Cu(OAc)₂‑Mediated Cascade Annulation of Diarylalkyne Sulfonamides through Dual C–N Bond Formation: Synthesis of 5,10-Dihydro­indolo­[3,2‑<i>b</i>]indoles

An unusual cascade reaction featuring annulation of diarylalkyne sulfonamides to form 5,10-dihydro­indolo­[3,2-<i>b</i>]­indoles has been realized with Cu­(OAc)₂ as the sole oxidant. This unprecedented process encompasses two sequential C–N bond formations, allowing for an efficient synthesis of the biologically important indoloindole derivatives

Intramolecular Functionalization of Benzylic Methylene Adjacent to the Ring Nitrogen Atom in <i>N</i>‑Aryltetrahydroisoquinoline Derivatives

Functionalization at the benzylic methylene group that is adjacent to the ring nitrogen atom in a series of <i>N</i>-aryltetrahydroisoquinoline compounds has been realized through intramolecular cross-dehydrogenative coupling reactions. The presented transformation provided straightforward access to the formation of C­(sp³)–Y (Y = C, N or O) bond via I­(III) reagent

Synthesis of Chromeno[2,3‑<i>b</i>]indol-11(6<i>H</i>)‑one via PhI(OAc)₂‑Mediated Intramolecular Oxidative C(sp²)–N(H₂) Bond Formation

Various chromeno­[2,3-<i>b</i>]­indol-11­(6<i>H</i>)-ones were conveniently constructed via phenyliodine­(III) diacetate (PIDA)-mediated intramolecular oxidative annulation. This method, while realizing a direct oxidative C–N bond formation between an aromatic ring and a pendent free-NH₂ moiety, features a metal-free protocol, mild reaction conditions, simple workup, and the ready availability of the starting substrates

PhICl₂ and Wet DMF: An Efficient System for Regioselective Chloroformyloxylation/α-Chlorination of Alkenes/α,β-Unsaturated Compounds

PhICl₂ in wet DMF was found to form an efficient system for realizing difunctionalization of various alkenes and olefinic derivatives possessing a wide range of functional groups. This novel methodology provides convenient access to either regioselective chloroformyloxylated products or α-chlorinated olefinic products, depending on the type of structure of the original unsaturated starting material. The mechanism of the reaction is proposed and discussed

Synthesis of Diversely Substituted Indoloquinolinones via Pd(II)/Cu(II)-Mediated Oxidative C–C Bond Formation and I(III)-Mediated C–N Bond Formation

A series of indoloquinolinones bearing different aromatic substitutents were readily synthesized starting from an aryl amine, a methyl 3-oxo-3-phenylpropanoate derivative, and methoxylamine through a series of reactions of coupling/enamination, oxidative annulation, a one-pot sequence of N-alkylation, saponification and methoxyamidation, and final intramolecular oxidative C–N bond formation. The underpinning of the strategy entails Pd­(OAc)₂/Cu­(OAc)₂-mediated oxidative C­(sp²)–C­(sp²) bond formation and I­(III)-mediated oxidative C­(sp²)–N bond formation

Hypervalent Iodine-Mediated Oxygenation of <i>N</i>,<i>N</i>‑Diaryl Tertiary Amines: Intramolecular Functionalization of sp³ C–H Bonds Adjacent to Nitrogen

An intramolecular C­(sp³)–O bond formation has been achieved via PhI­(OAc)₂/NaN₃-mediated oxygenation of <i>N</i>,<i>N</i>-diaryl tertiary amines. The appealing features of this method include mild reaction conditions, absence of heavy-metal catalysts, and the direct intramolecular functionalization of sp³ C–H bonds adjacent to nitrogen

Hypervalent Iodine-Mediated Intramolecular <i>trans</i>-Amino­car­box­ylation and Oxoamino­carbox­ylation of Alkynes: Divergent Cascade Annulations of Isocoumarins under Metal-Free Conditions

An exclusive <i>trans</i>-aminocarboxylation and oxoaminocarboxylation of diarylalkynes were realized through hypervalent iodine-mediated cascade annulations under metal-free conditions, leading to divergent assembly of fused or spiro polycyclic heterocycles with a dosage of the hypervalent iodine oxidant. The mechanisms for the formation of both products are proposed

Chiral Aryliodine-Mediated Enantioselective Organocatalytic Spirocyclization: Synthesis of Spirofurooxindoles via Cascade Oxidative C–O and C–C Bond Formation

An enantioselective organocatalytic oxidative spirocyclization of alkyl 3-oxopentanedioate monoamide derivatives leading to the formation of diverse spirofurooxindoles with high enantioselectivity has been realized via chiral aryliodine-mediated cascade C–O and C–C bond formations. The reaction is postulated to proceed via oxidative C–O bond formation followed by oxidative C–C bond formation, with the latter being the enantioselectivity-determining step

Direct Conversion of <i>N</i>‑Alkoxyamides to Carboxylic Esters through Tandem NBS-Mediated Oxidative Homocoupling and Thermal Denitrogenation

Treatment of <i>N</i>-alkoxyamides with NBS in toluene was found to conveniently afford the corresponding carboxylic esters, including those bearing a bulky or long-chain substituent, in satisfactory to excellent yields. This approach not only represents a convenient and economic approach to a direct transformation of an alkoxyamide moiety into the carboxylic ester functional group, via oxidative homocoupling and the subsequent thermal denitrogenation, but also facilitates the synthesis of sterically hindered carboxylic esters

Chiral Aryliodine-Mediated Enantioselective Organocatalytic Spirocyclization: Synthesis of Spirofurooxindoles via Cascade Oxidative C–O and C–C Bond Formation

An enantioselective organocatalytic oxidative spirocyclization of alkyl 3-oxopentanedioate monoamide derivatives leading to the formation of diverse spirofurooxindoles with high enantioselectivity has been realized via chiral aryliodine-mediated cascade C–O and C–C bond formations. The reaction is postulated to proceed via oxidative C–O bond formation followed by oxidative C–C bond formation, with the latter being the enantioselectivity-determining step