Epoxidation of Electron‐Deficient Alkenes Triggered by Visible‐Light‐Driven Phenol Photooxidation for the Synthesis of Epoxy Dienone Products

Abstract

This article describes a synthesis of epoxy dienone products starting from para‐substituted phenols bearing an electron‐deficient alkene at the meta position. This one‐pot photooxygenation/epoxidation transformation takes place at room temperature using catalytic amounts of Rose Bengal and cesium carbonate upon green light irradiation. This reaction provides access to a range of functionalized epoxy dienone products with diastereoisomeric ratios ranging from 4:1 to >12:1. DFT calculations and mechanistic experiments revealed that this reaction would proceed through singlet oxygen‐mediated photooxidation of phenols followed by an intramolecular oxygen atom transfer on the alkene side arm.

Lewis Acid-Catalyzed Tandem Reaction Strategy for the Synthesis of Dihydrophenalene-Fused Lactones

“…7-Hydroxy-1-naphthaldehyde ( S1 ) was prepared according to the literature procedures . 5-Hydroxy-2-methylbenzaldehyde ( S2 ) and 4-hydroxy-(1,1′-biphenyl)-2-carbaldehyde ( S3 ) were prepared according to the literature procedures. , At 0 °C in an ice bath, to a solution of KOH (2.24 g, 40.0 mmol, 4.0 equiv) in EtOH (20 mL) was slowly added 7-hydroxy-1-naphthaldehyde S1 , S2 , or S3 (10.0 mmol, 1.0 equiv). The resulting orange mixture was stirred at 0 °C in an ice bath for an additional 30 min.…”

Visible-light-mediated catalyst-free synthesis of trifluoromethyl(spiro)-epoxides bearing contiguous quaternary centers

“…There have been several continuous works in this field, which achieved the oxidation of alkenes under photocatalytic conditions. [52][53][54][55][56][57] Besides the use of olefins themselves to construct epoxides within such molecules, 58,59 visible-lightmediated intermolecular strategies to obtain epoxides have also been introduced. [60][61][62] For instance, diverse epoxides have been constructed from benzylic alcohols and styrene with oxygen as a green oxidant.…”

Unveiling dual catalysis enhancement of a pyridinium-containing Zn(ii) coordination polymer in aerobic photooxidation of organic substrates and selective photoreduction of CO2

“…[1][2][3][4] Among them, photooxidation of organic substrates and photoreduction of CO 2 have gained a lot of attention in the past decade, as these reactions not only provide a fundamental understanding of photocatalysis but also show promising practical applications. [5][6][7][8][9][10][11] For example, oxidative coupling of amines to imines, oxygenation of suldes to sulfoxides, oxidation of alcohols to carbonyl compounds, and dehydrogenation of Nheterocycles are several basic reactions in organic synthesis, which are also of signicant importance in the production of pharmaceuticals and ne chemicals. [12][13][14][15][16] Using light energy to drive these oxidation reactions is believed to be green, sustainable, and economical, especially with earth-abundant catalysts and molecular O 2 as an oxidant in air under mild conditions.…”