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An efficient and broadly applicable rhodium-catalyzed direct ortho-arylation of anilines with aryl iodides relying on readily available aminophosphines as traceless directing groups is reported. Its scope and functional group compatibility were both found to be quite broad as a large variety of both aminophosphines and (hetero)aryl iodides, including complex ones, could be utilized. The ortho-arylated anilines could be obtained in high average yields, without any competing diarylation and with full regioselectivity, which constitutes a major step forward compared to other processes. The reaction is moreover not limited to aryl iodides, as an aryl bromide and a triflate could be successfully used, and could be extended to diarylation. Mechanistic studies revealed the key and unique role of the aminophosphine, acting not only as a substrate but also as a ligand for the rhodium catalyst., SCOPUS: ar.j, info:eu-repo/semantics/published

De prime abord, l’introduction de ce document porte sur la chimie de l’iode hypervalent. La réactivité, la synthèse ainsi que des exemples d’applications synthétiques des composés d’iode(III) y sont présentés. Une section portant sur les sels d’iodonium y est aussi incluse. Ensuite, les antécédents du groupe ainsi que les travaux portant sur les contractions oxydantes de dihydropyranones en -butyrolactones sont présentés afin de mettre le projet de recherche initial en contexte. Les travaux de recherches de ce mémoire portaient initialement sur les contractions oxydantes promues par les réactifs d’iode(III) de dérivés de classe pyrone vers leur buténolide correspondant. Malheureusement, ce projet initial n’a jamais porté fruit, mais a mené vers la découverte d’une nouvelle classe de sels de type pyrone-iodonium. La réactivité de ces sels a été explorée à l’aide de réactions d’arylation, de couplage, d’addition d’aza-Michael et de lactamisation. Le chapitre 1 porte sur la synthèse d’une pyrone modèle pour ensuite effectuer des tests de contraction oxydante sur celle-ci. La variation de la nature du réactif d’iode(III), du solvant ainsi que de la température n’ont jamais mené à la formation du buténolide désiré. Le changement du substrat étudié n’a pas non plus fonctionné. Toutefois, la découverte du nouveau sel d’iodonium y est présentée avec une très brève séquence d’optimisation. La fin du chapitre rationalise la formation du produit tout en présentant ensuite l’intérêt de continuer le projet de maîtrise sur celui-ci. Le chapitre 2 porte sur la réactivité des sels de diaryliodonium appliquée au composé découvert au chapitre 1. Les réactions d’arylation et de couplage sont testées suivies d’une optimisation pour chacune. Des rendements modestes de 66% et de 65% ont été respectivement obtenus pour le produit d’arylation ainsi que le produit couplage. Le chapitre 3 porte principalement sur la réaction d’addition conjuguée d’aza-Michael. L’utilisation d’une amine seco

This review summarizes recent applications of copper or copper-based compounds as a nonprecious metal catalyst in N-nucleophiles-based dehalogenation (DH) reactions of halogenated aromatic compounds (Ar-Xs). Cu-catalyzed DH enables the production of corresponding nonhalogenated aromatic products (Ar-Nu), which are much more biodegradable and can be mineralized during aerobic wastewater treatment or which are principally further applicable. Based on available knowledge, the developed Cu-based DH methods enable the utilization of amines for effective cleavage of aryl-halogen bonds in organic solvents or even in an aqueous solution., Tento přehled shrnuje nedávné aplikace mědi nebo sloučenin na bázi mědi jako katalyzátoru neušlechtilých kovů při dehalogenačních (DH) reakcích halogenovaných aromatických sloučenin (Ar-Xs) na bázi N-nukleofilů. Cu katalyzovaný DH umožňuje výrobu odpovídajících nehalogenovaných aromatických produktů (Ar-Nu), které jsou mnohem lépe biologicky odbouratelné a mohou být mineralizovány při aerobním čištění odpadních vod nebo které jsou principiálně dále využitelné. Na základě dostupných poznatků vyvinuté DH metody na bázi Cu umožňují využití aminů pro efektivní štěpení aryl-halogenových vazeb v organických rozpouštědlech nebo i ve vodném roztoku.

