Copper-Catalyzed Aerobic S-Amination of Sulfenamides for the Synthesis of Sulfinamidines.

Herein, we present a copper-catalyzed oxidative amination of sulfenamides for the synthesis of sulfinamidines. By the employment of air as the terminal oxidant, a diverse array of secondary and primary amines can be efficiently transformed into their corresponding products. This method is well-suited for last-stage functionalization, and the underlying mechanism has been investigated. The transformation is characterized by exceptional chemoselectivity, mild conditions, facile operation, and broad substrate compatibility, which have significant implications for the fields of pharmaceuticals and organic synthesis.

Hypervalent Iodine Mediated Synthesis of Sulfinamidines from Sulfenamides.

In this study, we present a novel, efficient method for the oxidative amination of sulfenamides using diacetoxyiodobenzene (PhI(OAc)2) and amines under basic conditions. This innovative technique streamlines the synthesis of sulfinamidines under mild, metal-free conditions, achieving outstanding yields of up to 99%. Furthermore, we propose possible pathways that elucidate the observed molecular sequence of events in this reaction. This cutting-edge approach not only advances the synthesis of valuable sulfinamidine compounds but also expands the synthetic toolbox available to chemists, paving the way for future discoveries in organic synthesis and potential applications in medicinal chemistry.

Redox-Neutral Synthesis of Sulfilimines through the S-Alkylation of Sulfenamides.

In this work, we developed a metal-free and redox-neutral strategy for the selective S-alkylation of sulfenamides under basic conditions to yield sulfilimines. The key step involves the resonance between bivalent nitrogen-centered anions, generated after deprotonation of sulfenamides under alkaline conditions, and sulfinimidoyl anions. Our sustainable and efficient approach employs sulfur-selective alkylation of readily accessible sulfenamides and commercially available halogenated hydrocarbons, resulting in the successful synthesis of 60 sulfilimines in high yields (36-99%) and short reaction times.

Redox-Neutral Strategy for Sulfilimines Synthesis via S-Arylation of Sulfenamides.

In this investigation, an unprecedented transition-metal-free and redox-neutral synthesis of sulfilimines was realized through the S-arylation of readily obtainable sulfenamides employing diaryliodonium salts. The pivotal step encompassed the resonance between bivalent nitrogen-centered anions, engendered postdeprotonation of sulfenamides under alkaline conditions, and sulfinimidoyl anions. The experimental outcomes demonstrate that sulfinimidoyl anionic species function as efficacious nucleophilic reagents, affording sulfilimines with notable to exceptional yields and superlative chemoselectivity, all executed within a transition-metal-free protocol and under exceptionally mild conditions.

A highly efficient method to access unprotected C-3 bifunctional quaternary 3-allyl-3-(amino)oxindoles.

A highly efficient Rh(II) catalyzed non-radical protocol to access NH-free C-3 bifunctional oxindoles, which possess 3-allyl and 3-amino simultaneously, was first achieved by employing an intermolecular [2,3]-sigmatropic rearrangement reaction between diazooxindoles and tertiary allylic amines. Utilizing readily available allylamines as the nitrogen and allyl source concurrently, a wide range of bio-active 3-allyl-3-(amino)oxindoles were obtained in excellent yields under very mild reaction conditions; meanwhile, the TON can be up to 90 000. Our study addresses a gap in the literature by investigating intermolecular rearrangements of ammonium ylides with diazoamides, which have been relatively understudied.

Hypervalent Iodine-Mediated Synthesis of Sulfinimidate Esters from Sulfenamides.

In this study, we present a novel and efficient approach for the oxidative esterification of sulfenamides using phenyliodonium diacetate, enabling the synthesis of sulfinimidate esters and sulfilimines under mild and metal-free conditions, with yields reaching up to 99%. The protocol is readily scalable and compatible with a diverse range of substrates and functional groups, and we demonstrate its potential for late-stage functionalization of pharmacologically relevant molecules. Furthermore, we propose a plausible reaction mechanism to account for the observed sequence of events.

Rh(II)-catalyzed Doyle-Kirmse reaction: access to unprotected 3-allyl/3-allenyl-3-(thio)oxindoles.

The construction of the 3-allyl/3-allenyl-3-(thio)oxindole core remains a challenge in organic synthesis. Herein, we report a novel Rh2(esp)2 catalytic Doyle-Kirmse reaction to furnish the oxindole core, bearing unbiased NH as well as a quaternary stereogenic center at the 3-position, in good to excellent yields under mild conditions. These reactions are concise, practical, atom-economic, and highly efficient, and feature a TON of up to 3700. Moreover, a non-radical pathway was observed in this approach.

Cinchona Alkaloid Derived Iodide Catalyzed Enantioselective Oxidative α-Amination of Carbonyl Compounds toward the Construction of Spiroindolyloxindole.

Novel cinchona alkaloid derived iodide catalysts were developed for the enantioselective oxidative α-amination of 2-oxindoles, providing various functionalized spiropyrrolidine oxindoles in high yields and with good enantioselectivities. This iodide/ROOH catalytic system features a one-step synthesis of a catalyst with multiple functionalities, ease of operation, and good scalability, thereby enriching the repertoire of iodide catalysis for enantioselective oxidative coupling reactions.

Harnessing structurally unbiased ortho-benzoquinone monoimine for biomimetic oxidative [4+2] cycloaddition with enamines.

Reported herein is the first catalytic oxidative [4+2] cycloaddition of 2-aminophenols with cyclic enamines. This biomimetic catalytic oxidative strategy expediently accommodates the very labile structurally unbiased ortho-quinone monoimine intermediate for cycloaddition by controlling its formation rate, thus refraining from otherwise prerequisite steric or electronic stabilization and allowing efficient assembly of various tricyclic 1,4-benzoxazines in a step and atom economic fashion.

One-step assembly of alkoxypyrroloindolines via iodine-catalyzed alkoxycyclization of indole derivatives.

Herein we report an iodine-catalyzed alkoxycyclization of tryptamine derivatives under mild reaction conditions. This method distinguished itself by providing a catalytic, one-step assembly of diversely functionalized C3a-alkoxypyrroloindolines as well as dihydrofuran and lactone fused indolines. Mechanistic studies suggest that an ionic pathway is operative and this probably accounts for the diastereospecificity of all isolated cycloadducts.

Assembly of C3a-Peroxylated Pyrroloindolines via Interrupted Witkop Oxidation.

The first synthetically useful interrupted Witkop oxidation has been disclosed through a radical triggered oxidative peroxycyclization of tryptamine derivatives, using a TBAI/TBHP catalytic system. This differs from known tryptophan oxidations, which typically cleave the 2,3-double bond. Upon one-pot reduction, this system renders an easy access to structurally distinct peroxypyrroloindoles, which are demonstrated to be useful precursors in various downstream synthetic elaborations.

Bioinspired radical cyclization of tryptamines: synthesis of peroxypyrroloindolenines as potential anti-cancer agents.

Inspired by the heme iron-catalyzed radical insertion of dioxygen to the tryptophan indole ring, herein we utilize alkylperoxy radical species as a coupling partner to trigger a peroxycyclization of readily accessible tryptophan derivatives and enable the first synthesis of peroxypyrroloindolenines. A preliminary biological evaluation revealed promising anti-cancer activities (IC50 = 22.00 µM for compound 2a), and revealed that both the indolenine core and the peroxy functionality are responsible for the antiproliferation effect against Hela cell lines.