Cyclopropenylium Cations, Cyclopropenones, and HeteroanaloguesRecent Advances

Cyclopropenylidenes: From Interstellar Space to an Isolated Derivative in the Laboratory

“…Author manuscript; available in PMC 2008 June 13. the corresponding cyclopropenium salts (4) (14), bis(dialkylamino)cyclopropenylidenes such as 1c have been among the most frequently targeted derivatives (15)(16)(17). The transient existence of 1c has been postulated based on chemical trapping experiments, but it has been described as a highly unstable molecule, defying isolation or even observation in the free state (15)(16)(17)(18)(19)(20)(21).…”

“…Moreover, for cyclopropenylidenes, the conjugate acids, namely the cyclopropenium salts (4) (Fig. 1), are available in large quantities, thermally very stable, and easy to handle (14). The bis(diisopropylamino) derivative 4c is even insensitive to water (34).…”

Synthesis, Electrochemistry and Antitumor Activity of 1’H, 3’H(Me)-spiro-[(aza)benzimidazoline-2’, 3-(1,2-diferrocenylcyclopropenes)], 2-(1,2-Diferrocenylvinyl)benz- and Azabenzimidazoles

“…Diaryl-and diferrocenylcyclopropenilium cations with dialkylamino and methylsulfanyl groups in the small cycle are successfully used in organic synthesis as diferrocenyl-substituted three-carbon building blocks [1]- [7]. Reactions of such cations with carbon and nitrogen nucleophiles, which proceed via the opening of the threemembered cycle and the formation of diferrocenylvinylcarbenes, have been described [1]- [13].…”

“…Reactions of such cations with carbon and nitrogen nucleophiles, which proceed via the opening of the threemembered cycle and the formation of diferrocenylvinylcarbenes, have been described [1]- [13]. On the basis of intramolecular transformations of such carbenes, researchers have developed new methods of synthesizing fiveand six-membered carbo-and heterocycles, polyene compounds with two ferrocene substituents and functional groups in the molecules [4]- [13].…”

Synthesis of diisopropylcyclopropenone and X-ray structure of its dichlorodimethyltin(IV) adduct

“…1 The most versatile route to cyclopropenones involves the dehydrobromination of α,α'-dihaloketones by a modified Favorskii reaction. 2 We had noted that the precursor to prepare the α,α'-dihaloketone for conversion to diisopropylcyclopropenone (1), 2,6-dimethyl-4-heptanone, is significantly cheaper than the precursor for the ditertbutyl analogue, 2,2,6,6-tetramethyl-4-heptanone, and since we would expect the diisopropyl analogue 1 to be particularly useful due to the additional stereochemical information that isopropyl groups can provide, we were surprised that the only reference to 1 occurs in a 1969 paper by Ciabattoni and Nathan.…”