Pd-Catalyzed Alkyne and Aryne Annulations: Synthesis and Photophysical Properties of π-Extended Coumarins.

A Pd-catalyzed alkyne and aryne annulation strategy via C-H activation has been implemented for the synthesis of π-extended coumarins. This synthetic strategy provides a wide range of π-extended coumarins in moderate to good yields with good functional group compatibility. Photophysical properties of the synthesized π-extended coumarins have been evaluated, and some of them show interesting fluorescent properties. Three of the synthesized coumarins have been unambiguously established by a single-crystal XRD study.

Access to diverse organosulfur compounds via arynes: a comprehensive review on Kobayashi's aryne precursor.

Arynes are highly reactive transient intermediates having enormous applications in organic synthesis. In the last three decades aryne chemistry has shown incredible developments in carbon-carbon and carbon-heteroatom bond formation reactions. After the discovery of Kobayashi's protocol for the generation of aryne intermediates in a mild way, this field of chemistry witnessed rapid growth in synthetic organic chemistry. One aspect of development in this field involves C-S bond formation under mild conditions which has a tremendous scope for the synthesis of various important organosulfur building blocks.

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.

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.

Direct synthesis of ortho-methylthio allyl and vinyl ethers via three component reaction of aryne, activated alkene and DMSO.

A synthetic strategy has been developed for the direct synthesis of ortho-methylthio allyl and vinyl ethers via three-component reaction of in situ generated aryne, activated alkene and DMSO. This reaction proceeds via several bond cleavage and bond formation processes in a single operation. Mechanistic studies reveal that DMSO served as both a methylthiolating agent and an oxygen source. This synthetic method provides a wide range of ortho-methylthio-substituted arenes in good yields.

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.

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.