C–C Bond Cleavages of Cyclopropenes: Operating for Selective Ring-Opening Reactions

Abstract

This review highlights key reactivities relying on C–C bond cleavages of cyclopropenes. Metal-catalyzed and metal-free transformations are covered in reactions involving direct ring-opening processes or transformations through nonisolable cyclopropane intermediates generated from cyclopropenes. Special emphasis is on the synthetic utility and mechanistic aspects of methodologies discussed along the revision. Different types of reactivities are covered in separate sections including generation of vinyl carbenes and their reactions, metathesis processes, heterocycles syntheses, SEAr reactions, metalation-ring opening sequences, cycloadditions involving ring-cleavages or rearrangements. The focus is on results described from 2007 to the end of 2019, yet relevant pioneering transformations are eventually included.

Copper-catalyzed [3 + 1] cyclization of cyclopropenes/diazo compounds and bromodifluoroacetamides: facile synthesis of α,α-difluoro-β-lactam derivatives

“…Given that cyclopropenes can usually serve as carbene precusors 12 and considering our recent work on the copper-catalyzed ring-opening coupling reaction of cyclopropene and phosphite via a possible copper vinyl carbene species, 13 we chose cyclopropene ( 2a ) for the initial test of the [3 + 1] cyclization. The reaction of α-bromodifluoroacetamide 1a (0.2 mmol) and 2a (0.24 mmol, 1.2 equiv.)…”

Recent Advances on Synthetic Methodology Merging C–H Functionalization and C–C Cleavage

“…As mentioned in the introductory section of this review, the release of the strain of carbocyclic structures is one of the driving forces that can promote the cleavage of C–C bonds [ 26 ], generating intermediates of different nature depending on the experimental conditions which can further evolve intra- or intermolecularly to afford new organic scaffolds. This section presents recent progress carried out on the different approaches where the functionalization of a C–H bond is achieved through the use of cyclopropyl and cyclobutyl scaffolds [ 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ].…”

Transition-Metal-Catalyzed Polymerization of Cyclopropenes

“…They show high reactivity moreover the diverse reaction patterns, owing to the ring strain ( ≈ 226 kJ/mol). [7][8][9] The CPEs can undergo several reactions when catalyzed by the transition-metals, [10] including the metal carbene-resulted reactions, [11][12][13][14] C-C double bond functionalization [15][16] and cycloadditions. [17][18] These reaction patterns of the CPEs are useful showing of the tool-box means expanded in the organic synthetic chemistry.…”