Highly Enantioselective and Anti-Diastereoselective Catalytic Intermolecular Glyoxylate–Ene Reactions: Effect of the Geometrical Isomers of Alkenes

Cyclocarbonylation of Allenyl Glyoxylate Strategy to Build the Tricyclic Core of Cyclocalopin A

An approach for the construction of the tricyclic framework of naturally occurring cyclocalopin A is described. The establishment of the crucial intermediate α-methylene bis-γ,δ-lactone involves a [2 + 2 + 1]-cyclocarbonylation of newly introduced allenyl glyoxylate via direct methods using Mo(CO)₆ or sequential reaction pathways. The sequential reaction route involved a stannylative cyclization by Pd(0) catalyst, bromination of an vinyl stannane moiety, and final cyclocarbonylation by palladium catalysis to provide the bis-γ,δ-lactone. The feasibility of forming the spiro-system by an exo-selective [4 + 2]-cycloaddition was accomplished.

Enantioselective Indium-Catalyzed Transformations

This review updates the field of enantioselective indium-catalyzed transformations of all types since 2012. It shows that asymmetric indium catalysis, that suits the growing demand for greener processes, offers a real opportunity to replace toxic metals in the near future.

1 Introduction

2 Allylations, Propargylations, and Allenylations of Carbonyl Compounds and Derivatives

2.1 Allylations

2.2 Propargylations and Allenylations

3 Cycloadditions

3.1 Hetero-Diels–Alder Cycloadditions

3.2 1,3-Dipolar Cycloadditions

4 Miscellaneous Reactions

5 Domino and Tandem Reactions

6 Conclusion

Cationic aluminum, gallium, and indium complexes in catalysis

The introduction of cationic charge allows cationic group 13 complexes to be excellent Lewis acid catalysts. Cationic aluminum, gallium, and indium complexes in catalysis are comprehensively reviewed based on the reaction type.

Chiral strong Brønsted acid-catalyzed enantioselective addition reaction of simple olefins with ethyl glyoxylate

An enantioselective intermolecular addition reaction of 1,1,2-trisubstituted and 1,2- disubstituted simple olefins with ethyl glyoxylate was developed using F₁₀BINOL-derived N-sulfonyl phosphoramide as a chiral strong Brønsted acid catalyst.

F10BINOL-derived chiral phosphoric acid-catalyzed enantioselective carbonyl-ene reaction: theoretical elucidation of stereochemical outcomes

An enantioselective carbonyl-ene reaction of 1,1-disubstituted olefins with ethyl glyoxylate was accomplished using an F₁₀BINOL-derived chiral phosphoric acid of which the perfluoro-binaphthyl skeleton is beneficial not only for adopting high catalytic activity but also for creating an effective chiral environment.

An F₁₀BINOL-derived chiral phosphoric acid was shown to be an effective catalyst for an enantioselective carbonyl-ene reaction of 1,1-disubstituted olefins with ethyl glyoxylate as the common enophile. The perfluoro-binaphthyl skeleton is beneficial not only for adopting high catalytic activity but also for creating an effective chiral environment for enantioselective transformations. Indeed, the reaction afforded enantio-enriched homoallylic alcohols in high yields with high enantioselectivities. Theoretical studies identified that the multi-point C–H···O hydrogen bonds and the π interactions between the substrates and the 6-methoxy-2-naphthyl substituents at the 3,3′-positions of the F₁₀BINOL skeleton play a crucial role in determining the stereochemical outcomes. The significance of the perfluoro-binaphthyl skeleton in achieving the high enantioselectivity was also evaluated through a structural analysis of the catalysts.

Direct Synthesis of a Dioxabenzobicyclo[3.2.1]octane Core from Salicylaldehydes

A copper(II) trifluoromethanesulfonate via Prins reaction between salicylaldehydes and allyl alcohols is realized under mild conditions. A series of compounds containing dioxabenzobicyclo[3.2.1]octane motifs are obtained in moderate to good yields. The current method can efficiently construct the valuable structural motif from easily accessed starting materials, providing a smooth method to build benzobicyclo skeletons.

Enantioselective indium(i)-catalyzed [4 + 2] annulation of alkoxyallenes and β,γ-unsaturated α-keto esters

An indium(i)–chiral phosphoric acid complex was found to catalyze the enantioselective [4 + 2] annulation reaction of β,γ-unsaturated α-keto esters with alkoxyallenes, affording cyclic O,O-acetals in good yields and with high regio- and stereo-selectivities.

Zn/Sc bimetallic relay catalysis: one pot cycloisomerization/carbonyl–ene reaction toward oxazole derivatives

A novel tandem metal relay catalytic system combining Zn(ii)-catalyzed cycloisomerization and a Sc(iii)-catalyzed carbonyl–ene reaction has been successfully developed.