Recent Advances in the Chemistry of Doubly Activated Cyclopropanes: Synthesis and Reactivity

Abstract

Diactivated cyclopropanes containing two geminal electron withdrawing groups, commonly called as ‘Doubly Activated Cyclopropanes’ are useful synthons for the synthesis of many interesting natural products and functionalized molecules. These geminal electron withdrawing groups (EWG’s) facilitate the regioselective ring opening of cyclopropanes by polarizing the C-C bond adjacent to it. This polarization also allows them to undergo 1,3 dipolar cycloaddition reactions when substituted with a suitable electron donor substituent at the adjacent carbon (donor-acceptor cyclopropanes) in the presence of suitable dipolarophiles. In this review, we discuss the recent advances in the chemistry of doubly activated cyclopropanes: their synthesis, reactions and applications in total synthesis.

Asymmetric cascades of the π-allyl complex: a journey from transition-metal catalysis to metallaphotocatalysis

“…The different reactive sides of these scaffolds have been visited well in different chemical environments and enormous methods are being documented in the literature. [58][59][60][61] Given the efficiency of these moieties towards the generation of 1,3-dipole, they are also being used to generate p-allyl intermediates under transition metal catalysis.…”

Synthesis of 1-aryl-2,3-diaroyl cyclopropanes from 1,3,5-triaryl-1,5-diketones and their transformation into E,E-1,4-diaryl-1,3-butadienes

“…Both methods have been extensively used for the access of various types of donor–acceptor cyclopropanes in both racemic and chiral forms. 5…”

Phosphine-Promoted Ring Opening/Recyclization of Cyclopropyl Ketones to Access Hydrofluorenones

“…The ring-opening and recyclization reactions of donor–acceptor cyclopropanes (DACs, A ) and vinylcyclopropanes (VCPs, B ) are well-established compared to monoactivated cyclopropanes ( C ) and cyclopropanes with two geminal activators ( D ) (Scheme ). The ring transformations of activated cyclopropanes under acidic conditions or transition metal catalysis have been extensively investigated …”

“…However, the expected products (such as O or Q ) were not observed. At this stage, we came across the seminal works of Hanafusa, Danishefsky, and others, where the role of geminal activating groups on cyclopropanes was demonstrated as a solution to their ring-opening transformations. Taking inspiration from these studies, we modified the substrate to the gem -diactivated cyclopropane 1c and subjected it to various conditions, and the results are compiled in Table .…”