Ruthenium-Catalyzed Regioselective Alkenylation/Tandem Hydroamidative Cyclization of Unmasked Quinazolinones Using Terminal Alkynes

Ruthenium-catalyzed amide directed C_sp2–H activation of the quinazolinone scaffold has been demonstrated, leading to the selective mono- or dialkenylation in moderate to good yields to achieve medicinally important stilbene containing quinazolinones. The terminal alkyne is utilized as a coupling partner, which resulted in the selective <i>trans</i>-alkene formation. Electron-deficient phenylacetylenes facilitate alkenylation followed by tandem hydroamidation of the newly generated <i>trans</i>-double bond to provide novel quinazolinone alkaloids related to the Luotonine class of natural products

P‑Arylation: Arynes to Aryl-Phosphonates, -Phosphinates, and -Phosphine Oxides

Synthesis of organo-phosphorus compounds and their application in organic synthesis and life sciences has been a topic of contemporary interest. Michaelis–Arbuzov reaction is the most extensively utilized method for their preparation, which works well only with aliphatic halides. Hence, relatively harsh reaction conditions using transition-metal-catalyzed P-arylation (Arbuzov/Hirao reaction) are used for the preparation of aryl-phosphorus compounds. Presented herein is a competent process for the synthesis of aryl-phosphonates, -phosphinates, and -phosphine oxides by making an efficient use of arynes for C–P bond construction

Synthesis of Succinimide Derivatives by NHC-Catalyzed Stetter Reaction of Aromatic Aldehydes with <i>N</i>‑Substituted Itaconimides

An N-heterocyclic carbene-catalyzed intermolecular Stetter reaction of aromatic aldehydes with <i>N</i>-substituted itaconimides has been developed. A delicate balance between the Stetter reaction and the competing isomerization of the itaconimide double bond has been achieved in this operationally simple reaction to afford valuable new succinimide derivatives containing 1,4 and 1,5 dicarbonyl scaffolds in good to excellent yields. The reaction tolerates variable substituents on both aldehydes and <i>N</i>-substituted itaconimides

Transition-Metal-Free C–S Bond Formation: A Facile Access to Aryl Sulfones from Sodium Sulfinates via Arynes

Sulfones have been attractive targets for synthetic organic chemists owing to their immense applications in medicinal, material, and synthetic chemistry. In this context, an efficient transition-metal-free process has been demonstrated, wherein a broad range of alkyl/aryl/heteroaryl sodium sulfinates react with varyingly substituted aryne precursors (<i>o</i>-silyl aryl triflates) under mild reaction conditions to afford structurally diverse sulfones in good to excellent yields

Silver-Mediated Oxidative Decarboxylative Intramolecular Asymmetric Radical Cyclization (C_sp3–C_sp2) via Memory of Chirality: Access to Circumdatin Alkaloids

A novel silver-mediated oxidative decarboxylative intramolecular asymmetric radical cyclization has been developed to form a C_sp3–C_sp2 bond via memory of chirality. The application of the process has been demonstrated for the synthesis of the circumdatin class of alkaloids in high enantiopurity with retention of the configuration. The developed protocol is mild and works with an inexpensive silver catalyst in the absence of ligand, base, or additives. The involvement of a monoradical in the reaction has been established by trapping the radical intermediate

Nucleophilic Nitration of Arynes by Sodium Nitrite and its Multicomponent Reaction Leading to Double-Functionalized Arenes

An unusual nucleophilic nitration of arynes by NaNO₂ in the presence of water has been developed, and the concept was further demonstrated to accomplish a double functionalization of arynes using a multicomponent reaction protocol to synthesize pharmaceutically important (2-nitrophenyl)­methanol derivatives. Such substitution ortho to −NO₂ is difficult by other means. The reaction conditions are mild and avoid the use of strong acids, expensive transition metal catalysts, and additives

Application of Sulfur Ylides in 1,2-Difunctionalization of Arynes via Insertion into a C–S σ‑Bond

A novel reactivity of sulfur ylides has been demonstrated in a transition-metal-free protocol to access <i>ortho</i>-substituted thioanisole derivatives by insertion of arynes into a C–S σ-bond in moderate to good yields. The reaction involves the formation of C–C and C–S bonds and consecutive breaking of two C–S bonds under operationally mild reaction conditions

Pd-Catalyzed Regioselective Mono-Arylation: Quinazolinone as the Inherent Directing Group for C(sp²)–H Activation

The Pd-catalyzed quinazolinone-directed regioselective monoarylation of aromatic rings by C–H bond activation is developed. A broad substrate scope is demonstrated for both quinazolinone as well as diaryliodonium triflates. The use of a base was found to be crucial for this transformation, unlike for the known nitrogen-directed arylations. All of the novel quinazolinones of biological interest were synthesized by using the operationally simple Pd­(II)-catalyzed arylation reaction