Asymmetric Total Synthesis of Naturally Occurring (R)-2'-Methoxydihydroartemidin, (R)-(E)-3'-Hydroxyartemidin, and Its Structural Congeners: Method Optimization and Mechanistic Analysis

Asymmetric total synthesis of naturally occurring 3-substituted isocoumarins, 2'-methoxydihydroartemidin, (E)-3'-hydroxyartemidin, and two structural congeners is reported in this article. Enantiopure 3-alkylisocoumarin core present in those target molecules was accessed through an atom-economical and regiodefined 6-endo-dig cyclization from properly substituted 2-halobenzoic acids and chiral terminal alkynes through ligand-free Cu(I) catalysis. A detailed mechanistic investigation was carried out through control experiments, and density functional theory (DFT) analysis reveals that solvent directed a non-Sonogashira pathway through direct insertion of alkyne through a regiodefined way is operating. The synthesized 3-alkylisocoumarins are synthetically manipulated into various small molecular entities.

Metallaelectro-catalyzed alkyne annulations via C-H activations for sustainable heterocycle syntheses

Alkyne annulation represents a versatile and powerful strategy for the assembly of structurally complex compounds. Recent advances successfully enabled electrocatalytic alkyne annulations, significantly expanding the potential applications of this promising technique towards sustainable synthesis. The metallaelectro-catalyzed C-H activation/annulation stands out as a highly efficient approach that leverages electricity, combining the benefits of electrosynthesis with the power of transition-metal catalyzed C-H activation. Particularly attractive is the pairing of the electro-oxidative C-H activation with the valuable hydrogen evolution reaction (HER), thereby addressing the growing demand for green energy solutions. Herein, we provide an overview of the evolution of electrochemical C-H annulations with alkynes for the construction of heterocycles, with a topical focus on the underlying mechanism manifolds.

Cascade Oxypalladation/1,3-Palladium Shift to Access Cyclopentene-Fused Isocoumarins

Fused isocoumarins are frequently found in several natural products and pharmaceuticals. Herein, a cascade annulation of 2-alkynylbenzoate-tethered cyclic 1,3-diones via sequential trans-oxypalladation, carbonyl insertion, 1,3-Pd shift, and β-hydride elimination is reported. This method provides efficient access to highly diastereoselective tetracyclic cyclopentene-fused isocoumarins containing two contiguous quaternary stereocenters. A plausible reaction mechanism is proposed on the basis of mechanistic studies, including deuterium labeling experiments. Studies toward enantioselective synthesis using a chiral Bpy ligand gave encouraging initial results.

Regioselective Annulation of 6-Carboxy-Substituted Pyrones as a Two-Carbon Unit in Formal [4 + 2] Cycloaddition Reactions

Heterocycles serve as a critical motif in chemistry, but despite being present in more than 85% of pharmaceuticals, there are limited methods for their construction. Here, we describe the incorporation of intact pyrone (2H-pyran-2-one) into larger ring systems via annulation. In a formal [4 + 2] cycloaddition, the pyrone regioselectively accepts a benzylic anion as a nucleophile in a conjugate addition fashion, with the subsequent pyrone-derived enolate attaching to a pendant ester on the initial nucleophile. Subsequent base-driven enolate formation and elimination establish aromaticity of the newly formed ring. After optimization of this process using an NMR-based assessment to overcome solubility and separation challenges, the reaction was successfully applied to a library of 6-ester and -amide-substituted pyrones and using a phenyl ester and other substituted sulfoxides. This technology enables the incorporation of intact pyrone rings into more complex systems, such as for the total synthesis of the natural product thermorubin.

Regioselective Synthesis of 3-Substituted Isocoumarin-1-imines via Palladium-Catalyzed Denitrogenative Transannulation of 1,2,3-Benzotriazin-4(3H)-ones and Terminal Alkynes

A palladium-catalyzed denitrogenative transannulation strategy to access various 3-substituted isocoumarin-1-imine frameworks using 1,2,3-benzotriazin-4(3H)-ones and terminal alkynes is described. The reaction is highly regioselective and tolerates a wide range of functional groups. The reaction is believed to proceed via a five-membered palladacycle intermediate extruding environmentally benign molecular nitrogen as a by-product. The utility of this method was showcased through the one-pot synthesis of biologically relevant 3-substituted isocoumarin scaffolds.

