Recent Advances in Transition-Metal-Free (4+3)-Annulations

Lam, Heather; Abel-Snape, Xavier; Köllen, Martin F. and Lautens, Mark (2021): Recent Advances in Transition-Metal-Free (4+3)-Annulations. In: Synthesis-Stuttgart, Vol. 53, No. 22: pp. 4134-4177

Abstract

(4+3)-Annulations are incredibly versatile reactions which combine a 4-atom synthon and a 3-atom synthon to form both 7-membered carbocycles as well as heterocycles. We have previously reviewed transition-metal-catalyzed (4+3)-annulations. In this review, we will cover examples involving bases, NHCs, phosphines, Lewis and Bronsted acids as well as some rare examples of boronic acid catalysis and photocatalysis. In analogy to our previous review, we exclude annulations involving cyclic dienes like furan, pyrrole, cyclohexadiene or cyclopentadiene, as Chiu, Harmata, Fernandes and others have recently published reviews encompassing such substrates. We will however discuss the recent additions (2010-2020) to the literature on (4+3)-annulations involving other types of 4-atom-synthons. 1 Introduction 2 Bases 3 Annulations Using N-Heterocyclic Carbenes 3.1 N-Heterocyclic Carbenes (NHCs) 3.2 N-Heterocyclic Carbenes and Base Dual-Activation 4 Phosphines 5 Acids 5.1 Lewis Acids 5.2 Bronsted Acids 6 Boronic Acid Catalysis and Photocatalysis 7 Conclusion

• Item Type: Journal article
• Faculties: Chemistry and Pharmacy > Department of Chemistry
• Subjects: 500 Science > 540 Chemistry
• ISSN: 0039-7881
• Language: English