Organic Letters

This work describes a visible-light-induced Ullmann C-O coupling between aryl halides and phenols at room temperature without an external photocatalyst. Preliminary mechanistic studies suggest that the in situ-formed LCu(I)-phenoxide complex functions as both a photosensitizer and an active catalyst. The synthetic utility of this photoinduced Ullmann-type coupling was demonstrated by a gram-scale…

A relay Pd(0)/Brønsted base-catalyzed cascade reaction between <i>N</i>-trifluoroethyl isatin ketimines and propargylic carbonates is reported, proceeding through Pd(0)-catalyzed allenylation followed by Brønsted base-directed deprotonation, 5-<i>endo</i>-<i>trig</i> cyclization, ring expansion, and aromatization. A broad range of pyrrolopyrimidinone frameworks are furnished in high yields with g…

A robust strategy for the hydrothiolation of heterocycloalkynes with in situ generated dithiocarbamic acids, "Strain-Promoted diThiocarbamic acid-Alkyne Click" (SPTAC), was developed and successfully extended to diverse cycloalkynes and a wide range of amines and their hydrochlorides, affording hydrothiolation adducts in high to excellent yields. DFT calculations revealed a concerted pseudopericy…

A straightforward three-step synthesis of a thiophene-rich 3-fold symmetric core structure, benzo[1,2-<i>b</i>:3,4-<i>b</i>':5,6-<i>b</i>″]trithieno[3,2-<i>b</i>:6,5-<i>b</i>':9,8-<i>b</i>″]trithiophene (BTTT), was developed. The α-positions of the outermost thiophene rings can be readily modified via iridium-catalyzed borylation followed by the Suzuki-Miyaura cross-coupling reaction or the direc…

Radical-mediated rearrangement reactions serve as a powerful strategy for the construction of novel molecular frameworks. Herein, we report a photochemical four-component 1,4-aryl migration protocol for the highly regioselective synthesis of functionalized β-(hetero)arylethylamines. This practical approach employs readily accessible <i>N</i>-allylbenzamides and aryl thianthrenium salts, along wit…

A versatile synthesis of chiral spirocyclic sultams with a tunable ring size via nickel-catalyzed asymmetric <i>anti</i>-arylative cyclization of alkyne-tethered <i>N</i>-sulfonyl ketimines with arylboronic acids has been reported. This protocol exhibits exceptional efficiency, providing a broad array of chiral [5,6]-spirocyclic and [5,5]-spirocyclic sultams with excellent yields and enantioselec…

A copper-catalyzed carboboration of acetylene with Knoevenagel-type Michael acceptors has been achieved by using a bidentate phosphine ligand, affording <i>Z</i>-alkenyl boronates in good to excellent yields. This new catalytic system overcomes the limitations of our earlier NHC-Cu catalytic system. The addition of EtO-9-BBN as a buffering additive effectively suppresses undesired decomposition p…

The first dirhodium(II)-catalyzed synthesis of propellanes is established via a formal dicarbene-mediated cyclopropanation/C-H insertion cascade using readily available 1,6-enynes as carbene precursors. A key finding is that the competitive pathway between C-H insertion and carbene dimerization can be effectively controlled through solvent regulation. This one-pot transformation afforded a challe…

This study presents a regioselective ring-opening method for 2-substituted benzimidazoles, utilizing in situ-generated difluorocarbene as a key electrophile. Employing sodium chlorodifluoroacetate as the carbene precursor and Na₂CO₃ as the base, the reaction directly affords valuable 2-carbonyl phenyl isocyanides. Mechanistic studies, including HRMS (using ¹⁸O-lab…

Axially chiral diaryl ethers are important structural motifs, but their catalytic atroposelective construction remains challenging due to the low racemization barrier of the C-O axis. This work introduces an N-heterocyclic carbene (NHC)-catalyzed desymmetrizative amidation strategy for the direct enantioselective synthesis of C-O axially chiral benzoimides. The reaction employs readily available …

This work describes an efficient Pd-catalyzed three-component annulation process of aryl iodides and ynamides. A wide variety of 9-aminophenanthrenes bearing various functional groups can be obtained in up to 94% yield. The reaction likely proceeds via a 3-amino-substituted pallada(IV)cycle through sequential reaction processes. It appears that the formation of the aryl-vinyl bond is preferred ov…

A palladium-catalyzed annulation strategy for the synthesis of polycyclic heteroaromatic compounds incorporating a coumarin scaffold is developed. A key feature of this transformation is the use of a bidentate directing group composed of an amino and amide moiety, which enables precise control over periselective C-H activation and subsequent annulation. This robust protocol tolerates diverse coup…