Enantioselective synthesis of spirocyclic cyclopentenes: asymmetric [3+2] annulation of 2-arylideneindane-1,3-diones with MBH carbonates derivatives catalyzed by multifunctional thiourea–phosphines

Indane-1,3-Dione: From Synthetic Strategies to Applications

Indane-1,3-dione is a versatile building block used in numerous applications ranging from biosensing, bioactivity, bioimaging to electronics or photopolymerization. In this review, an overview of the different chemical reactions enabling access to this scaffold but also to the most common derivatives of indane-1,3-dione are presented. Parallel to this, the different applications in which indane-1,3-dione-based structures have been used are also presented, evidencing the versatility of this structure.

Organocatalytic Regio- and Enantioselective [3 + 2]-Annulations of Ninhydrin-Derived Morita-Baylis-Hillman Carbonates with 3-Methyleneoxindoles

A type of Morita-Baylis-Hillman (MBH) carbonates has been developed from ninhydrin. These MBH carbonates have been successfully employed as 3C-synthons in the organocatalytic asymmetric [3 + 2]-annulations of the isatin-derived electron-deficient olefins, affording structurally diverse spirooxindoles in high yield with excellent stereoselectivity. In particular, the regioselectivity of MBH carbonates was controlled by the reaction partner, 3-methyleneoxindoles with carbonyl groups (R = ArCO), affording β-selective products and 3-methyleneoxindoles with ester groups (R = CO₂Me) furnishing γ-selective products. The representative scale-up reactions and transformation of product were examined. The reaction mechanism was expounded by control experiments.

[3+2] regioselective annulation reaction of 2-arylidene-1,3-indandiones towards synthesis of spirocyclopentenes: understanding the mechanism of γ-attack vs. α-attack using DFT studies

A regioselective [3+2] cyclisation reaction between 2-arylidene-1,3-indanedione and ethyl 2,3-butadienoate catalysed by triphenylphosphine has been demonstrated to synthesize functionalised spirocyclic cyclopentenes. The reaction tolerated various electron-rich and electron-deficient aryl substituted 2-arylidene-1,3-indanediones with high to excellent chemical yields (up to 99%) and moderate to good regioselectivity (up to 5 : 1). DFT studies have also been carried out to understand the regioselective nature of this reaction. The results of Frontier molecular orbital calculations and the activation energy (E a) favour the formation of compound 3avia γ-attack compared to that of 4avia α-attack.

Highly diastereoselective spiro-cyclopropanation of 2-arylidene-1,3-indanediones and dimethylsulfonium ylides

High diastereoselectivity, mild conditions and excellent functional group compatibility.

Annulations involving 2-arylidene-1,3-indanediones: stereoselective synthesis of spiro- and fused scaffolds

Stereoselective annulations of 2-arylidene-1,3-indanediones towards spiro-carbocycles as well as spiro/fused heterocycles based on various cycloadditions and tandem annulations are described.

Phosphine Organocatalysis

The hallmark of nucleophilic phosphine catalysis is the initial nucleophilic addition of a phosphine to an electrophilic starting material, producing a reactive zwitterionic intermediate, generally under mild conditions. In this Review, we classify nucleophilic phosphine catalysis reactions in terms of their electrophilic components. In the majority of cases, these electrophiles possess carbon-carbon multiple bonds: alkenes (section 2), allenes (section 3), alkynes (section 4), and Morita-Baylis-Hillman (MBH) alcohol derivatives (MBHADs; section 5). Within each of these sections, the reactions are compiled based on the nature of the second starting material-nucleophiles, dinucleophiles, electrophiles, and electrophile-nucleophiles. Nucleophilic phosphine catalysis reactions that occur via the initial addition to starting materials that do not possess carbon-carbon multiple bonds are collated in section 6. Although not catalytic in the phosphine, the formation of ylides through the nucleophilic addition of phosphines to carbon-carbon multiple bond-containing compounds is intimately related to the catalysis and is discussed in section 7. Finally, section 8 compiles miscellaneous topics, including annulations of the Hüisgen zwitterion, phosphine-mediated reductions, iminophosphorane organocatalysis, and catalytic variants of classical phosphine oxide-generating reactions.

