Copper-Catalyzed Direct Syntheses of Phenoxypyrimidines from Chloropyrimidines and Arylboronic Acids: A Cascade Avenue and Unconventional Substrate Pairs.

This letter describes the first synthetic methodology for phenoxypyrimidines that avoids the direct use of phenols or their salts. In contrast to the general trend of delivering Suzuki-Miyaura cross-coupling products in reactions between aryl or alky halides and arylboronic acids, the substrate pairs used herein (chloropyrimidines and arylboronic acids) led to C-O bond formation under the reaction conditions. In total, 25 phenoxypyrimidines were successfully synthesized using the described protocol, 6 of which had a structural resemblance to etravirine.

Pd(II)-Catalyzed oxidative alkenylation of 4-hydroxycoumarin with maleimide via a C-H bond activation strategy.

A Pd(ii)-catalyzed oxidative alkenylation of 4-hydroxycoumarins with maleimides for the synthesis of 4-hydroxy-3-maleimidecoumarins has been described. This methodology proceeds via C-H activation and C(sp2)-C(sp2) bond formation providing a series of alkenylated Heck-type products.

A palladium-catalyzed cascade process for spirooxindole: an alternative way for the synthesis of spiro(indoline-3,2'-quinazolin)-2-ones.

A palladium-catalyzed cascade strategy has been developed for one-pot synthesis of functionalized spiro(indoline-3,2'-quinazolin)-2-one derivatives from readily available starting materials. The reaction proceeds via C-C and two C-N bond formations in a single reaction operation. This method offers an attractive pathway for the synthesis of a broad range of spiro(indoline-3,2'-quinazolin)-2-ones in good yields.

o-Quinone Methides and o-Quinone Sulfides via Arynes: Synthesis of Ortho-Disubstituted Arenes and Heterocycles.

In recent decades, o-quinone methides and o-quinone sulfides have been extensively highlighted as reactive intermediates for the synthesis of diversely functionalized ortho-disubstituted arenes and heterocycles. Additionally, ortho-disubstituted arenes offer a constructive path for the synthesis of fused carbocycles, heterocycles, natural products, and drug candidates. In the lieu of that, this Synopsis highlights a comprehensive overview on the potential applications of in situ generated o-quinone methides and o-quinone sulfides for one-pot synthesis of ortho-disubstituted arenes and heterocycles via arynes.

Exploration of Kobayashi's aryne precursor: a potent reactive platform for the synthesis of polycyclic aromatic hydrocarbons.

Arynes due to their transient nature leads to remarkable and versatile applications in the synthetic world. Apparently, researchers have focused on the construction of simple to complex π-conjugated systems using arynes as the reactive platform. In this regard, Kobayashi's aryne precursor has shown a great extent of reactivity and afforded significant advancement in the synthesis of polycyclic aromatic systems with wide practical utility. This review emphasizes the extensive utilization of Kobayashi's aryne intermediates and their derivatives for the synthesis of different classes of polycyclic aromatic hydrocarbons (PAHs).

Indane-Fused Spiropentadiene Chromanones: A Pd-Catalyzed Spiroannulation Followed by Cyclization via C-H Activation Strategy.

Pd-catalyzed spiroannulation of 4-bromocoumarin with alkynes has been illustrated. The reaction highlights an interesting process for cascade formation of two five-membered rings through spiroannulation followed by cyclization via C-H activation. This method offers an attractive platform for the synthesis of a broad range of indane-fused spiropentadiene chromanones in good yields.

Transition-metal free C(sp2)-C(sp2) bond formation: arylation of 4-aminocoumarins using arynes as an aryl source.

A mild, efficient and transition-metal free synthetic strategy has been developed for the α-arylation of 4-aminocoumarins. This synthetic strategy proceeds via C(sp2)-C(sp2) bond formation between 4-aminocoumarins and aryne precursors in a single step by simple treatment with a fluoride source in the absence of a metal-catalyst. Moreover, this methodology affords good yields of 4-amino-3-arylcoumarin derivatives bearing halide functionality.

Three-Component Coupling Reactions of Aryne, DMSO, and Activated Alkyne: Stereoselective Synthesis of 2-[( o-Methylthio)aryloxy]-Substituted Dialkyl Maleates.

A transition-metal-free coupling reaction of aryne, DMSO, and activated alkyne for the synthesis of 2-[( o-methylthio)aryloxy]-substituted dialkyl maleates is reported. This cascade process is associated with several bond cleavage as well as bond formation reactions in one pot. One of our synthesized maleates has been unambiguously established by single-crystal XRD studies. This methodology allows preparation of trisubstituted vinyl ethers with excellent stereospecificity.

A cascade process for the synthesis of ortho-formyl allyl aryl ethers and 2H-chromen-2-ol derivatives from arynes via trapping of o-quinone methide with an activated alkene.

A transition-metal free synthetic strategy has been developed for the direct synthesis of ortho-formyl substituted allyl aryl ethers via a cascade three-component coupling of arynes, activated alkene and N,N-dimethylformamide. The reaction proceeds via C-O and C-C bond cleavage as well as C-C and two new C-O bond formations in a single reaction vessel. The methodology provides a good yield of ortho-formyl substituted allyl aryl ethers. Moreover, the synthetic strategy has been utilized for the one-pot synthesis of 2H-chromen-2-ol derivatives.

Synthesis of 1-Azaanthraquinone: Sequential C-N Bond Formation/Lewis Acid Catalyzed Intramolecular Cyclization Strategy.

A synthetic strategy has been developed for the synthesis of 1-azaanthraquinones. This synthetic protocol consists of sequential Pd-catalyzed carbon-nitrogen bond formation followed by Lewis acid catalyzed intramolecular cyclization. The Pd-catalyzed aminated intermediate was isolated and characterized. This sequential reactions strategy provides a wide range of 1-azaanthraquinones with good yields.