Visible Light‐Mediated Manipulation of 1,n‐Enynes in Organic Synthesis

Abstract

The 1,n-enynes are potent scaffolds in organic synthesis, providing a state-of-the-art approach for synthesizing various acyclic and carbo-and heterocyclic compounds. Radical cascade cyclization and CÀ H functionalization of 1,n-enynes have gained immense attention in the synthetic community. Significant advancement in this field has been developed over the years, employing harsh and expensive metal catalysts usually associated with intense product purification and unwanted side-products. In this context, the advent of visible light photocatalysis as a mild and efficient approach in the area of 1,nenynes is a welcome step. Herein, we provide an exclusive overview of the recent developments in visible light-assisted manipulation of 1,n-enynes. We have classified the review into 1,3-, 1,4-, 1,5-, 1,6-, 1,7-, and 1,8-enynes, as well as dienyne, and enediyne-based reactions.

Visible light-driven highly atom-economical divergent synthesis of substituted fluorenols and cyclopropylcarbaldehydes

“…13 c However, the abovementioned methods often suffer from harsh reaction conditions, environmentally unfriendly protocols, a mixture of regioisomers or a limited substrate scope, very low atom economy, and the generation of by-products. To address these challenges, our and other research groups rationally designed several protocols for enyne precursors bearing different groups, 14,15 which are more readily accessible than the acyclic substrates required in conventional methods. Notably, achieving sequential introduction of two most valuable functionalities in a single cascade reaction in one step while enhancing molecular complexity using simple and easily accessible feedstocks, ideally with 100% atom economy, under mild conditions that ensure user-friendly operation represents a highly desirable yet challenging task in synthetic chemistry.…”

Visible-Light-Initiated Catalyst-Free Radical Annulation Reactions of 1,6-Enynes and Aryl Sulfonyl Bromide to Assemble Sulfonation/Bromination Succinimide Derivatives

“…The radical addition and cyclization of 1, n -enynes represent a powerful and efficient strategy for the synthesis of structural diversity organic compounds . However, in many reported 1, n -enyne radical reactions, only one atom or group was inserted into the final products .…”

CO2-facilitated radical sequential (3 + 2) annulation of 1,6-enynes via cooperation of sulfinate catalysis and photocatalysis

“…Therefore, it's desirable and essential to develop an environmentally friendly and mild method for the direct preparation of tetrahydrofluorenes. As visible-light-driven photoredox catalysis is an eco-friendly method for organic synthesis, 17 we envisioned a photocatalytic strategy to enable intramolecular radical sequential (3 + 2) annulation of 1,6-enynes, which are easy to prepare 18 to construct a broad spectrum of tetrahydrofluorenes and thus to present a practical green synthetic method for tetrahydrofluorenes (Scheme 1c). However, without preinstallation of activated chemical handles to 1,6-enynes, our proposed (3 + 2) annulation strategy which involves dearomatization and rearomatization of stable arene moieties under redox-neutral conditions is highly challenging.…”