Synthesis 2020; 52(01): 27-39
DOI: 10.1055/s-0039-1690695
short review
© Georg Thieme Verlag Stuttgart · New York

The Bonding and Reactivity of α-Carbonyl Cyclopropanes

Alexander J. Craig
,
Department of Chemistry, University of Otago, Dunedin, New Zealand   Email: alexcraig93@hotmail.co.nz   Email: bhawkins@chemistry.otago.ac.nz
› Author Affiliations
We thank the University of Otago and the Department of Chemistry for financial support.
Further Information

Publication History

Received: 19 July 2019

Accepted after revision: 12 September 2019

Publication Date:
01 October 2019 (online)


Abstract

The cyclopropane functionality has been exploited in a myriad of settings that range from total synthesis and methodological chemistry, to medical and materials science. While it has been seen in such a breadth of settings, the typical view of the cyclopropane moiety is that its reactivity is derived primarily from the release of ring strain. While this simplified view is a useful shorthand, it ignores the specific nature of cyclopropyl molecular orbitals. This review aims to present the different facets of cyclopropane bonding by examining the main models that have been used to explain the reactivity of the functionality over the years. However, even with advanced theory, being able to precisely predict the reactivity of an exact system is nigh impossible. Specifically chosen, carbonyl-bearing cyclopropyl species act as so-called acceptor cyclopropanes and, if correctly derivatised, donor–acceptor cyclopropanes. By undertaking a case study of the history of carbonyl cyclopropanes in organic synthesis, this review highlights the relationship between the understanding of theory and pattern recognition in developing new synthetic methods and showcases those successful in balancing this critical junction.

1 Cyclopropanes

2 The Strain Model

3 The Forster–Coulsin–Moffit Model

4 The Walsh Model

5 Acceptor, Donor, and Donor–Acceptor Cyclopropanes

6 Reactions of Carbonyl Cyclopropanes