Multifunctional chiral phosphine-catalyzed [3+2] annulation of Morita-Baylis-Hillman carbonates with cyclopentenones: asymmetric synthesis of 4-oxo-hexahydropentalenes

A multifunctional chiral phosphine-catalyzed enantioselective [3+2] annulation of Morita-Baylis-Hillman carbonates with cyclopentenones provides a direct approach to access functional 4-oxo-1,3a,4,5,6,6a-hexahydropentalene compounds. Moderate to good yields and excellent enantioselectivities (>90% ee) were obtained for a series of substrates under mild reaction conditions.

Recent advances in the annulation of Morita–Baylis–Hillman adducts

In this review, we summarize some of the most recent advances in the construction of cyclic compounds from the annulation of Morita–Baylis–Hillman (MBH) adducts, which have demonstrated their importance by possessing diverse functional groups.

Catalytic asymmetric Tamura cycloaddition of homophthalic anhydrides with 2-arylidene-1,3-diones

2-Arylidene-1,3-diones have been firstly employed in enantioselective Tamura cycloaddition to construct chiral spiro-1,3-indanedione derivatives.

Chiral bifunctional ferrocenylphosphine catalyzed highly enantioselective [3 + 2] cycloaddition reaction

The asymmetric [3 + 2] annulation catalyzed by air-stable (R,S_Fc)-N-acyl amino ferrocenylphosphines LB5 affords the bicyclic imides with 84–99% ee and 67–99% yield.

Formation of zwitterionic salts via three-component reaction of benzimidazolium bromides, aromatic aldehydes and 1,3-indanedione

The three-component reaction in ethanol in the presence of triethylamine as base catalyst resulted in the unusual charge-separated zwitterionic salts in good yields.

Recent developments in the synthesis and utilization of chiral β-aminophosphine derivatives as catalysts or ligands

In the last few years, the research area of chiral β-aminophosphines capable of promoting a wide range of diverse organic transformations has attracted more attention.

Phosphine-catalyzed highly enantioselective [3 + 3] cycloaddition of Morita-Baylis-Hillman carbonates with C,N-cyclic azomethine imines

The first phosphine-catalyzed highly enantioselective [3 + 3] cycloaddition of Morita-Baylis-Hillman carbonates with C,N-cyclic azomethine imines is described. Using a spirocyclic chiral phosphine as the catalyst, a novel class of pharmaceutically interesting 4,6,7,11b-tetrahydro-1H-pyridazino[6,1-a]iso-quinoline derivatives were obtained in high yields with good to excellent diastereoselectivities and extremely excellent enantioselectivities (98->99% ee).

Enantioselective construction of spiro-1,3-indandiones with three stereocenters via organocatalytic Michael-aldol reaction of 2-arylideneindane-1,3-diones and nitro aldehydes

Asymmetric domino reaction between 2-arylideneindane-1,3-dione and nitro aldehyde has been developed for the construction of an enantioenriched spiro-1,3-indandione framework with three stereocenters.

Construction of dispirocyclohexanes via amine-catalyzed [2 + 2 + 2] annulations of Morita–Baylis–Hillman acetates with exocyclic alkenes

Divergent amine-catalyzed [2 + 2 + 2] annulations of Morita–Baylis–Hillman acetates with exocyclic alkenes were developed for the convergent construction of multistereogenic dispirocyclohexanes.

Chiral phosphines in nucleophilic organocatalysis

This review discusses the tertiary phosphines possessing various chiral skeletons that have been used in asymmetric nucleophilic organocatalytic reactions, including annulations of allenes, alkynes, and Morita–Baylis–Hillman (MBH) acetates, carbonates, and ketenes with activated alkenes and imines, allylic substitutions of MBH acetates and carbonates, Michael additions, γ-umpolung additions, and acylations of alcohols.