Producción Científica, Metal-catalyzed C–H functionalizations on the aryl ring of anilines usually need cumbersome N-protection–deprotection strategies to ensure chemoselectivity. We describe here the Pd-catalyzed direct C–H arylation of unprotected anilines with no competition of the N-arylation product. The ligand [2,2′-bipyridin]-6(1H)-one drives the chemoselectivity by kinetic differentiation in the product-forming step, while playing a cooperating role in the C–H cleavage step. The latter is favored in an anionic intermediate where the NH moiety is deprotonated, driving the regioselectivity of the reaction toward ortho substitution., Ministerio de Ciencia, Innovación y Universidades (projects PID2019-111406GB-I00 and PID-2020-116861GB-I00), Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (projects VA224P20 and VA087-18)

The arylation of heteroatom nucleophiles is a central strategy to reach diarylated compounds that are key building blocks in agrochemicals, materials, and pharmaceuticals. Nucleophilic aromatic substitution is a classical tool for such arylations, and recent developments in hypervalent iodine-mediated arylations allow a wider scope of products. Herein, we combine the benefits of these strategies to enable an efficient and transition-metal-free difunctionalization of N-and O-nucleophiles with two structurally different aryl groups and to provide di-and triarylamines and diaryl ethers in one single step (>100 examples). The core of this strategy is the unique reactivity discovered with specifically designed fluorinated diaryliodonium salts, which unveils novel reaction pathways in hypervalent iodine chemistry. The methodology is suitable for diarylation of aliphatic amines, anilines, ammonia, and even water. It tolerates a wide variety of functional and protecting groups, with the retained iodine substituent easily accessible for derivatization of the products.

Producción Científica, Metal-catalyzed C–H functionalizations on the aryl ring of anilines usually need cumbersome N-protection–deprotection strategies to ensure chemoselectivity. We describe here the Pd-catalyzed direct C–H arylation of unprotected anilines with no competition of the N-arylation product. The ligand [2,2′-bipyridin]-6(1H)-one drives the chemoselectivity by kinetic differentiation in the product-forming step, while playing a cooperating role in the C–H cleavage step. The latter is favored in an anionic intermediate where the NH moiety is deprotonated, driving the regioselectivity of the reaction toward ortho substitution., Ministerio de Ciencia, Innovación y Universidades (projects PID2019-111406GB-I00 and PID-2020-116861GB-I00), Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (projects VA224P20 and VA087-18)

Producción Científica, Metal-catalyzed C–H functionalizations on the aryl ring of anilines usually need cumbersome N-protection–deprotection strategies to ensure chemoselectivity. We describe here the Pd-catalyzed direct C–H arylation of unprotected anilines with no competition of the N-arylation product. The ligand [2,2′-bipyridin]-6(1H)-one drives the chemoselectivity by kinetic differentiation in the product-forming step, while playing a cooperating role in the C–H cleavage step. The latter is favored in an anionic intermediate where the NH moiety is deprotonated, driving the regioselectivity of the reaction toward ortho substitution., Ministerio de Ciencia, Innovación y Universidades (projects PID2019-111406GB-I00 and PID-2020-116861GB-I00), Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (projects VA224P20 and VA087-18)

The merger of photoredox catalysis and organometallic chemistry has effectively enabled multiple cross-coupling pathways. Here we report a visible-light promoted photoredox-cobalt catalyzed Minisci reaction of N-heteroarenes under mild conditions, employing various boronic acids and derivatives as alkyl radical precursors. This study demonstrates the prominent ability of the Co co-catalyst to promote the oxidation step of the photocatalytic cycle following a reductive quenching pathway, thus avoiding the use of stoichiometric (inorganic) oxidants. This feature enables the straightforward application of photo-flow conditions, particularly attractive for an easy scale-up and to enhance the efficiency of the reaction (throughput: 0.78 mmol center dot h(-1) in flow vs. 0.02 mmol center dot h(-1) in batch). Furthermore, the process is predominantly selective towards the C2-alkylation of quinolines and a mechanistic rationale has been provided with both experimental and DFT calculation support. The developed protocol demonstrates broad applicability for the alkylation of different N-heteroarenes under suitable homogeneous conditions for a flow-compatible Minisci reaction.

We present a quantum chemistry (QM)-based method that computes the relative energies of intermediates in the Heck reaction that relate to the regioselective reaction outcome: branched (alpha), linear (beta), or a mix of the two. The calculations are done for two different reaction pathways (neutral and cationic) and are based on r2SCAN-3c single-point calculations on GFN2-xTB geometries that, in turn, derive from a GFNFF-xTB conformational search. The method is completely automated and is sufficiently efficient to allow for the calculation of thousands of reaction outcomes. The method can mostly reproduce systematic experimental studies where the ratios of regioisomers are carefully determined. For a larger dataset extracted from Reaxys, the results are somewhat worse with accuracies of 63% for beta-selectivity using the neutral pathway and 29% for alpha-selectivity using the cationic pathway. Our analysis of the dataset suggests that only the major or desired regioisomer is reported in the literature in many cases, which makes accurate comparisons difficult. The code is freely available on GitHub under the MIT open-source license: https:// github.com/jensengroup/HeckQM.

