Enantioselective Synthesis of 2,3-Disubstituted Indanones via Pd-Catalyzed Intramolecular Asymmetric Allylic Alkylation of Ketones

Organophosphates as Versatile Substrates in Organic Synthesis

This review summarizes the applications of organophosphates in organic synthesis. After a brief introduction, it discusses cross-coupling reactions, including both transition-metal-catalyzed and transition-metal-free substitution reactions. Subsequently, oxidation and reduction reactions are described. In addition, this review highlights the applications of organophosphates in the synthesis of natural compounds, demonstrating their versatility and importance in modern synthetic chemistry.

Insight into Stereocontrol in the Asymmetric Intramolecular Allylation with a tert-Butylsulfinamide Nucleophile: Application in the Synthesis of Chiral Isoindoline-1-Carboxylic Acid Esters

The asymmetric induction afforded by a chiral sulfinyl group in a palladium/Brønsted-acid-catalyzed intramolecular allylic amination was investigated. Predictions of the diastereoselectivity for various substrates under assumed total thermodynamic control were obtained from density functional theory (DFT), and the correlation with experimental data demonstrates abrupt changes to kinetic control across the substrate scope. The resulting heterocyclic product was readily converted to valuable isoindoline-1-carboxylic acid esters by a two-step oxidation sequence, providing asymmetric access to a key unnatural α-amino acid scaffold.

Palladium-Catalyzed Asymmetric Decarboxylative Addition of β-Keto Acids to Heteroatom-Substituted Allenes

The Pd-catalyzed asymmetric addition reaction of β-keto acids to heteroatom-substituted allene is reported. This reaction generates β-substituted ketones in an asymmetric manner through a branch-selective decarboxylative allylation pathway. The reaction accommodates various alkoxyallenes as well as amidoallenes.

Palladium/Brønsted-Acid-Catalyzed Diastereoselective Cyclization with Chiral Sulfinamides as Nucleophiles

This article reports diastereoselective cyclization with chiral sulfinamides as nucleophiles in two reaction pathways: (1) intramolecular allylic substitution and (2) sequential aerobic oxidation with aza-Michael addition. These reactions were enabled by synergistic palladium and Brønsted acid catalysis and produced chiral isoindolines with good yields of 55-92% and high diastereoselectivities of 10:1 to >20:1 dr.

Catalytic Enantioselective Alkylation of Prochiral Enolates

The asymmetric alkylation of enolates is a particularly versatile method for the construction of α-stereogenic carbonyl motifs, which are ubiquitous in synthetic chemistry. Over the past several decades, the focus has shifted to the development of new catalytic methods that depart from classical stoichiometric stereoinduction strategies (e.g., chiral auxiliaries, chiral alkali metal amide bases, chiral electrophiles, etc.). In this way, the enantioselective alkylation of prochiral enolates greatly improves the step- and redox-economy of this process, in addition to enhancing the scope and selectivity of these reactions. In this review, we summarize the origin and advancement of catalytic enantioselective enolate alkylation methods, with a directed emphasis on the union of prochiral nucleophiles with carbon-centered electrophiles for the construction of α-stereogenic carbonyl derivatives. Hence, the transformative developments for each distinct class of nucleophile (e.g., ketone enolates, ester enolates, amide enolates, etc.) are presented in a modular format to highlight the state-of-the-art methods and current limitations in each area.

Recent Advances in Enantioselective Pd-Catalyzed Allylic Substitution: From Design to Applications

This Review compiles the evolution, mechanistic understanding, and more recent advances in enantioselective Pd-catalyzed allylic substitution and decarboxylative and oxidative allylic substitutions. For each reaction, the catalytic data, as well as examples of their application to the synthesis of more complex molecules, are collected. Sections in which we discuss key mechanistic aspects for high selectivity and a comparison with other metals (with advantages and disadvantages) are also included. For Pd-catalyzed asymmetric allylic substitution, the catalytic data are grouped according to the type of nucleophile employed. Because of the prominent position of the use of stabilized carbon nucleophiles and heteronucleophiles, many chiral ligands have been developed. To better compare the results, they are presented grouped by ligand types. Pd-catalyzed asymmetric decarboxylative reactions are mainly promoted by PHOX or Trost ligands, which justifies organizing this section in chronological order. For asymmetric oxidative allylic substitution the results are grouped according to the type of nucleophile used.