Activation of a Silent Polyketide Synthase SlPKS4 Encoding the C7-Methylated Isocoumarin in a Marine-Derived Fungus Simplicillium lamellicola HDN13-430

Coumarins, isocoumarins and their derivatives are polyketides abundant in fungal metabolites. Although they were first discovered over 50 years ago, the biosynthetic process is still not entirely understood. Herein, we report the activation of a silent nonreducing polyketide synthase that encodes a C7-methylated isocoumarin, similanpyrone B (1), in a marine-derived fungus Simplicillium lamellicola HDN13-430 by heterologous expression. Feeding studies revealed the host enzymes can change 1 into its hydroxylated derivatives pestapyrone A (2). Compounds 1 and 2 showed moderate radical scavenging activities with ED50 values of 67.4 µM and 104.2 µM. Our discovery fills the gap in the enzymatic elucidation of naturally occurring C7-methylated isocoumarin derivatives.

Copper-Promoted Intramolecular Oxidative Dehydrogenation for Synthesizing Dihydroisocoumarins and Isocoumarins

Isocoumarins and dihydroisocoumarins are important skeletons with a wide range of biological activities, such as anti-bacterial, anti-allergy, anti-fungal, anti-tumor, and anti-HIV properties. Herein, we demonstrated divergent syntheses of isocoumarins and 3,4-dihydroisocoumarins by intramolecular dehydrogenative cyclization of 2-(3-oxobutyl) benzoic acids. This transformation undergoes Csp3-H bonds and O-H bonds coupling in air using copper salt. The reactions may undergo free radical process.

Straightforward Synthesis of Bis[(trifluoromethyl)sulfonyl]ethylated Isocoumarins from 2-Ethynylbenzoates

Herein, we report a facile isocoumarin and isoquinolone preparation by taking advantage of an initial bis(triflyl)ethylation [triflyl = (trifluoromethyl)sulfonyl] reaction, followed by heterocyclization, which contrasts with our previous results on cyclobutene formation. The efficiency of the catalyst- and irradiation-free heterocyclization/bis(triflyl)ethylation sequence showed exquisite dependence on the electronic nature of the substituents at the 2-ethynylbenzoate(benzamide) precursors. Molecular docking of model bis(triflyl)ethylated isocoumarins on human acetylcholinesterase (hAChE) revealed promising biological activities through selective coordination on both the catalytic active site and peripheral active site.

Recent advances in the discovery, biosynthesis, and therapeutic potential of isocoumarins derived from fungi: a comprehensive update

Microorganisms still remain the main hotspots in the global drug discovery avenue. In particular, fungi are highly prolific producers of vast structurally diverse specialized secondary metabolites, which have displayed a myriad of biomedical potentials. Intriguingly, isocoumarins is one distinctive class of fungal natural products polyketides, which demonstrated numerous remarkable biological and pharmacological activities. This review article provides a comprehensive state-of-the-art over the period 2000-2022 about the discovery, isolation, classifications, and therapeutic potentials of isocoumarins exclusively reported from fungi. Indeed, a comprehensive list of 351 structurally diverse isocoumarins were documented and classified according to their fungal sources [16 order/28 family/55 genera] where they have been originally discovered along with their reported pharmacological activities wherever applicable. Also, recent insights around their proposed and experimentally proven biosynthetic pathways are also briefly discussed.

Efficient Synthesis of 1H-Benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-one Derivatives Using Ag2CO3/TFA-Catalyzed 6-endo-dig Cyclization: Reaction Scope and Mechanistic Study

A small library of 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-one derivatives was prepared in good to excellent yields, involving a Ag₂CO₃/TFA-catalyzed intramolecular oxacyclization of N-Boc-2-alkynylbenzimidazole substrates. In all experiments, the 6-endo-dig cyclization was exclusively achieved since the possible 5-exo-dig heterocycle was not observed, indicating the high regioselectivity of this process. The scope and limitations of the silver catalyzed 6-endo-dig cyclization of N-Boc-2-alkynylbenzimidazoles as substrates, bearing various substituents, were investigated. While ZnCl₂ has shown limits for alkynes with an aromatic substituent, Ag₂CO₃/TFA demonstrated its effectiveness and compatibility regardless of the nature of the starting alkyne (aliphatic, aromatic or heteroaromatic), providing a practical regioselective access to structurally diverse 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-ones in good yields. Moreover, the rationalization of oxacyclization selectivity in favor of 6-endo-dig over 5-exo-dig was explained by a complementary computational study.