We present a quantum chemistry (QM)-based method that computes the relative energies of intermediates in the Heck reaction that relate to the regioselective reaction outcome: branched (alpha), linear (beta), or a mix of the two. The calculations are done for two different reaction pathways (neutral and cationic) and are based on r2SCAN-3c single-point calculations on GFN2-xTB geometries that, in turn, derive from a GFNFF-xTB conformational search. The method is completely automated and is sufficiently efficient to allow for the calculation of thousands of reaction outcomes. The method can mostly reproduce systematic experimental studies where the ratios of regioisomers are carefully determined. For a larger dataset extracted from Reaxys, the results are somewhat worse with accuracies of 63% for beta-selectivity using the neutral pathway and 29% for alpha-selectivity using the cationic pathway. Our analysis of the dataset suggests that only the major or desired regioisomer is reported in the literature in many cases, which makes accurate comparisons difficult. The code is freely available on GitHub under the MIT open-source license: https:// github.com/jensengroup/HeckQM.

The effect of copper and its compounds on halogenation and dehalogenation of aromatic compounds will be discussed in the proposed article. Cu oxidized to appropriate halides is an effective halogenation catalyst not only for the synthesis of halogenated benzenes or their derivatives as desired organic fine chemicals, but is also an effective catalyst for the undesirable formation of thermodynamically stable and very toxic polychlorinated and polybrominated aromatic compounds such as polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans accompanied incineration of waste contaminated with halogenated compounds or even inorganic halides. With appropriate change in reaction conditions, copper and its alloys or oxides are also able to effectively catalyze dehalogenation reactions, as will be presented in this review., Zatímco halogenidy měďnaté jsou katalyzátory halogenačních reakcí, měď je katalyticky aktivní i při dehalogenačních reakcích. Jednou z nejznámějších měďnatými solemi katalyzovaných reakcí je oxyhalogenace. Katalytické působení mědi se naopak uplatňuje při dehalogenaci PCDD/Fs obsažených např. v nespalitelných zbytcích.

Herein we disclose the synthesis of sterically encumbered dialkylnickel(II) complexes bearing 2,9-dimethyl-1,10phenanthroline ligands. A comparison with their unsubstituted analogues by both X-ray crystallography and theoretical calculations revealed significant distortions in their molecular structures. Eyring plots along with stoichiometric and photoexcitation studies revealed that sterically encumbered dialkylnickel(II) complexes enable facile C(sp3)-C(sp3) reductive elimination, thus offering an improved understanding of Ni catalysis.

We report a photocatalytic strategy for the chemodivergent radical benzylation of 4-cyanopyridines. The chemistry uses a single photoredox catalyst to generate benzyl radicals upon N-F bond activation of 2-alkyl N-fluorobenzamides. The judicious choice of different photocatalyst quenchers allowed us to select at will between mechanistically divergent processes. The two reaction manifolds, an ipso-substitution path proceeding via radical coupling and a Minisci-type addition, enabled selective access to regioisomeric C4 or C2 benzylated pyridines, respectively. Mechanistic investigations shed light on the origin of the chemoselectivity switch.

Herein, we report a photocatalytic procedure that enables the acylation/arylation of unfunctionalized alkyl derivatives in flow. The method exploits the ability of the decatungstate anion to act as a hydrogen atom abstractor and produce nucleophilic carbon-centered radicals that are intercepted by a nickel catalyst to ultimately forge C(sp3)−C(sp2) bonds. Owing to the intensified conditions in flow, the reaction time can be reduced from 12–48 hours to only 5–15 minutes. Finally, kinetic measurements highlight how the intensified conditions do not change the reaction mechanism but reliably speed up the overall process.

A transition metal-free approach for the N-arylation of amino acid derivatives has been developed. Key to this method is the use of unsymmetric diaryliodonium salts with anisyl ligands, which proved important to obtain high chemoselectivity and yields. The scope includes the transfer of both electron deficient, electron rich and sterically hindered aryl groups with a variety of different functional groups. Furthermore, a cyclic diaryliodonium salt was successfully employed in the arylation. The N-arylated products were obtained with retained enantiomeric excess.

