Efficient Functionalization of Organosulfones via Photoredox Catalysis: Direct Incorporation of α-Carbonyl Alkyl Side Chains into α-Allyl-ß-Ketosulfones.

A novel and efficient method for functionalizing organosulfones has been established, utilizing a visible-light-driven intermolecular radical cascade cyclization of α-allyl-ß-ketosulfones. This process employs fac-Ir(ppy)3 as the photoredox catalyst and α-carbonyl alkyl bromide as the oxidizing agent. Via this approach, the substrates experience intermolecular addition of α-carbonyl alkyl radicals to the alkene bonds, initiating a sequence of C-C bond formations that culminate in the production of organosulfone derivatives. Notably, this technique features gentle reaction conditions and an exceptional compatibility with a wide array of functional groups, making it a versatile and valuable addition to the field of organic synthesis.

Streamlined Synthesis of Varied Heteroarene-Condensed Benzofuran Derivatives via [4 + 2] Annulation of Benzofuran-Derived Azadienes and N-Alkyl Quinolinium Salts.

Herein we have pioneered an innovative synthetic strategy for the efficient assembly of various heteroarene-condensed benzofuran derivatives, utilizing benzofuran-derived azadienes (BDAs) and quinolines as the starting materials. This method functions with transition-metal catalysis and uses cost-effective formic acid as the reducing agent. Mechanistic investigations indicate that this transformation would involve a [4 + 2] annulation cascade process. This approach demonstrates a high tolerance to various functional groups and yields excellent results.

Copper-catalyzed one-pot [3 + 2] cycloadditions of ethynyl indoloxazolidones with 1,3-cyclohexanediones.

Fused furans are commonly found units in natural products and medicinal molecules, and methods for their introduction are of fundamental importance. Here we report one-pot cycloadditions of ethynyl indoloxazolidones with 1,3-cyclohexanediones enabled by copper catalysis, leading to a series of functionalized furan derivatives in good yields. This method features mild reaction conditions, high efficiency, and wide substrate scope.

Brønsted acid-mediated tandem cyclization of triarylphosphines and in situ generated ortho-alkynyl quinone methides: access to heterocyclic quaternary phosphonium salts.

Heterocyclic Quaternary Phosphonium Salts (HQPS) have emerged as promising chemicals for organic synthesis and medicinal chemistry. However, the present synthetic methodology of this type of compound is still limited. Here, we report a deconstructive reorganization strategy based on Brønsted acid-mediated tandem 1,4 addition/intramolecular cyclization of triphenylphosphine derivatives and in situ generated o-AQMs for the first time. This protocol provides a novel approach to heterocyclic quaternary phosphonium salts. The method also features a non-metal catalyst, mild reaction conditions, high efficiency and wide substrate scope. Moreover, a series of obtained heterocyclic phosphonium salts can be converted to isotopically labelled 2-benzofuran compounds directly by simple deuteration reactions.