Direct Synthesis of 3-Aryl Substituted Isocoumarins and Phthalides through Palladium Acetate Catalyzed C(sp2 )-H Activation in Ionic Liquids

A novel Pd-catalysed oxidative coupling between benzoic acids and vinylarenes or acrylates to furnish isocoumarins and phthalides is reported. The reaction proceeds smoothly in molten tetrabutylammonium acetate via a selective C-H bond activation, with very low percentage of ligand-free palladium acetate as the catalyst, under atmospheric pressure of oxygen. Sub-stoichiometric amount of copper acetate is also required as a reoxidant for the palladium.

Design, development and applications of copper-catalyzed regioselective (4 + 2) annulations between diaryliodonium salts and alkynes

Diaryliodonium salts have been extensively applied in organic synthesis as aryl cation equivalents. However, in the electrophilic reactions with alkenes or alkynes, only the electrophilic carbon of the diaryliodonium salts was involved while the other part of the aryl ring was not utilized. Herein, a reaction pattern of diaryliodonium was reported as oxa-1,4-dipoles to undergo (4 + 2) cycloaddition reactions with alkynes. Broad spectrum of the two reaction partners could be utilized in this protocol, enabling an operationally simple, high yielding, and regioselective synthetic approach to isocoumarins. Particularly, good to excellent regioselectivities were achieved for the sterically unbiased unsymmetrical diaryl acetylenes, which was challenging for other transition metal-catalyzed processes. The reaction could be scaled up with the ideal 1:1 stoichiometry and the isocoumarin type natural products Oospolactone and Thunberginol A could be obtained in one or three steps through this methodology.

Modular Regiodivergent Synthesis of Benzo-Fused Isocoumarins by a Cyclopropane Aromatization Strategy

Reported herein is an electrophile-modulated aromatization reaction of highly functionalized cyclopropanes to structurally diverse benzoisocoumarins featuring concurrent formation of the benzenoid and α-pyrone rings under mild conditions. An aromatization reaction of the proposed benzonorcaradiene intermediates prepared independently revealed a crucial role of the neighboring olefinic substituents in determining whether the cyclopropane ring expansion is followed by a 1,2-shift of the ester group.

FeCl3-Catalyzed Synthesis of Tanshinlactone Analogues from 1H-Indene-1,2,3-triones and Alkynes

Tanshinlactone has been found in several natural products and biologically active compounds. Herein, a new FeCl₃-catalyzed strategy using 1H-indene-1,2,3-triones and alkynes as starting materials is reported to obtain various tanshinlactone derivatives. This protocol has the advantages of involving low cost, environmentally benign catalysts, simple reaction conditions, and a broad range of substrates.

3-Amino-4-(diphenylamino)-1H-2-benzopyran-1-one

Various synthetic methodologies to obtain 3,4-diaminoisocumarin nucleus have been reported and described. However, mechanistic analysis based on experimental evidence is lacking. Herein, we report the synthesis of the novel 3-amino-4-(diphenylamino)-1H-2-benzopyran-1-one using a two-step methodology with a new mechanistic proposal to explain the formation of the latter based on previously reported precursors and the established conditions. This compound was afforded in 80% yield.

Dearomative Iodocyclization of N-(o-Alkynyl)aryl Isoindole

We present a dearomative iodocyclization of N-(o-alkynyl)aryl isoindole here, which affords various biologically active benzoindoleazine skeletons containing alkenyl iodine. The products can further undergo cycloaddition or coupling reactions to afford a series of highly functionalized N-fused polycyclic scaffolds.

Ru(II)- or Rh(III)-Catalyzed Annulation of Aromatic/Vinylic Acids with Alkylidenecyclopropanes via C-H Activation

An efficient and new route for the synthesis of (E)-4-benzylideneisochroman-1-ones through tandem cascade annulation of benzoic acids with alkylidenecyclopropanes using Ru(II) as a catalyst is demonstrated. It is important to note that the reaction delivers selectively E-stereoselective 4-benzylideneisochroman-1-one derivatives in moderate to good yields, which has completely diverse selectivity as compared with previous methods. Further, the annulation was explored with less-reactive β C-H activation of vinylic acids with alkylidenecyclopropanes, leading to the highly useful α-pyrone derivatives in the presence of an Rh(III) catalyst.