Herein, we report a photocatalytic procedure that enables the acylation/arylation of unfunctionalized alkyl derivatives in flow. The method exploits the ability of the decatungstate anion to act as a hydrogen atom abstractor and produce nucleophilic carbon-centered radicals that are intercepted by a nickel catalyst to ultimately forge C(sp3)−C(sp2) bonds. Owing to the intensified conditions in flow, the reaction time can be reduced from 12–48 hours to only 5–15 minutes. Finally, kinetic measurements highlight how the intensified conditions do not change the reaction mechanism but reliably speed up the overall process.

Tout d’abord, ce document comprend une introduction sur les composés d’iode(III) et plus particulièrement, les sels de diaryliodonium. Par la suite, les différents radioisotopes et leurs productions sont présentés suivis des méthodes de marquages au fluor-18 incluant aussi une brève introduction à la TEP (Tomographie par émission de positrons). Les travaux de recherche de ce mémoire présentent la synthèse de composés permettant le marquage direct par échange isotopique fluor-19 (19F)/ fluor-18 18F pour le développement de traceurs peptidiques utilisés en imagerie TEP. La synthèse de ces composés se fait par une réaction d’arylation à l’aide de composé dérivé des sels de diaryliodonium soit par l’utilisation de zwitterion iodonium. La méthode de marquage utilisée est un échange isotopique à l’aide de groupements trifluoroborates pour l’introduction du radioisotope 18F. Le 18F est un émetteur de positrons qui permet d’effectuer l’imagerie TEP. Dans le chapitre 1, trois différentes approches de synthèse des groupements prosthétiques porteurs de groupements trifluoroborates seront abordées. Ces approches présentent la synthèse des composés d’arylation à l’aide de zwitterion iodonium et des tests de radiomarquage par échange isotopique 19F/18F. La première approche présentée consiste en l’arylation de divers nucléophiles présents sur des acides aminés naturels à partir de zwitterions iodonium pour la préparation d’aryles o-trifluoroborate dérivés d’acides aminés comme précurseurs pour les échanges isotopiques 18F/19F. Cette approche a pour perspective d’introduire l’aryltrifluoroborate sur un acide aminé qui pourrait être utilisé en couplage peptidique par la suite ou directement sur un peptide. Les études de radiomarquage n’ont malheureusement pas été possibles, puisque les aryltrifluoroborates générés présentent une trop faible stabilité en conditions aqueuses. La deuxième approche consiste à effectuer l’arylation de différents groupements qui serviront d’espaceurs ent

A dual platform for forging sp(2)-sp(3) and sp(3)-sp(3) carbon bonds via catalytic beta-scission of aliphatic alcohol derivatives with both aryl and alkyl halides is disclosed. This protocol is distinguished by its wide substrate scope and broad applicability, even in the context of late-stage functionalization.

The β-arylation and -alkenylation of trifluoromethylacrylic acid with arylboronic acids and alkenes proceed smoothly under rhodium(III) catalysis. The procedures provide useful synthetic routes from readily available building brocks to β-aryl-α-trifluoromethylpropanoic acid and 5,5,5-trifluoro-1,3-butadiene derivatives. Some of the obtained butadienes exhibit strong fluorescence in the solid state.

An a-vinylation of enolizable ketones has been developed by using b-bromostyrenes and a KOtBu/NMP system. β,γ-Unsaturated ketones of E configuration were obtained in excellent yield and selectivity. Further synthetic possibilities are highlighted by one-pot functionalization via trapping of intermediate dienolates with alkyl, allyl, benzyl, and propargyl halidesto generate quaternary centers. The reported transformation is believed to proceed via phenylacetylene and propargylic alcohol intermediates.

The site-selective functionalization of C-H bonds within a peptide framework remains a challenging task of prime synthetic importance. Herein, the first Pd-catalyzed delta-C(sp(2))-H acylation of Phe containing peptides with aldehydes is described. This oxidative coupling is distinguished by its site-specificity, tolerance of sensitive functional groups, scalability, and enantiospecificity and exhibits entire chemoselectivity for Phe motifs over other amino acid units. The compatibility of this dehydrogenative acylation platform with a number of oligopeptides of high structural complexity illustrates its ample opportunities for the late-stage peptide modification and bioconjugation.

