Silver-catalyzed 2-isocyanobiaryls insertion/cyclization with phosphine oxides: synthesis of 6-phosphorylated phenanthridines

Thermal and Photoinduced Radical Cascade Annulation using Aryl Isonitriles: An Approach to Quinoline-Derived Benzophosphole Oxides

Herein, we present a radical cascade addition cyclization sequence to access quinoline-based benzophosphole oxides from ortho-alkynylated aromatic phosphine oxides using various aryl isonitriles as radical acceptors and inexpensive tert-butyl-hydroperoxide (TBHP) as a terminal oxidant in the presence of a catalytic amount of silver acetate. Alternatively, the same cascade can be realized through a sustainable photochemical approach utilizing 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) as an organic photocatalyst at room temperature. The introduced modular approach shows broad functional group tolerance and offers straightforward access to complex P,N-containing polyheterocyclic arenes. These novel π-extended benzophosphole oxides exhibit interesting photophysical and electrochemical properties such as absorption in the visible region, emission and reversible reduction at low potentials, which makes them promising for potential materials science applications. The photophysical properties can further be tuned by the addition of external Lewis and Brønsted acids.

Visible-Light-Mediated Annulation/Thiolation of 2-Isocyanobiaryls with Disulfides to Organoylthiophenanthridines Derivatives

A visible-light-induced annulation/thiolation of 2-isocyanobiaryls with dialkyl(aryl)disulfides has been established, delivering a sustainable and atom-economic route to 6-organoylthiophenanthridines with wild functional group tolerance and good to excellent yields under oxidant-, base-, and transition-metal-free conditions.

Photocatalytic Umpolung Strategy for the Synthesis of α-Amino Phosphine Oxides and Deuterated Derivatives

Direct, economical, and green synthesis of deuterated α-amino phosphine oxides remains an elusive challenge in synthetic chemistry. Herein, we report a visible-light-driven umpolung strategy for synthesizing deuterated α-amino phosphine oxides from isocyanide using 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene as the photocatalyst and D2O as the deuterium source. Moreover, the streamlined and sustainable methodology can be applied in the modification of amino acids, natural products, and drugs. The strong antiproliferative activity of the desired products indicates that the method could provide a novel privileged scaffold for antitumor drug development.

Copper(II)-catalyzed cascade Csp2-P/C-C bond formation to construct benzo[d]thiazol-2-ylphosphonates

A novel, copper(II)-catalyzed cascade Csp2-P/C-C bond formation in o-haloaryl isothiocyanates with organophosphorus esters has been developed under mild conditions. A series of benzo[d]thiazol-2-ylphosphonates were synthesized in moderate to good yields. Different from the traditional method of obtaining these scaffolds with radical reactions, the method proposed allows accessing them via ionic reactions and has the advantages of easy access to raw materials and simple operation. Finally, we carried out a gram-scale experiment to further demonstrate the scalability of this strategy in the efficient synthesis of benzo[d]thiazol-2-ylphosphonates.

Mn-catalyzed electrooxidative radical phosphorylation of 2-isocyanobiaryls

As an efficient and green synthesis method, the electrocatalysis hydrogen evolution coupling reaction has been widely used by chemists to realize the combining of two nucleophiles. In this work, an alternative method to synthesize 6-phosphorylated phenanthridines has been developed by synergistically utilizing electrocatalysis and Mn catalysis, with moderate to relatively good yields achieved. Mild and oxidant-free conditions make this synthetic method applicable in various settings.

I2-mediated Csp2–P bond formation via tandem cyclization of o-alkynylphenyl isothiocyanates with organophosphorus esters

A highly efficient molecular-iodine-catalyzed cascade cyclization reaction has been developed, creating a series of 4H-benzo[d][1,3]thiazin-2-yl phosphonates in moderate to excellent yields. This approach benefits from metal-free catalysts and available raw materials.

Unexpected ester and phosphonate radical generation by hypervalent iodine compounds for synthesizing 6-phenanthridine derivatives

An unprecedented elimination of diazomethane process of a diazo group-bearing hypervalent iodine reagent has been described.

Direct 1,1-Bisphosphonation of Isocyanides: Atom- and Step-Economical Access to Bisphosphinoylaminomethanes

An atom- and step-economical strategy for the synthesis of bisphosphinoylaminomethanes is reported. This metal-free bisphosphinylation reaction proceeded smoothly through a base-mediated direct 1,1-bisphosphonation of phosphine oxides and isocyanides under mild conditions. The present method offers a facile, efficient, and general approach to a broad range of bisphosphinoylaminomethane derivatives in moderate to good yields.

Mn(III)-Mediated Cascade Cyclization of 3-Isocyano-[1,1'-biphenyl]-2-carbonitrile with Arylboronic Acid: Construction of Pyrrolopyridine Derivatives

A Mn(III) mediated cascade cyclization of new designed multifunctionalized 3-isocyano-[1,1'-biphenyl]-2-carbonitrile with arylboronic acid to construct pyrrolopyridine derivatives is developed. A series of pyrroloporidine compounds have been constructed through the formation of two new C-C bonds and one C-N bond via a radical pathway.

Convenient synthesis of 6-alkyl phenanthridines and 1-alkyl isoquinolines via silver-catalyzed oxidative radical decarboxylation

A convenient and efficient protocol for the synthesis of 6-alkyl phenanthridines and 1-alkyl isoquinolines has been developed. The reaction relies on the coupling of 2-isocyanobiphenyls and vinyl isonitriles with alkyl radicals formed by the silver-catalyzed decarboxylation of stoichiometric aliphatic carboxylic acids, and affords diverse phenanthridine and isoquinoline derivatives under mild reaction conditions. The experiment of β-scission of cyclobutylcarbinyl radicals is used to shed light on the reaction mechanism.

Metal-catalyzed C–H functionalization involving isocyanides

This review demonstrates the metal-catalyzed incorporation of isocyanides into C–H functionalization to establish complicated reactions utilizing synergistic effects.

Ag-catalyzed C-H/C-C bond functionalization

Silver, known and utilized since ancient times, is a coinage metal, which has been widely used for various organic transformations in the past few decades. Currently, the silver-catalyzed reaction is one of the frontier areas in organic chemistry, and the progress of research in this field is very rapid. Compared with other transition metals, silver has long been believed to have low catalytic efficiency, and most commonly, it is used as either a cocatalyst or a Lewis acid. Interestingly, the discovery of Ag-catalysis has been significantly improved in recent years. Especially, Ag(i) has been demonstrated as an important and versatile catalyst for a variety of organic transformations. However, so far, there has been no systematic review on Ag-catalyzed C-H/C-C bond functionalization. In this review, we will focus on the development of Ag-catalyzed C-H/C-C bond functionalization and the corresponding mechanism.

Co(acac)2/O2-catalyzed oxidative isocyanide insertion with 2-vinylanilines: efficient synthesis of 2-aminoquinolines

A series of 2-aminoquinolines were afforded by Co(acac)₂ catalyzed isocyanide insertion with 2-vinylanilines under an O₂ atmosphere.

Recent progress in imidoyl radical-involved reactions

This review discusses the recent progress in imidoyl radical-involved reactions including the synthesis of functionalized heterocycles, nitriles, imines, amines,etc.

Preparation of phenanthrenes from ortho-amino-biphenyls and alkynes via base-promoted homolytic aromatic substitution

Phenanthrenes are prepared from ortho-aminobiphenyls and acetylenes via base-promoted homolytic aromatic substitution.