by alkene protonation. The possibility of two concurrent mechanisms is proposed on the basis of mechanistic experiments using a deuterated surrogate., (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

A photochemical approach to polysubstituted heterocycles using UV-induced alkene isomerization is described. The method allows for the synthesis of disubstituted furans and pyrroles under mild and neutral conditions and also provides access to a class of trisubstituted furans pertinent to natural-product synthesis. The method has broad functional-group tolerance and many richly decorated heterocycles have been prepared incorporating functional groups that are unstable under Brønsted and Lewis acidic conditions., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A regioselective hydrodeuteration of alkenes using monodeuterated cyclohexa-1,4-dienes as surrogates for hydrogen deuteride (HD) gas is reported. The metal-free process proceeds under B(C 6 F 5 ) 3 catalysis presumably by deuteride abstraction to form borodeuteride [DB(C 6 F 5 ) 3 ] - and highly Brønsted-acidic Wheland intermediates. Low catalyst loadings (2.5 mol %) are used, and the reaction proceeds at room temperature.

A short (10 step) and efficient (15% overall yield) synthesis of the natural product (-)-(3 R)-inthomycin C is reported. The key steps comprise three C-C bond-forming reactions: (i) a vinylogous Mukaiyama aldol, (ii) an olefin cross-metathesis reaction, and (iii) an asymmetric Mukaiyama-Kiyooka aldol. This route is notable for its brevity and has the advantage of lacking stoichiometric tin-promoted cross-coupling reactions present in previous approaches. Initial investigations on the biological activity of (-)-(3 R)-inthomycin C and structural analogues on human cancer cell lines are also described for the first time.