Recent visible light and metal free strategies in [2+2] and [4+2] photocycloadditions

When aiming to synthesize molecules with elevated molecular complexity starting from relatively simple starting materials, photochemical transformations represent an open avenue to circumvent analogous multistep procedures. Specifically, light-mediated cycloadditions remain as powerful tools to generate new bonds begotten from non-very intuitive disconnections, that alternative thermal protocols would not offer. In response to the current trend in both industrial and academic research pointing towards green and sustainable processes, several strategies that meet these requirements are currently available in the literature. This Minireview summarizes [2+2] and [4+2] photocycloadditions that do not require the use of metal photocatalysts by means of alternative strategies. It is segmented according to the cycloaddition type in order to give the reader a friendly approach and we primarily focus on the most recent developments in the field carried out using visible light, a general overview of the mechanism in each case is offered as wellFinancial support was provided by the European Research Council (ERC-CoG, Contract Number: 647550), the Spanish Government (RTI2018-095038-B-I00), the ‘Comunidad de Madrid’ and European Structural Funds (S2018/NMT-4367). R. I. R thanks Fundación Carolina for a graduate fellowshi

Di- and triphenylated cation radical polymers and their use as Diels-Alder catalysts

A regenerative catalyst composition is provided comprising polymer supported covalently bound di- or triphenylated cation radical salts, wherein the cation radical is a Group VA element and the complementing anion is a Lewis acid anion or other anion, such as perhalo acid or acid metal halide. The phenylated cation radical salts, either polymer supported or unsupported, are useful catalytic agents facilitating the versatile Diels-Alder organic synthetic reactions to form cyclohexene compounds including the more intricate terpenoids, steroids, alkaloids, and prostaglandinoids.Board of Regents, University of Texas Syste

Di- and triphenylated cation radical polymers and their use as Diels-Alder catalysts

A regenerative catalyst composition is provided comprising polymer supported covalently bound di- or triphenylated cation radical salts, wherein the cation radical is a Group VA element and the complementing anion is a Lewis acid anion or other anion, such as perhalo acid or acid metal halide. The phenylated cation radical salts, either polymer supported or unsupported, are useful catalytic agents facilitating the versatile Diels-Alder organic synthetic reactions to form cyclohexene compounds including the more intricate terpenoids, steroids, alkaloids, and prostaglandinoids.Board of Regents, University of Texas Syste