Fluorinated cyclopropenes and cyclopropenium ions

Structure, Synthesis, and Chemical Reactions of Fluorinated Cyclopropanes and Cyclopropenes

“…Law and Tobey attributed the decrease in reactivity for C 3 X 2 F 2 (X ) Br or Cl) to a decrease in ring strain as a result of increased s-character in the ring C-C bonds. 202 Essentially the same conclusion was reached by Wiberg some 30 years later on the basis of ab initio calculations (see isodesmic equation 4 and Table 3). 11 Taken together, the geminal fluorine effect and the effect of polar substitution at the methylene carbon adequately account for the sluggish reactivity of 3,3-difluorocyclopropene with cylopentadiene.…”

“…It should be mentioned that this trifluorocyclopropene (102) has also been prepared by the halogen-exchange method of West and co-workers. 202 Other pertinent examples of the dehydrohalogenation method to make fluorinated cyclopropene include the isolation of 3,3-difluorocyclopropene in low overall yield (10%) by passing 1-chloro-2,2-difluorocyclopropane through an ascarite (NaOH on asbestos) column at room temperature (not recommended for synthetic purposes) 203 and the basepromoted elimination of HCl from the dichlorocyclopropane adduct formed in situ from the addition of dichlorocarbene to 2,2-difluorostyrene under phase transfer conditions (40% aqueous NaOH, benzyltriethylammonium chloride). 204 The yield of cyclopropene 103 was 55%.…”

“…188,224,225 The cycloadducts of tetrachlorocyclopropene and 3,3-difluoro-1,2-dichlorocyclopropene with 1-substituted and 1,4-disubstituted 1,3-butadienes have been similarly determined to have the exo configuration. 224,226,227 Almost simultaneously with the Law and Tobey report, 202 Sargeant reported the [4 + 2] cycloaddition reactions of perfluorocyclopropene (101) and perfluoro-1,2-dimethylcyclopropene (82) with cyclopentadiene and furan at room temperature. 182 In the case of 101, both tricyclic adducts 125 (X ) O or CH 2 ) were assigned the endo structure, but again the evidence (NMR chemical shifts) is unconvincing.…”

Difluorocarbene Chemistry: A Simple Transformation of 3,3‐gem‐Difluorocyclopropenes to Cyclopropenones†

“…18 On the other hand, acetyl group could be re- 19 According to these reports, the reaction of 2 with BF 3 •Et 2 O was carried out. It was found that treatment of 2 with a catalytic amount of BF 3 •Et 2 O (0.2 equiv.)…”

Cyclopropenium (C3H3)+ as an Aromatic Alternative A-Site Cation for Hybrid Halide Perovskite Architectures

“…Here we describe an aprotic , all-hydrocarbon hybrid intercalator by drawing on non-benzenoid arene chemistry . The (C 3 H 3 ) + cation possesses Hückel aromaticity and has been isolated in both the hydrogenic and halogenated forms. − The parent (C 3 H 3 ) + ion can be synthesized by Lewis acid mediated chloride elimination from C 3 H 3 Cl or elimination of carbon monoxide and methanol by the action of Brønsted acid on cyclopropenyl ester C 3 H 3 CO 2 CH 3 . While these carbocations are remarkably stable in solution phase, the stability should not grossly differ as their stability depends on their surrounding dielectric medium.…”