Efficient construction of polycyclic chromans through 4-methylbenzenesulfonic acid mediated domino 1,6-addition/oxa-Mannich reaction of ortho-hydroxyphenyl substituted para-quinone methides and cyclic enamides

Construction of Oxygen- and Nitrogen-based Heterocycles from p-Quinone Methides

In the last few years, there has been an explosive growth in the area of para-quinone methide (p-QM) chemistry. This boom is actually due to the unique reactivity pattern of p-QMs, and also their remarkable synthetic applications. In fact, p-QMs serve as synthons for unsymmetrical diaryl- and triarylmethanes, and also for the construction of diverse range of carbocycles and heterocycles. In the last few years, a wide range of structurally complex heterocyclic frameworks could be accessed through the synthetic transformations of structurally modified stable p-QMs. Therefore, the main focus of this review article is to cover the recent advancements in the transition-metal, Lewis acid and base-catalyzed/mediated synthetic transformations of the stable p-quinone methides (p-QMs) to oxygen- and nitrogen-containing heterocycles.

Metal-Free, Acid-Catalyzed 1,6-Conjugate Addition of NH-Sulfoximines to para-Quinone Methides: Accessing to Diarylmethine Imino Sulfanone

We have reported an efficient and metal-free method for the construction of α-diarylmethine imino sulfanone using acid-catalyzed 1,6-conjugate addition of sulfoximines on para-quinine methides (p-QMs). This method showed broad functional group tolerance and a wide range of substrate scope with good to excellent yield. The excellent protocol exhibits mild reaction conditions with high atom economy. The practicability of the present method was supported by a Gram-scale reaction.

Chiral Thioureas-Preparation and Significance in Asymmetric Synthesis and Medicinal Chemistry

For almost 20 years, thioureas have been experiencing a renaissance of interest with the emerged development of asymmetric organocatalysts. Due to their relatively high acidity and strong hydrogen bond donor capability, they differ significantly from ureas and offer, appropriately modified, great potential as organocatalysts, chelators, drug candidates, etc. The review focuses on the family of chiral thioureas, presenting an overview of the current state of knowledge on their synthesis and selected applications in stereoselective synthesis and drug development.

Recent developments in 1,6-addition reactions of para-quinone methides (p-QMs)

In this review, we provide a comprehensive overview of recent progress in this rapidly growing field by summarizing the 1,6-conjugate addition and annulation reactions of p-QMs with consideration of their mechanisms and applications.

Facile synthesis of 9H-pyrrolo[1,2-a]indoles via Brønsted acid catalyzed cascade reactions

A Brønsted acid system promotes the Friedel–Crafts alkenylation/1,6-addition/condensation cascade reaction of ynones with indoles to access 9H-pyrrolo[1,2-a]indoles.