The site-selective functionalization of C-H bonds within a peptide framework remains a challenging task of prime synthetic importance. Herein, the first Pd-catalyzed delta-C(sp(2))-H acylation of Phe containing peptides with aldehydes is described. This oxidative coupling is distinguished by its site-specificity, tolerance of sensitive functional groups, scalability, and enantiospecificity and exhibits entire chemoselectivity for Phe motifs over other amino acid units. The compatibility of this dehydrogenative acylation platform with a number of oligopeptides of high structural complexity illustrates its ample opportunities for the late-stage peptide modification and bioconjugation.

This thesis describes investigations into the total synthesis of the sterically hindered biaryl natural products, the 5,3’- and 7,3’-linked naphthylisoquinoline alkaloids.Chapter 1 outlines the synthetic strategies that have been developed by other groups for accessing the unique structure of the naphthylisoquinoline alkaloids. Previous work in the Morris group on the development of a convergent ortho-arylation strategy is described and the motivation for this work explained.Chapter 2 describes the completion of the total synthesis of all known 5,3’-linked naphthylisoquinoline alkaloids. In this work, a model system was used to identify conditions for the oxidation of the 1,2,3,4-tetrahydroisoquinoline moiety (2.15) of the natural products to the corresponding 3,4-dihydroisoquinoline 1.135. The core the natural products was accessed in 8 steps via Pinhey-Barton ortho-arylation of naphthol 1.113 using isoquinoline-substituted lead(IV) triacetate 2.21. Protection of the naphthol as the MOM-ether was followed by oxidation to complete the total syntheses of ancistrotanzanine A (1.122) and ancistrotectorine D (1.123) in 12 steps, while ancistrotectorine C (1.124) was accessed in 10 steps via a reductive amination protocol. Biological testing of the three natural products as well as atrop-ancistrotectorine C (2.29) identified moderate anti-malarial activity and low cytotoxicity.Chapter 3 details the investigation into organobismuth(V) compounds as an alternative to the aryllead(IV) triacetates used previously in the group for sterically hindered biaryl couplings. This resulted in the preparation and ligand-selective coupling of unsymmetrically substituted bismuthonium 3.23 to naphthol 1.113 to assemble the core of the 5,3’-linked naphthylisoquinoline alkaloids. In Chapter 4 this methodology is extended to the 7,3’-linked natural products. This was enabled by the development of a 6-step, asymmetric synthesis of 7-bromotetrahydroisoquinoline 4.34, which was converted to the

The site-selective functionalization of C-H bonds within a peptide framework remains a challenging task of prime synthetic importance. Herein, the first Pd-catalyzed delta-C(sp(2))-H acylation of Phe containing peptides with aldehydes is described. This oxidative coupling is distinguished by its site-specificity, tolerance of sensitive functional groups, scalability, and enantiospecificity and exhibits entire chemoselectivity for Phe motifs over other amino acid units. The compatibility of this dehydrogenative acylation platform with a number of oligopeptides of high structural complexity illustrates its ample opportunities for the late-stage peptide modification and bioconjugation.

The site-selective functionalization of C-H bonds within a peptide framework remains a challenging task of prime synthetic importance. Herein, the first Pd-catalyzed delta-C(sp(2))-H acylation of Phe containing peptides with aldehydes is described. This oxidative coupling is distinguished by its site-specificity, tolerance of sensitive functional groups, scalability, and enantiospecificity and exhibits entire chemoselectivity for Phe motifs over other amino acid units. The compatibility of this dehydrogenative acylation platform with a number of oligopeptides of high structural complexity illustrates its ample opportunities for the late-stage peptide modification and bioconjugation.

The site-selective functionalization of C-H bonds within a peptide framework remains a challenging task of prime synthetic importance. Herein, the first Pd-catalyzed delta-C(sp(2))-H acylation of Phe containing peptides with aldehydes is described. This oxidative coupling is distinguished by its site-specificity, tolerance of sensitive functional groups, scalability, and enantiospecificity and exhibits entire chemoselectivity for Phe motifs over other amino acid units. The compatibility of this dehydrogenative acylation platform with a number of oligopeptides of high structural complexity illustrates its ample opportunities for the late-stage peptide modification and bioconjugation.

The site-selective functionalization of C-H bonds within a peptide framework remains a challenging task of prime synthetic importance. Herein, the first Pd-catalyzed delta-C(sp(2))-H acylation of Phe containing peptides with aldehydes is described. This oxidative coupling is distinguished by its site-specificity, tolerance of sensitive functional groups, scalability, and enantiospecificity and exhibits entire chemoselectivity for Phe motifs over other amino acid units. The compatibility of this dehydrogenative acylation platform with a number of oligopeptides of high structural complexity illustrates its ample opportunities for the late-stage peptide modification and bioconjugation.

