Au(I)/(R)-BINOL-Ti(IV) Concerted Catalyzed Asymmetric Cascade Cycloaddition Reaction of Arylalkynols

Dual Photoredox- and Titanium Catalysis-Enabled Three-Component Radical Propargylation of Aldehydes with 1,3-Enynes

Herein, a straightforward and practical strategy involving radicals for the three-component carbonyl propargylation via dual photoredox and titanium catalysis is presented. This strategy delivers homopropargyl alcohols and includes readily available starting materials, a broad substrate scope, high functional group tolerance, and mild reaction conditions. Catalytic Cp2TiCl2, recognized as an inexpensive, nontoxic, and bench-stable titanium source, is employed.

Sc(OTf)3-Catalyzed Precise Construction of Medium-Sized [4.2.1]-Oxabridged Scaffolds

In this study, the readily available and inexpensive Sc(OTf)3 was utilized to activate ortho-benzoyl diazo compounds to in situ generate highly reactive cyclic 1,3-dipoles, which underwent a regioselective [4 + 3] cycloaddition with dioxopyrrolidines, yielding the [4.2.1]-oxabridged scaffolds bearing multiple contiguous quaternary carbon centers with high diastereoselectivities. The method not only exhibited significant economic and operational advantages but also demonstrated practical value through gram-scale synthesis and derivatization experiments.

ortho-Alkynyl Benzyl Alcohols as C6 Synthons in Regioselective Construction of Polysubstituted Naphthalenes

A straightforward methodology for the assembly of polysubstituted naphthalenes from ortho-alkynyl benzyl alcohols, enabled by using catalytic amounts of Tf2O, has been developed. This transformation not only features transition-metal free and without using other bases and additives but also provides a new synthetic application for ortho-alkynyl benzyl alcohols, i.e., as C6 synthons for the construction of PAHs.

Gold-based enantioselective bimetallic catalysis

Multimetallic catalysis is a powerful strategy to access complex molecular scaffolds efficiently from easily available starting materials. Numerous reports in the literature have demonstrated the effectiveness of this approach, particularly for capitalizing on enantioselective transformations. Interestingly, gold joined the race of transition metals very late making its use in multimetallic catalysis unthinkable. Recent literature revealed that there is an urgent need to develop gold-based multicatalytic systems based on the combination of gold with other metals for enabling enantioselective transformations that are not possible to capitalize with the use of a single catalyst alone. This review article highlights the progress made in the field of enantioselective gold-based bimetallic catalysis highlighting the power of multicatalysis for accessing new reactivities and selectivities which are beyond the reach of individual catalysts.

exo'-Selective Construction of Spirobipyrrolidines by the Silver-catalyzed Asymmetric [3+2] Cycloaddition of Imino Esters with 4-Benzylidene-2,3-dioxopyrrolidines

The unprecedented Ag-catalyzed exo ' -selective [3+2] cycloaddition of imino esters with 4-benzylidene-2,3-dioxopyrrolidines is described. The reaction was efficiently catalyzed by AgOAc/( R , S p )-ThioClickFerrophos (TCF) leading to the construction of the corresponding spirobipyrrolidine scaffolds in excellent enantio- and diastereoselectivities. This reaction is the first example of a silver-catalyzed exo ' -selective asymmetric [3+2] cycloaddition, as well as the first exo ' -selective spirobipyrrolidine construction via a [3+2] cycloaddition process using imino esters. The wide substrate scope of this reaction enabled the preparation of structurally diverse spirobipyrrolidine derivatives, which are attracting attention as targets for drug discovery. Mechanistic studies suggested that the unusual exo ' -selectivity of this reaction is not due to epimerization following the common exo - or endo -selective cycloaddition, but instead is due to a stepwise Michael addition/Mannich sequence with bond rotation.