A Ag2CO3/TFA-catalyzed intramolecular annulation approach to imidazo[1,2-c][1,3]oxazin-5-one derivatives

A series of 2,7-disubstituted 3-methylimidazo[1,2-c][1,3]oxazin-5-ones were synthesized in good yields via Ag₂CO₃/TFA-mediated intramolecular annulation of N-Boc-2-alkynyl-4-bromo(alkynyl)-5-methylimidazoles. This methodology was carried out in the presence of a catalytic amount of silver carbonate and trifluoroacetic acid in dichloroethane at 60 °C. In all experiments, only the six-membered ring product was obtained since the possible five-membered compound was not observed, proving the high regioselectivity of this approach. A complementary computational study was performed in order to rationalize the mechanism of 6-endo-dig heterocycle formation. In addition, 2-bromo-3-methyl-7-phenylimidazo[1,2-c][1,3]oxazin-5-one was used as a building block to synthesize a small library of new 2-substituted imidazo[1,2-c][1,3]oxazin-5-one derivatives through the Suzuki, Sonogashira and Heck cross coupling reactions.

Ru(II)-Catalyzed C-H Bond Activation/Annulation of N-iminopyridinium Ylides with Sulfoxonium Ylides

A Ru(II)-catalyzed C-H bond activation/annulation of N-iminopyridinium ylides with sulfoxonium ylides has been developed for the synthesis of diverse functionalized isocoumarin derivatives. This method features broad substrate scope, high-functional-group tolerance,...

Discovery of Natural Product Inspired 3-Phenyl-1H-isochromen-1-ones as Highly Potent Antioxidant and Antiplatelet Agents: Design, Synthesis, Biological Evaluation, SAR and in silico Studies

BACKGROUND

Several natural/synthetic molecules having structure similar to 1H-isochromen-1-ones have been reported to display promising antioxidants and platelet aggregation inhibitory activity. Isocoumarin (1H-2-benzopyran-1-one) skeleton, either whole or as a part of molecular framework, have been explored for their antioxidant or antiplatelet activities.

INTRODUCTION

Based on literature, a new prototype i.e., 3-phenyl-1H-isochromen-1-ones based compounds have been rationalized to possess both antioxidant as well as antiplatelet activities. Consequently, no reports are available regarding its inhibition either by cyclooxygenase-1 (COX-1) enzyme or by arachidonic acid (AA)-induced platelet aggregation. This prompted us to investigate 3-phenyl-1H-isochromen-1-ones towards antioxidant and antiplatelet agents.

METHODS

The goal of this work to identify new 3-phenyl-1H-isochromen-1-ones based compounds via synthesis of a series of analogues and performing in vitro antioxidant as well as AA-induced antiplatelet activities and then, identification of potent compounds by SAR and molecular docking studies.

RESULTS

Out of all synthesized 3-phenyl-1H-isochromen-1-ones analogues, five compounds showed 7-folds to 16-folds highly potent antioxidant activities than ascorbic acid. Altogether, ten 3-phenyl-1H-isochromen-1-one analogues displayed antioxidant activities in 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Almost, all the 3-phenyl-1H-isochromen-1-one analogues exhibited potent AA-induced antiplatelet activity; few of them displayed 7-folds more activity as compared to aspirin. Further, in silico analysis validated the wet results.

CONCLUSION

We disclose the first detailed study for the identification of 3-phenyl-1H-isochromen-1-one analogues as highly potent antioxidant as well as antiplatelet agents. The article describes the scaffold designing, synthesis, bioevaluation, structure-activity relationship and in silico studies of pharmaceutically privileged bioactive 3-phenyl-1H-isochromen-1-one class of heterocycles.

Synthesis of 4-Selanyl- and 4-Tellanyl-1H-isochromen-1-ones Promoted by Diorganyl Dichalcogenides and Oxone

A new method was developed for the synthesis of 4-chalcogenyl-1H-isochromen-1-ones through the 6-endo-dig electrophilic cyclization of 2-alkynylaryl esters and diorganyl dichalcogenides under ultrasound irradiation. The reactions were performed under mild conditions, using Oxone as a green oxidant to promote the cleavage of the chalcogen-chalcogen bond in diorganyl diselenides and ditellurides to generate electrophilic species in situ. A total of 25 compounds were selectively obtained after 30-70 min, in good to excellent yields (74-95%). This procedure was extended to prepare 5H-selenopheno[3,2-c]isochromen-5-ones. Additionally, for the first time, the 4-chalcogenyl-1H-isochromen-1-ones were used as substrates in the thionation reaction, using Lawesson's reagent and microwave irradiation under solvent-free conditions, obtaining the thio derivatives in yields of up to 99% in only 15 min.

