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.

Two Cascade Processes Initiated by the Insertion of Benzyne into the Se═O Bond

Two sets of cascade processes have been realized, both of which were initiated with a benzyne insertion into the Se═O bond. The key factors to differentiate these processes are based on the structures of diaryl selenium oxides and reaction conditions. When diaryl selenium oxides containing an ortho weak σ-electron-withdrawing group were used, triarylselenonium salts were obtained at room temperature, while ortho-(aryloxy)phenyl phenyl selanes could be produced from diaryl selenium oxides at 100 °C.

Diverse Synthesis of Triarylselenonium Salts and o-(Alkoxy)aryl Aryl Selanes via Insertion of Benzyne into the Se═O Bond

An insertion of benzyne into the Se═O bond has been realized. In this reaction, two types of compounds containing selenium could be synthesized from different substrates. When diaryl selenium oxides were used, triarylselenonium salts were furnished, while o-(alkoxy)phenyl phenyl selanes could be produced from aryl alkyl selenium oxides.

Application of DMSO as a methylthiolating reagent in organic synthesis

In the past decades, DMSO has been widely used not only as a common solvent but also as an environmentally benign oxidant in various organic transformations. Most strikingly, DMSO can be used as a sulfur source to construct methylthiolated building blocks of potential biologically active molecules, which is a remarkable achievement in the field of organic sulfur chemistry. The purpose of this review article is to summarize and discuss the main developments in the application of DMSO as a methylthiolating reagent to introduce the -SMe functionality in organic synthesis.

Recent Advances in Construction of C(sp2)–O Bonds via Aryne Participated Multicomponent Coupling Reactions

Aryne chemistry is a powerful synthetic technique that forms new bonds to aromatic rings. The recent resurgence of aryne-based multicomponent coupling strategies has led to an influx of methodologies for the mild synthesis of arene derivatives. In particular, these innovative discoveries broaden and streamline approaches toward phenol ether motifs, which are a prevalent structural component across a broad range of chemistry related research fields. Herein, this review aims to provide a comprehensive overview of the recent progress in the construction of C(sp2)–O bonds via aryne-induced multicomponent reactions. Special attention has been paid to reaction design and mechanistic pathways.

1 Introduction

2 Insertion-Based MCRs

3 Nucleophilic-Addition-Based MCRs

4 Cycloaddition-Based MCRs

5 Summary

Recent Advance on Dimethyl Sulfoxide (DMSO) Used as a Multipurpose Reactant

Abstract:

Dimethyl sulfoxide (DMSO) is not only a common and cheap aprotic polar solvent with low toxicity, but also serves as an efficient and multipurpose reactant and has widely been used in organic synthesis. DMSO as an important precursor can effectively introducea broad range of functional fragments into organic molecules, such as -Me, -CH, -CH2, -SMe2, -CH2SMe, -CH2SOMe, -SMe, -SO2Me, -SOMe or as O substituents, and serves as a mild oxidant in organic transformations. Many significant achievements based on DMSO as a synthon in synthetic chemistry have rapidly made over the past several years. To help researchers further understand the recent advances in the field, the review summarizes the applications of DMSO as carbon, sulfur, and oxygen sources and is used as the dual synthon in synthetic transformations.

One-pot synthesis of 3-substituted-3-hydroxyindolin-2-ones: three component coupling of N-protected isatin, aryne precursor and 1,3-cyclodione under metal-free conditions

A transition-metal free synthetic strategy for the direct synthesis of 3-substituted-3-hydroxy-indolin-2-ones via three component coupling of N-protected isatin, aryne precursor, and 1,3-cyclodione.

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.

Diverse diaryl sulfide synthesis through consecutive aryne reactions

An efficient method to synthesize diaryl sulfides with structural diversity is disclosed. Demethylative hydrothiolation of aryne intermediates generated from o-iodoaryl triflates with methylthio-substituted o-silylaryl triflates and further aryne reactions afford diverse diaryl sulfides.

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).

Phenanthrenes/dihydrophenanthrenes: the selectivity controlled by different benzynes and allenes

A method for the intermolecular annulation of benzynes with allenes is disclosed. This protocol utilized allenes as an unconventional diene component for the selective synthesis of phenanthrenes and dihydrophenanthrenes under the control of different benzyne precursors, featuring high atom-economy and good functional group compatibility. Density functional theory (DFT) calculations reveal that different migratory routes of the aromatic C-H bond are crucial for the observed selectivity.

One-step synthesis of benzo[b]thiophenes by aryne reaction with alkynyl sulfides

An aryne reaction with alkynyl sulfides affording benzo[b]thiophenes is disclosed. A wide range of 3-substituted benzothiophenes were synthesized from easily available o-silylaryl triflates and alkynyl sulfides in a one-step intermolecular manner. The synthesis of diverse multisubstituted benzothiophene derivatives involving a pentacyclic compound was achieved by virtue of the good functional group tolerance and versatile C2 functionalizations.

C–O/C–S difunctionalized benzene derivatives via multicomponent coupling of tetraynes

C–O/C–S difunctionalization of fused highly substituted benzene derivatives was conducted via the multicomponent coupling reaction of tetraynes, sulfoxides, and cyclopropenones.

Synthesis of 6-substituted indoloquinazolinones from arynes and 2-acyl-4-quinazolinones: a transition-metal free C–N and C–C bond formation strategy

A versatile transition-metal free synthetic strategy has been developed for the direct synthesis of 6-substituted indoloquinazolinones from 2-acyl-4-quinazolinones and aryne precursors. This cascade strategy proceeds via successive C–N and C–C bond formation in a single reaction vessel.