Catalytic asymmetric synthesis of α-stereogenic carboxylic acids: recent advances

Chiral carboxylic acids bearing an α-stereogenic center constitute the backbone of many natural products and therapeutic reagents as well as privileged chiral ligands and catalysts. Hence, it is not surprising that a large number of elegant catalytic asymmetric strategies have been developed toward the efficient synthesis of α-chiral carboxylic acids, such as α-hydroxy acids and α-amino acids. In this review, the recent advances in asymmetric synthesis of α-stereogenic free carboxylic acids via organocatalysis and transition metal catalysis are summarized (mainly from 2010 to 2020). The content is organized by the reaction type of the carboxyl source involved, including asymmetric functionalization of substituted carboxylic acids, cyclic anhydrides, α-keto acids, substituted α,β-unsaturated acids and so on. We hope that this review will motivate further interest in catalytic asymmetric synthesis of chiral α-substituted carboxylic acids.

Bifunctional amino sulfonamide-catalyzed asymmetric conjugate addition to alkenyl alkynyl ketimines as enone surrogates

A bifunctional amino sulfonamide-catalyzed asymmetric conjugate addition of aldehydes to alkenyl alkynyl ketimines as reactive surrogates for enones has been developed. Use of a phenylcyclopropane-based amino sulfonamide catalyst, which can activate and orient the ketimines through hydrogen bonding, affords the desired conjugate adducts with high chemo-, diastereo- and enantioselectivity.

The oxa-Michael reaction in the synthesis of 5- and 6-membered oxygen-containing heterocycles

In this review, we provide an updated account on the recent advances and applications of oxa-Michael reaction in the synthesis 5- and 6-membered monocyclic oxygen-containing heterocyclic compounds published in the literature since 2013 to date.

Merging singlet-oxygen induced furan oxidations with organocatalysis: synthesis of enantiopure cyclopentanones and hydrindanes

A general, flexible and highly effective method for the regio-, diastereo- & enantioselective one-pot synthesis of important carbocycles, namely, enantiopure cyclopentanones and their hydrindane congeners is presented.

A dienamine-mediated deconjugative addition/cyclization cascade of γ,γ-disubstituted enals with carboxylic acid-activated enones: a rapid access to highly functionalized γ-lactones

An aminocatalytic deconjugative addition/cyclization cascade of γ,γ-disubstituted enals with carboxylic acid-activated enones was realized, giving rise to highly functionalized γ-lactones with excellent enantioselectivities.

Asymmetric Multifunctional Modular Organocatalysis: One-Pot Direct Strategy to Enantiopure α,β-Disubstituted γ-Butyrolactones

A simple and efficient approach to enantioenriched α,β-disubstituted γ-butyrolactones has been developed through multifunctional modular organocatalysis in a highly enantioselective (>99% ee) and diastereoselective (>30:1) manner following a one-pot sequential Michael-hemiacetalization-oxidation reaction. The catalytic process has great substrate compatibility, and the products have been transformed to synthetically useful molecules. The methodology has also been applied to the formal synthesis of (+)-Pilocarpine.

Desymmetrizing Hydroformylation of Dihydromuconic Acid Diesters: Application to the Synthesis of (±)-Vindeburnol

The desymmetrizing hydroformylation of internal alkenes derived from dihydromuconic acid is described. The study of this reaction afforded easy access to polyfunction aldehydes. After the evaluation of the reactivity of the dimethyl ester derivative with various primary amines, this methodology was used to design a rapid synthesis of (±)-vindeburnol from tryptamine in only two steps.

Enantio- and diastereoselective synthesis of tetrahydrofuro[2,3-b]furan-2(3H)-one derivatives and related oxygen heterocycles via an asymmetric organocatalytic cascade process

Tetrahydrofuro[2,3-b]furan-2(3H)-one derivatives were formed via a novel asymmetric organocatalytic cascade process with excellent stereoselectivity in one single operation.

An efficient lactamisation/N-acyliminium Pictet–Spengler domino strategy for the diasteroselective synthesis of polyhydroxylated quinoxalinone, β-carboline and quinazolinone derivatives

A novel Pictet–Spengler cascade sequence has been developed. It involves a lactamisation/N-acyliminium key step and gives a diverse set of sugar-derived fused polycyclic heterocycles diastereoselectively and efficiently.