Modular synthesis of 3-substituted isocoumarins via silver-catalyzed aerobic oxidation/6-endo heterocyclization of ortho-alkynylbenzaldehydes

A method involving silver-catalyzed aerobic oxidation/6-endo heterocyclization of ortho-alkynylbenzaldehydes to yield 3-substituted isocoumarins is described. The developed protocol allows convenient access to a range of synthetically useful 3-substituted isocoumarins and related fused heterocyclolactones in good to high yields, using silver tetrafluoroborate as the catalyst, and atmospheric oxygen as the terminal oxidant and the source of endocyclic oxygen. Mechanistic studies suggest the involvement of a free-radical pathway.

Aminium cation-radical catalysed selective hydration of (E)-aryl enynes

The hydration of carbon-carbon triple bonds is an important and atom economic synthetic transformation. Herein, we report a mild and selective method for the catalytic Markovnikov hydration of (E)-aryl enynes to the corresponding enones, mediated through the bench-stable aminium salt, tris(4-bromophenyl)ammoniumyl hexachloroantimonate (TBPA). The chemoselective and diastereoselective method proceeds under neutral metal-free conditions, delivering excellent product yields from terminal and internal alkyne units. The synthesis of biologically important (E)-3-styrylisocoumarins, including a formal synthesis of the natural product achlisocoumarin III, demonstrates the utility of this novel transformation.

Enantioselective Synthesis of Fused Isocoumarins via Palladium-Catalyzed Annulation of Alkyne-Tethered Malononitriles

An enantioselective palladium-catalyzed annulation of alkyne-tethered malononitriles for the synthesis of 3,4-ring-fused isocoumarins is described. This cascade strategy involves oxypalladation of ortho-alkynylbenzoates and desymmetrizing addition onto one cyano group of the pendant malononitriles, which enables the concurrent construction of two rings and an all-carbon quaternary stereocenter in a single operation.

Visible-Light Photoredox Catalyzed Dehydrogenative Synthesis of Allylic Carboxylates from Styrenes

The visible-light photoredox/[Co(III)] cocatalyzed dehydrogenative functionalization of cyclic and acyclic styryl derivatives with carboxylic acids is documented. The methodology enables the chemo- and regioselective allylic functionalization of styryl compounds, leading to allylic carboxylates (32 examples) under stoichiometric acceptorless conditions. Intermolecular as well as intramolecular variants are documented in high yields (up to 82%). A mechanistic rationale is also proposed on the basis of a combined experimental and spectroscopic investigation.

Indium-Catalyzed C-F Bond Transformation through Oxymetalation/β-Fluorine Elimination to Access Fluorinated Isocoumarins

Fluorinated heterocycles have attracted much attention in the pharmaceutical and agrochemical industries. Many strategies have already been developed to achieve the synthesis of fluorinated heterocycles. Formidable challenges remain, however, in the synthesis of fluorinated isocoumarin derivatives that are among the most alluring structural motifs. Herein, the indium-catalyzed C-F bond transformation of 2-(2,2-difluorovinyl) benzoates is reported, which are readily accessible compounds, to give a diverse array of fluorinated isocoumarins. The present reaction proceeds smoothly using inexpensive reagents: a catalytic amount of indium salt in the presence of zinc salt. A theoretical calculation of potential energy profiles showed that the reaction consists of oxymetalation with the elimination of alkyl halide and the β-fluorine elimination.

Straightforward Functionalization of Sulfur-Containing Peptides via 5- and 6-endo-dig Cyclization Reactions

We present a simple and convenient method for the generation of sulfenyl electrophiles from peptides containing S–S or S–H bonds by employing N-chlorosuccinimide. The corresponding sulfenyl electrophiles are further utilized in 5- and 6-endo-dig cyclization reactions yielding indolizinium salts, indoles, benzo[b]furans, polyaromatic hydrocarbons (PAHs) and isocoumarins, as well as quinolinones bearing a glutathione moiety. PAH derivatives can be used as selective fluorescent dyes for the visualization of lipid droplets in living cells.

