Synthesis 2020; 52(17): 2427-2449
DOI: 10.1055/s-0039-1690875
review
© Georg Thieme Verlag Stuttgart · New York

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

,
Mark Lautens
Davenport Research Laboratories, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada   Email: mark.lautens@utoronto.ca
› Author Affiliations
The authors would like to thank the Natural Sciences and Engineering Research Council (NSERC), Alphora Inc., and the University of Toronto for funding. H. Lam thanks NSERC for a PGSD.
Further Information

Publication History

Received: 25 January 2020

Accepted after revision: 10 March 2020

Publication Date:
02 April 2020 (online)


Dedicated to the 50th anniversary of SYNTHESIS

Abstract

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