Regio- and diastereoselective synthesis of trans-3,4-diaryldihydrocoumarins via metal-free [4+2] annulation of ynamides with o-hydroxybenzyl alcohols

An efficient regio- and diastereoselective method for the construction of valuable trans-3,4-diaryldihydrocoumarins via metal-free [4+2] annulation of ynamides with o-hydroxybenzyl alcohols has been developed. Ynamides are first treated as 2-π partners to react with o-hydroxybenzyl alcohols via traceless sulfonamide directing groups, affording trans-3,4-diaryldihydrocoumarins in good yields with high regio- and diastereoselectivities. This metal-free methodology is also characterized by a wide substrate scope, good functional group tolerance, and efficiency on a gram scale.

Dinuclear zinc synergistic catalytic asymmetric phospha-Michael/Michael cascade reaction: synthesis of 1,2,3-trisubstituted indanes bearing phosphoryl groups

A new dinuclear zinc synergistic catalytic asymmetric phospha-Michael/Michael cascade reaction of o-dienones and dialkyl phosphates is reported. This method has been proven to be general and efficient for the formation of a range of chiral 1,2,3-trisubstituted indane compounds containing phosphorus groups in good yields (up to 92%) with excellent stereoselectivities (up to >99% ee and up to >99 : 1 dr). The relative configuration of the product was identified as having a trans,trans substitution pattern via two-dimensional (2D) nuclear Overhauser effect spectroscopy 1H-1H NMR experiments. A possible mechanism was proposed.

Asymmetric Syntheses of Amaryllidaceae Alkaloids (-)-Crinane and (+)-4a-Dehydroxycrinamabine

A palladium-catalyzed asymmetric allyl-allyl cross-coupling reaction to construct the chiral quaternary carbon center of crinane alkaloids has been developed. On the basis of an efficient approach, the enantioselective synthesis of (-)-crinane (1) is presented, and the first asymmetric total synthesis of (+)-4a-dehydroxycrinamabine (2) was achieved by subsequent oxidation, 1,4-conjugate addition, RCM reaction, reductive amination, and Pictet-Spengler reaction. The method provided an alternative strategy for the syntheses of crinane alkaloids and other Amaryllidaceae natural products.

A rhodium-catalyzed tandem reaction of N-sulfonyl triazoles with indoles: access to indole-substituted indanones

Rhodium(ii)-catalyzed tandem reaction of N-sulfonyl triazoles with indoles delivered structurally diverse indole-substituted indanones bearing vicinal quaternary carbon centers.

Copper-catalyzed acyltrifluoromethylation of alkenes: rapid access to trifluoroethyl indanones and related compounds

Copper-catalyzed acyltrifluoromethylation of alkenes is described, affording trifluoroethyl indanones and related cyclic ketones in promising yields with excellent diastereoselectivity.

Enantioselective syntheses of indanes: from organocatalysis to C–H functionalization

The indanyl core is ubiquitous in a large variety of drugs and natural products. Remarkable recent progress has been accomplished in the step-economical assembly of functionalization of chiral indanes by means of enantioselective catalysis, with major progress being achieved in organocatalysis and C–H activation chemistry.

Non-stabilized enolates – versatile nucleophiles in transition metal-catalysed allylic alkylations

This review covers new developments in the transition metal-catalyzed allylic alkylations of non-stabilized enolates, preferentially generated from ketone, esters or amides.

Preparation of amino-substituted indenes and 1,4-dihydronaphthalenes using a one-pot multireaction approach: total synthesis of oxybenzo[c]phenanthridine alkaloids

Allylic trichloroacetimidates bearing a 2-vinyl or 2-allylaryl group have been designed as substrates for a one-pot, two-step multi-bond-forming process leading to the general preparation of aminoindenes and amino-substituted 1,4-dihydronaphthalenes. The synthetic utility of the privileged structures formed from this one-pot process was demonstrated with the total synthesis of four oxybenzo[c]phenanthridine alkaloids, oxychelerythrine, oxysanguinarine, oxynitidine, and oxyavicine. An intramolecular biaryl Heck coupling reaction, catalyzed using the Hermann-Beller palladacycle was used to effect the key step during the synthesis of the natural products.

Ferrocene phosphane-heteroatom/carbon bidentate ligands in asymmetric catalysis

A review of chiral ferrocene ligands featuring a combination of phosphorus and other elements as donor atoms in the asymmetric catalysis.