Natural isocoumarins: Structural styles and biological activities, the revelations carry on …

Isocoumarins and dihydroisocoumarins are lactonic phytochemicals plentiful in microbes and higher plants. These are an amazing small scaffolds consecrated with all types of pharmacological applications. Our previous review covered the period 2000-2016, documenting the then known natural products of this class; the current article is a critical account of discovery of known as well as undescribed structural types and pharmacological activities reported in the course of 2016-2020. The classification revealed in our previous review based on the biogenetic origin is further buttressed by discovery of new members of each class and some new structural types hitherto unknown have also been identified. Similarly, the biological activities and SAR conclusions identified were found to be valid as well, nonetheless with new accompaniments. The most recent available literature on the structural diversity and biological activity of these natural products has been included. The information documented in this article are collected from scientific journals, books, electronic search engines and scientific databases.

Cross-Dehydrogenative Coupling/Annulation of Arene Carboxylic Acids and Alkenes in Water with Ruthenium(II) Catalyst and Air

A cross-dehydrogenative coupling of arene carboxylic acids with olefins is reported with ruthenium(II) catalyst employing air and water as green oxidant and solvent, respectively. It offers a robust synthesis of valuable phthalide molecules. A one-pot sequential strategy is also disclosed to access Heck-type products that are apparently difficult to make directly from arene carboxylic acids.

Concise Synthesis of Isocoumarins through Rh-Catalyzed Direct Vinylene Annulation: Scope and Mechanistic Insight

Transition-metal-catalyzed activation of inert C-H bonds and subsequent C-C bond formation have emerged as powerful synthetic tools for the synthesis of elaborate cyclic molecules. In this report, we introduce an efficient synthetic method of 3,4-unsubstituted isocoumarins adopting an electron-deficient Cp^ERh complex as the catalyst. The use of vinylene carbonate as a vinylene transfer reagent enables the direct construction of isocoumarins from readily available benzoic acids, without any external oxidants as well as bases. The reaction mechanism is evaluated by computational analysis to find an unprecedented "rhodium shift" event within the catalytic cycle.

An Indirect Strategy for Trifluoromethylation via an Iridium Catalyst: Approach to Generate Isocoumarin Skeletons in Bioactive Molecules

3-Bromo-1,1,1-trifluoroacetone was first disclosed as an effective indirect trifluoromethylation reagent to construct the important 3-trifluoromethyl isocoumarin skeleton. The reaction proceeds through a ligand-promoted, iridium-catalyzed ortho-selective C-H alkylation of benzoic acid and an intermolecular cyclization reaction promoted by silver acetate. A wide range of 3-trifluoromethyl isocoumarins can be easily obtained in moderate to good yields. Importantly, the isocoumarin skeleton can be easily formed in bioactive compounds, highlighting the importance of this reaction.

α-Angelica lactone catalyzed oxidation of benzylic sp3 C-H bonds of isochromans and phthalans

A metal-free organocatalytic system has been developed for highly efficient benzylic C-H oxygenations of cyclic ethers using oxygen as an oxidant. This oxidation reaction utilizes α-angelica lactone as a low cost/low molecular weight catalyst. The optimized reaction conditions allow the synthesis of valued isocoumarins and phthalides from readily available precursors in good yields. Mechanistic studies indicate that the reaction pathway likely involves a radical process via a peroxide intermediate.

Enantioselective synthesis of indanone spiro-isochromanone derivatives via a dinuclear zinc-catalyzed Michael/transesterification tandem reaction

An enantioselective Michael/transesterification tandem reaction of α-hydroxy indanones with ortho-ester chalcones was realized using dinuclear zinc catalysts. A series of enantiomerically pure spiro[indanone-2,3'-isochromane-1-one] derivatives were obtained in good yields with excellent stereoselectivities (up to >20 : 1 dr, up to >99% ee). This protocol could be conducted on a gram scale without affecting its stereoselectivities. In addition, the absolute stereochemistry of the products was determined by X-ray crystallographic analysis of 3ac, and a positive nonlinear effect was observed. Finally, a possible catalytic cycle was proposed to explain the origin of the enantioselectivity.