Cooperative Catalysis for the Highly Diastereo- and Enantioselective [4+3]-Cycloannulation of ortho-Quinone Methides and Carbonyl Ylides

Enantioselective Cyclopropanation/[1,5]-Hydrogen Shift to Access Rauhut-Currier Product

A Michael addition initiated cyclopropanation/[1,5]-hydrogen shift has been developed for the enantioselective synthesis of Rauhut-Currier products. The reaction of α-alkyl diazoesters and in situ generated o-quinone methides proceeds in the presence of chiral oxazaborolidinium ion, providing Z-stereocontrolled Rauhut-Currier products in high yields (up to 96%) with excellent Z/E selectivities (>20:1) and enantioselectivities (up to >99% ee). The synthetic utility was illustrated by conversion of the product to 3,4-dihydrocoumarins with two adjacent chiral stereocenters.

Auto-tandem palladium/phosphine cooperative catalysis: synthesis of bicyclo[3.1.0]hexenes by selective activation of Morita–Baylis–Hillman carbonates

A new palladium/phosphine cooperatively catalytic sequential annulation strategy has been developed for the synthesis of bicyclo[3.1.0]hexene derivatives.

Hydroquinine-catalyzed asymmetric 1,4-hydrophosphination of in situ generated aza-o-quinone methides with H-phosphine oxides

An organocatalytic enantioselective 1,4-addition of H-phosphine oxides to in situ generated aza-o-quinone methides has been successfully established using hydroquinine.

Rhodium-Catalyzed Diastereoselective [3 + 2] Cycloaddition of Carbonyl Ylide: An Access to the Core Ring System of Cordigol and Lophirone H

This paper describes a new synthetic strategy for the construction of tricyclic chromeno/quinolino furan frameworks via creation of two new rings and three contiguous stereogenic centers with high diastereoselectivity through a rhodium-catalyzed intramolecular carbonyl ylide cycloaddition reaction for the first time. This protocol allows the synthesis of the core ring system of natural products such as cordigol and lophirone H.

Regio- and Diastereoselective Dimerization of Diazo Carbonyls: A Cooperative Catalytic Approach to Complex Scaffolds with Four Contiguous Stereocenters

Starting from readily available o-diazoacyl-substituted arene carboxylates, scaffolds with the 5,9-epoxycyclohepta[b]pyran-2(3H)-one core were obtained by cooperative RhII , Lewis and Brønsted acid catalysis. Four new bonds, three functional groups (lactone, ketal, and alcohol) and four contiguous stereocenters are formed during this regio- and diastereoselective process in a single synthetic step. Intensive optimization and mechanistic studies, including the trapping, isolation, and elucidation of reaction intermediates, led to a plausible mechanistic scenario. The reaction is proposed to involve carbonyl ylides but also transient species of the ketocarbene equilibrium that undergo a cascade of cycloaddition and skeletal rearrangements.

Recent Advances in Transition-Metal-Catalyzed (4+3)-Cycloadditions

A (4+3)-cycloaddition combines a four-atom synthon and three-atom synthon to form seven-membered rings. In the past decade, many improvements have been made to this class of cycloaddition, including excellent diastereo- and enantioselectivities, both intra- and intermolecularly. Through the strategic use of transition-metal catalysts, acids, bases, and organocatalysts, it is possible to perform the cycloaddition on a variety of substrates, generating novel seven-membered rings. With these advances, (4+3)-cycloaddition has also been applied to the synthesis of biologically relevant compounds and natural products. We exclude the cycloadditions of cyclic dienes such as furan, pyrrole, cyclohexadiene or cyclopentadiene as Chiu, Harmata, Mascareñas­ and others have recently published thorough reviews on that topic. We will however discuss the recent additions (2009–2020) to the literature for the (4+3)-cycloadditions involving other types of four-atom synthons.

1 Introduction

2 Rhodium

2.1 Cyclopropanation/Cope Rearrangement

2.2 C–H activation

3 Gold, Silver

4 Copper

5 Palladium, Platinum, Iridium

6 Dual-Activation

7 Conclusion

Cooperative Catalysis for the Highly Diastereo- and Enantioselective [4+3]-Cycloannulation of ortho-Quinone Methides and Carbonyl Ylides

We describe herein a highly diastereo- and enantioselective [4+3]-cycloannulation of ortho-quinone methides and carbonyl ylides to furnish functionalized oxa-bridged dibenzooxacines with excellent yields and stereoselectivity in a single synthetic step. The combination of rhodium and chiral phosphoric acid catalysis working in concert to generate both transient intermediates in situ provides direct access to complex bicyclic products with two quaternary and one tertiary stereogenic centers. The products may be further functionalized into valuable and enantiomerically highly enriched building blocks.

Construction of chiral chroman scaffolds via catalytic asymmetric (4 + 2) cyclizations of para-quinone methide derivatives with 3-vinylindoles

The title reaction has been established in the presence of chiral phosphoric acid, affording chiral chroman derivatives bearing an indole moiety in high yields and with moderate to good stereoselectivities.

Organocatalytic and enantioselective [4+2] cyclization between hydroxymaleimides and ortho-hydroxyphenyl para-quinone methide-selective preparation of chiral hemiketals

A highly effective and enantioselective organocatalytic [4+2] cyclization has been disclosed, and a series of new chiral hemiketals containing chromane and succinimide frameworks have been firstly prepared in excellent results with 100% atom efficacy.

Divergent syntheses of spirooxindoles from oxindole-embedded four-membered synthon via cycloaddition reactions

The construction of five and six membered heterocycle fused spirooxindoles was achieved via the [4 + 1] and formal [4 + 2] cycloadditions between our rationally designed four-membered synthons and pyridinium methylides and α-bromoacetophenones, respectively.