Visible Light-Induced Decomposition of Acyl Peroxides Using Isocyanides: Synthesis of Heteroarenes by Radical Cascade Cyclization

Abstract

Visible light-mediated facile synthesis of heteroarenes, namely, isoquinolines, benzothiazoles, and quinazolines, is demonstrated by employing isocyanides and inexpensive acyl peroxides. It is shown for the first time that singlet-excited isocyanides decompose acyl peroxides into aryl/alkyl radicals. The latter attack isocyanides, yielding imidoyl radicals that subsequently cyclize to afford heteroarene products. The protocol involving radical cascade reactions obviates the requirement of any external photocatalyst, oxidant, additive, and base.

Mn(OAc)3-Promoted Sulfonation–ipso-Cyclization Cascade via the SO3– Radical: The Synthesis of Spirocyclic Sulfonates

“…We postulated that this product emerged through ipso-cyclization, C−C bond cleavage, and demethylation. To further showcase the practicality of our Mn−K 2 S 2 O 5 method in radical sulfonation cascade, we attempted the reaction with isocyanides 50 or aryl alkynoate. 51 The desired products were obtained smoothly in 70 and 25% yields, respectively (Scheme 11).…”

“…Solvents for column chromatography were of technical standard. Starting materials 1 , 5 , 7 , and 9 were prepared by literature-reported methods. ,,, Column chromatography was performed with a 200–300 mesh silica gel. A column with a higher surface area is recommended to prevent blocking by inorganic salts.…”

Sustainable Synthesis through Catalyst‐Free Photoinduced Cascaded Bond Formation

“…This method resulted in the synthesis of diverse heteroarenes, such as isoquinolines, benzothiazoles, and quinazolines. [73] Where, acyl peroxides was used for the generation of aryl or alkyl sources upon the irradiation of blue LED.…”

Visible Light Catalyzed Stannylation of Aryl Halides

“…Organic reactions occurring via aryl radicals have gained widespread applications in organic synthesis due to their ability to swiftly assemble complex organic molecules and materials. [1] In recent years, photochemistry has become the elective methods for the generation of such intermediates from a plethora of substituted arenes including arene diazonium salts, [2] aryl sulfonyl chlorides, [3] aroyl peroxides, [4] aryl silanes, [5] aryl selenonium salts, [6] aryl boronic acids, [7] diaryliodonium salts, [8] ammonium salts, [9] aryl hydrazines, [10] benzoic acids, [11] sulfonium salts [12] and arylazo sulfones. [13] Nonetheless, the adoption of aryl halides as cheap, accessible and storage-resistant precursors of aryl radicals remains the best choice, via photoinduced homolysis of the ArÀ X bond, [14] a XAT reaction, [15] under reductive photocatalyzed conditions [16] or the formation of an electron-donoracceptor (EDA) complex.…”