Highly Efficient Asymmetric Mannich Reaction of Dialkyl α-Diazomethylphosphonates with N-Carbamoyl Imines Catalyzed by Chiral Brønsted Acids

Chiral Phosphoric Acid Catalyzed Asymmetric Mannich Reaction of 2-Aryl-3H-indol-3-ones with α-H Diazoacetates

An asymmetric Mannich reaction between 2-aryl-3H-indol-3-ones and α-H diazoacetates catalyzed by chiral phosphoric acid was developed. This strategy achieves the effective synthesis of chiral 2,2-disubstituted indolin-3-ones bearing a quaternary stereocenter and containing a diazo group in the C2 substituent (up to >99% ee and 82% yield). To demonstrate the importance of the synthesized 2,2-disubstituted indolin-3-ones and the diversity of their diazo group reactions, we successfully achieved the relevant transformation reactions with a diazo group (such as hydroxylation, hydrogenation, intramolecular cyclization, etc.) in the C2 substituent.

Controlling Stereoselectivity with Noncovalent Interactions in Chiral Phosphoric Acid Organocatalysis

Chiral phosphoric acids (CPAs) have emerged as highly effective Brønsted acid catalysts in an expanding range of asymmetric transformations, often through novel multifunctional substrate activation modes. Versatile and broadly appealing, these catalysts benefit from modular and tunable structures, and compatibility with additives. Given the unique types of noncovalent interactions (NCIs) that can be established between CPAs and various reactants─such as hydrogen bonding, aromatic interactions, and van der Waals forces─it is unsurprising that these catalyst systems have become a promising approach for accessing diverse chiral product outcomes. This review aims to provide an in-depth exploration of the mechanisms by which CPAs impart stereoselectivity, positioning NCIs as the central feature that connects a broad spectrum of catalytic reactions. Spanning literature from 2004 to 2024, it covers nucleophilic additions, radical transformations, and atroposelective bond formations, highlighting the applicability of CPA organocatalysis. Special emphasis is placed on the structural and mechanistic features that govern CPA-substrate interactions, as well as the tools and techniques developed to enhance our understanding of their catalytic behavior. In addition to emphasizing mechanistic details and stereocontrolling elements in individual reactions, we have carefully structured this review to provide a natural progression from these specifics to a broader, class-level perspective. Overall, these findings underscore the critical role of NCIs in CPA catalysis and their significant contributions to advancing asymmetric synthesis.

An overview of the applications of chiral phosphoric acid organocatalysts in enantioselective additions to CO and CN bonds

Since 2004, chiral phosphoric acids (CPAs) have emerged as highyl efficient organocatalysts, providing excellent results in a wide reaction scope. In this review, the applications of CPA for enantioselective additions to CO and CN bonds are covered.

Asymmetric acyl-Mannich reaction of isoquinolines with α-(diazomethyl)phosphonate and diazoacetate catalyzed by chiral Brønsted acids

α-Diazo-β-isoquinoline derivatives were obtained in excellent yields and enantioselectivities by asymmetric acyl-Mannich reaction of (diazomethyl)phosphonate or diazoacetate with isoquinolines.

Chemodivergent and Stereoselective Construction of gem-Difluoroallylic Amines from Masked Difluorodiazo Reagents

We report a general and efficient approach to construct achiral and chiral gem-difluoroallylic amines from a masked difluorodiazo reagent (PhSO₂CF₂CHN₂) and readily available imines. This facile protocol takes advantage of the phenylsulfonyl and diazo moieties as efficient activating and directing groups to assist difluoroalkyl incorporation and facilitate the chemodivergent and stereoselective formation of gem-difluoroallylic amines.

BINOPtimal: a web tool for optimal chiral phosphoric acid catalyst selection

A catalyst selection program, BINOPtimal, has been developed.

Switchable Synthesis of 3-Substituted 1H-Indazoles and 3,3-Disubstituted 3H-Indazole-3-phosphonates Tuned by Phosphoryl Groups

3-Alkyl/aryl-1H-indazoles and 3-alkyl/aryl-3H-indazole-3-phosphonates were synthesized efficiently through a 1,3-dipolar cycloaddition reaction between α-substituted α-diazomethylphosphonates and arynes under simple reaction conditions. The product distribution was controlled by the phosphoryl group, which acted both as a tuning group and a traceless group in the reaction.