A straightforward approach to the synthesis of the challenging 12-arylindolo[1,2- c ]quinazolin-6(5 H)-ones through the palladium-catalyzed direct arylation of N -benzyl and NH-free [1,2- c ]quinazolin-6(5 H)-ones with aryl halides is described.

Práce je zaměřena na studium reaktivity diazoniových solí pro C-H arylace tryprofanů. Pro substituované benzendiazoniové soli byly určeny relativní hodnoty jejich disociačních energií vazeb (BDE) a ty korelovány s vypočtenými i experimentálně zjištěnými parametry, jako například vlivem substituce na polohu vibračních pásů, či Hammettovskými konstantami., This work is focused on determination of selected properties of substituted benzenediazonium salts such as relative bond dissociation energy (BDE) or vibration maxima of N three N bonds and correlations of the experimentally obtained values with calculated ones., Fakulta chemicko-technologická, Studentka prezentovala svoji bakalářskou práci a vyjádřila se k připomínkám., Dokončená práce s úspěšnou obhajobou

A transition metal-free formal synthesis of phenoxazine is presented. The key step of the sequence is a high-yielding O-arylation of a phenol with an unsymmetrical diaryliodonium salt to provide an ortho-disubstituted diaryl ether. This species was cyclized to acetylphenoxazine in moderate yield. The overall yield in the three-step sequence is 72% based on recovered diaryl ether. An interesting, unusually stable iodine(III) intermediate in the O-arylation was observed by NMR and could be converted to the product upon longer reaction time.

A transition metal-free formal synthesis of phenoxazine is presented. The key step of the sequence is a high-yielding O-arylation of a phenol with an unsymmetrical diaryliodonium salt to provide an ortho-disubstituted diaryl ether. This species was cyclized to acetylphenoxazine in moderate yield. The overall yield in the three-step sequence is 72% based on recovered diaryl ether. An interesting, unusually stable iodine(III) intermediate in the O-arylation was observed by NMR and could be converted to the product upon longer reaction time.

A transition metal-free formal synthesis of phenoxazine is presented. The key step of the sequence is a high-yielding O-arylation of a phenol with an unsymmetrical diaryliodonium salt to provide an ortho-disubstituted diaryl ether. This species was cyclized to acetylphenoxazine in moderate yield. The overall yield in the three-step sequence is 72% based on recovered diaryl ether. An interesting, unusually stable iodine(III) intermediate in the O-arylation was observed by NMR and could be converted to the product upon longer reaction time.

Density functional theory calculations are used to study the reaction mechanism and origins of C2-selectivity in a rhodium-catalyzed arylation of indole. It is shown that the reaction is catalyzed by an anionic Rh(III)-intermediate that activates the substrate through a concerted-metalation deprotonation. Dissociation of pivalic acid and subsequent reductive elimination generate the arylated indole product. Oxidative addition of the aryl iodide and a subsequent ligand exchange regenerates the active catalytic species. The origin of the regioselectivity is found to be the more favorable interaction between the 2-indolyl fragment and the metal center compared to the 3-indolyl fragment. Moreover, the better interaction of the pivalate ligands with the substrate in the transition state for the activation of C2H compared to the transition state for the C3H activation further favors the C2-selectivity.

A transition metal-free formal synthesis of phenoxazine is presented. The key step of the sequence is a high-yielding O-arylation of a phenol with an unsymmetrical diaryliodonium salt to provide an ortho-disubstituted diaryl ether. This species was cyclized to acetylphenoxazine in moderate yield. The overall yield in the three-step sequence is 72% based on recovered diaryl ether. An interesting, unusually stable iodine(III) intermediate in the O-arylation was observed by NMR and could be converted to the product upon longer reaction time.

A transition metal-free formal synthesis of phenoxazine is presented. The key step of the sequence is a high-yielding O-arylation of a phenol with an unsymmetrical diaryliodonium salt to provide an ortho-disubstituted diaryl ether. This species was cyclized to acetylphenoxazine in moderate yield. The overall yield in the three-step sequence is 72% based on recovered diaryl ether. An interesting, unusually stable iodine(III) intermediate in the O-arylation was observed by NMR and could be converted to the product upon longer reaction time.