Fluoride-Mediated α-Selective 1,6-Conjugate Addition of Allenic Esters to p-Quinone Methides

Phosphine-catalyzed Rauhut-Currier reaction of γ-alkyl allenoate and subsequent trapping using the Diels-Alder reaction

We have disclosed a Rauhut-Currier reaction of γ-alkyl-substituted allenoate, catalyzed by L-valine-derived amide phosphine, to form trisubstitued allenoate, which was trapped by maleimide or DMAD via the Diels-Alder reaction. Exo-bicyclic succinimide derivatives including three continuous stereocenters with an exo-carbon-carbon double bound were constructed in up to quantitative yields with high stereospecificity.

V. K, Reddy VS. Regioselective Allenylation and Propargylation of Various para-Quinone Methides Using Alkynyl Azaarenes as Pronucleophile

We have developed a Brønsted base-mediated regioselective allenylation and propargylation of various para-quinone methides using unfunctionalized 2-alkynyl azaarenes as the pronucleophile. The appropriate choice of a base provides an opportunity...

Base-Mediated Intramolecular Cyclization of α-Nitroethylallenic Esters as a Synthetic Route to 5-Hydroxy-3-pyrrolin-2-ones

An unprecedented Cs₂CO₃-mediated intramolecular cyclization/rearrangement cascade that transforms α-nitroethylallenic esters to functionalized pyrrolin-2-ones has been uncovered. This reaction provides a new and practical approach for the synthesis of medicinally privileged 5-hydroxy-3-pyrrolin-2-ones under mild conditions. The broad potential of this new method was demonstrated by an efficient Au/Ag-catalyzed heteroarylation of 5-hydroxy-3-pyrrolin-2-ones employing electron-rich heteroarenes to furnish heteroaryl-lactam derivatives.

Catalyst-free 1,6-conjugate addition of indoles and 4-hydroxycoumarins to para-quinone methides: synthesis of unsymmetrical triarylmethanes

The catalyst-free 1,6-conjugate addition of indoles and 4-hydroxycoumarins to para-quinone methides is reported. This protocol allowed us to access a range of unsymmetrical triarylmethanes in good to excellent yields. The outlined procedure is operationally simple, efficient, atom and step economical. The synthesized heterocyclic triarylmethanes were further converted into highly substituted indoloisoquinolines and pyranochromenones via metal-catalyzed C-H activation/annulation.

Metal free highly efficient C–N bond formation through 1,6-addition: synthesis and photophysical studies of diaryl methyl amino acid esters (DMAAEs)

A transition-metal free, proficient strategy for the one-pot synthesis of diverse diaryl methyl amino acid esters (DMAAEs) has been established from the easily accessible chiral amino acid esters and para-quinone methides (QMs) in very good to excellent yields.

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.

Divergent synthesis of oxindole derivatives via controllable reactions of isatin-derived para-quinone methides with sulfur ylides

A catalyst-free and controllable reaction of isatin-derived para-quinone methides with sulfur ylides was developed, and it enables the divergent synthesis of two valuable oxindoles.

InCl3-catalyzed 5-exo-dig cyclization/1,6-conjugate addition of N-propargylamides with p-QMs to construct oxazole derivatives

An InCl₃-catalyzed tandem intramolecular 5-exo-dig cyclization/1,6-conjugate addition/aromatization of N-propargylamides with p-QMs to produce oxazoles tethering diarylmethane has been successfully developed.

Synthesis of indenofurans, benzofurans and spiro-lactones via Hauser–Kraus annulation involving 1,6-addition of phthalide to quinone methides

Base mediated 1,6-addition–Dieckmann cyclization of phthalide with quinone methide leads to oxygen heterocycles such as indenofurans, spiro-lactones and benzofurans through a cascade of rearrangements involving multiple ring opening and ring closure.

A [4 + 1] annulation of ortho-electrophile-substituted para-quinone methides for the synthesis of indanes and isoindolines

Indanes and isoindolines were obtained via a 1,6-conjugated addition/1,4-Michael addition of ortho-electrophile-substituted para-quinone methides with nucleophiles in high yields and with good functional group tolerance.

Metal-free, radical 1,6-conjugated addition of cyclic ethers with para-quinone methides (p-QMs)

An efficient method for metal-free C–C bond formation between p-quinone methides (p-QMs) and cyclic ethers via a radical pathway to afford substituted diarylmethanes and triarylmethanes or to effect the α-alkylation of the cyclic ethers has been developed.