A chiral Brønsted acid-catalyzed highly enantioselective Mannich-type reaction of α-diazo esters with in situ generated N-acyl ketimines

A chiral phosphoric acid-catalyzed asymmetric Mannich-type reaction of α-diazo esters with in situ generated N-acyl ketimines, derived from 3-aryl-3-hydroxyisoindolinones has been demonstrated. The reaction proceeds smoothly under mild reaction conditions.

Selecting Chiral BINOL-Derived Phosphoric Acid Catalysts: General Model To Identify Steric Features Essential for Enantioselectivity

Choosing the optimal catalyst for a new transformation is challenging because the ideal molecular requirements of the catalyst for one reaction do not always simply translate to another. Large groups at the 3,3' positions of the binaphthol rings are important for efficient stereoinduction but if they are too large this can lead to unusual or poor results. By applying a quantitative steric assessment of the substituents at the 3,3' positions of the binaphthol ring, we have systematically studied the effect of modulating this group on enantioselectivity for a wide range of reactions involving imines, and verified this analysis using ONIOM calculations. We have shown that in most reactions, the stereochemical outcome depends on both proximal and remote sterics. Summarising detailed calculations into a simple qualitative model identifies and explains the steric features required for high selectivity. This model is consistent with seventy seven papers reporting reactions (over 1000 transformations in total), and provides a straightforward decision tree for selecting the best catalyst.

Enantioselective Hydrophosphonylation of in Situ Generated N-Acyl Ketimines Catalyzed by BINOL-Derived Phosphoric Acid

An efficient route to pharmacologically interesting isoindolinone-based α-amino phosphonates is described via asymmetric hydrophosphonylation of in situ generated ketimines catalyzed by BINOL-derived phosphoric acid. The reaction proceeds smoothly at ambient temperature affording a variety of α-amino phosphonates with a quaternary stereogenic center embedded in isoindolinone motif in high yields with excellent enantiomeric ratios (up to 98.5:1.5 er). Several interesting transformations of the products into valuable synthetic intermediates are also depicted.

Palladium-catalyzed asymmetric allylic amination: enantioselective synthesis of chiral α-methylene substituted β-aminophosphonates

Palladium catalyzed asymmetric allylic amination of 2-diethylphosphonate-substituted allylic acetates in the presence of SKP ligands afforded the corresponding chiral β-aminophosphonates in good yields, high regioselectivities, and excellent enantioselectivities.

Silver-catalyzed nucleophilic substitution of aminals with ethyl diazoacetate: a new pathway to β-amino-α-diazoesters

A novel silver-catalyzed nucleophilic substitution of aminals with ethyl diazoacetate producing β-amino-α-diazoesters has been developed. A series of aminals with different amino moieties and substituents were successfully incorporated in this reaction.

A new reactivity mode for the diazo group: diastereoselective 1,3-aminoalkylation reaction of β-amino-α-diazoesters to give triazolines

A novel mode of reactivity for the diazo group, the 1,3-addition of a nucleophile and an electrophile to the diazo group, has been realized in the intramolecular aminoalkylation of β-amino-α-diazoesters to form tetrasubstituted 1,2,3-triazolines. The reaction exhibited a broad scope, good functional group tolerance, and excellent diastereoselectivity. In addition, a new Au-catalyzed intramolecular transannulation reaction of the obtained propargyl triazolines to give pyrroles has been discovered.

Regiospecific and highly stereoselective synthesis of β-amino (Z)-enylphosphonates via β-hydrogen migration reaction of dialkyl α-diazophosphonates catalyzed by AgOTf

The diazo decomposition of dialkyl α-diazophosphonates in the presence of AgOTf provides an efficient one-step route to a variety of β-amino (Z)-enylphosphonates in good yields with complete control over regio- and stereochemistry.

Pyridine group assisted addition of diazo-compounds to imines in the 3-CC reaction of 2-aminopyridines, aldehydes, and diazo-compounds

A novel three-component coupling (3-CC) reaction of 2-aminoazines, aromatic aldehydes, and diazo-compounds producing polyfunctional β-amino-α-diazo-compounds has been developed. The reaction features an unprecedented heterocycle-assisted addition of a diazo-compound to an imine. The obtained diazoesters were efficiently converted into valuable heterocycles as well as β-amino acid derivatives.