Synlett 2020; 31(02): 117-124
DOI: 10.1055/s-0039-1690753
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© Georg Thieme Verlag Stuttgart · New York

Lewis Base Catalysis Based on Homoconjugate Addition: Rearrangement of Electron-Deficient Cyclopropanes and Their Derivatives

Kaki Raveendra Babu
,
Xin He
,
Silong Xu
We are grateful for financial support from the National Natural Science Foundation of China (Nos. 21871218 and 21602167), the Natural Science Basic Research Plan in Shaanxi Province of China (2016JQ2019), the China Postdoctoral Science Foundation (Nos. 2014M550484, 2015T81013, and 2015M580830), Shaanxi Province Postdoctoral Science Foundation, and the Key Laboratory Construction Program of Xi’an Municipal Bureau of Science and Technology (201805056ZD7CG40).
Further Information

Publication History

Received: 11 October 2019

Accepted after revision: 06 November 2019

Publication Date:
20 November 2019 (online)


Abstract

Cyclopropane is one of the most reactive functionalities owing to its intrinsic ring strain. Transition-metal catalysis and Lewis acid catalysis have been extensively used in ring openings of cyclopropanes; however, Lewis base-catalyzed activation of cyclopropanes remains largely unexplored. Upon nucleophilic attack with Lewis bases, cyclopropanes undergo ring cleavage in a manner known as homoconjugate addition to form zwitterionic intermediates, which have significant potential for reaction development but have garnered little attention. Here, we present a brief overview of this area, with an emphasis on our recent efforts on Lewis base-catalyzed rearrangement reactions of electron-deficient cyclopropanes using the homoconjugate addition process.

1 Introduction

2 DABCO-Catalyzed Cloke–Wilson Rearrangement of Cyclopropyl Ketones

3 Hydroxylamine-Mediated Tandem Cloke–Wilson/Boulton–­Katritzky Reaction of Cyclopropyl Ketones

4 Phosphine-Catalyzed Rearrangement of Vinylcyclopropyl Ketones To Form Cycloheptenones

5 Phosphine-Catalyzed Rearrangement of Alkylidenecyclopropyl Ketones To Form Polysubstituted Furans and Dienones

6 Conclusion and Outlook