Fluorocyclopropanes. III. 1,4-Cycloaddition reactions of perfluorocyclopropene and 1,2-bis(trifluoromethyl)-3,3-difluorocyclopropene

Abstract

and C4F9IF2 and confirmed many of the observations reported herein. I want to express particular appreciation to Walter G. Barber for his assistance throughout this work. His intrepid handling of C1FS demonstrated that even the most dangerous work can be performed safely. Mr. Barber also built the fluo-3061 rine-handling equipment, with assistance and advice from Edward Hancock, our resourceful mechanic.Thomas E. Beukelman performed the nmr studies, and I owe a great deal to his imaginative examination of the spectra. Dr. James Proctor conducted the X-ray study of solid Ci0F2iIF2.Fluorocyclopropanes. III. 1,4-Cycloaddition Reactions of Perfluorocyclopropene and 1,2-Bis (trifluoromethyl) -3,3-difluorocyclopropene

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

“…Also lacking is an appreciation of the remarkable instability of the cyclopentadiene adduct 125 (X = CH 2 ) toward the now familiar cyclopropyl−allyl rearrangement. Thus, as Sargeant reports, this adduct quantitatively rearranges on prolonged standing, or on attempted distillation, to the tetrafluorobicyclo[3.2.1]heptadiene 126 . Similar rearrangements occur in the cycloadductions of cyclopentadiene or furan with tetrachlorocyclopropene and tetrabromocyclopropene; however, the corresponding adducts with the 3,3-difluorodihalocyclopropenes show no propensity for this isomerization, even on heating.…”

“…Almost simultaneously with the Law and Tobey report, Sargeant reported the [4 + 2] cycloaddition reactions of perfluorocyclopropene ( 101 ) and perfluoro-1,2-dimethylcyclopropene ( 82 ) with cyclopentadiene and furan at room temperature . 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.…”

“…180 Before proceeding, mention should be made of the development in the mid-1960s, by the DuPont group, of hexafluoropropene oxide (HFPO) as an effective difluorocarbene source and their use of this reagent for the subsequent synthesis of perfluorinated 1-methyl-and 1,2-dimethylcyclopropenes. [181][182][183] The reactivity of HFPO derives from the fact that fluorine substituents destabilize an oxirane ring in a manner similar to a cyclopropane. 184 This :CF 2 precursor was also instrumental in the synthesis of perfluorocyclopropene (vide infra).…”

Computational Study of the Stereoselectivity Profiles of the Diels-Alder Cycloaddition Reactions of Cyclopentadiene and Butadiene with Cyclopropenes

“…The experimental endo and exo stereoselectivities of the DA cycloaddition reactions of cyclopentadiene with cyclopropene 1a, cyclopropenone acetal 1b, perfluorocyclopropene 1c, 1,2-dichloro-3,3-difluorocyclopropene 1d and 1,2-dibromo-3,3-difluorocyclopropene 1e are given in Scheme 1. While 1a (CH2Cl2, 0 o C) 1 and 1c (CDCl3, 25 o C) 3,4 form the endo adduct exclusively, 1d and 1e generate only the exo adduct (CCl4, 0 o C) 3 and 1b 2 exhibits no selectivity for furnishing an equal mixture of both the adducts at 25 o C under no solvent conditions. The corresponding reactions of butadiene with the cyclopropenes 1a, 1,6 1b, 2 1c, 5 1d 7 and 1e 7 are also reported in the literature.…”

Computational Study of the Stereoselectivity Profiles of the Diels-Alder Cycloaddition Reactions of Cyclopentadiene and Butadiene with Cyclopropenes

“…The experimental endo and exo stereoselectivities of the DA cycloaddition reactions of cyclopentadiene with cyclopropene 1a, cyclopropenone acetal 1b, perfluorocyclopropene 1c, 1,2-dichloro-3,3-difluorocyclopropene 1d and 1,2-dibromo-3,3-difluorocyclopropene 1e are given in Scheme 1. While 1a (CH2Cl2, 0 o C) 1 and 1c (CDCl3, 25 o C) 3,4 form the endo adduct exclusively, 1d and 1e generate only the exo adduct (CCl4, 0 o C) 3 and 1b 2 exhibits 2 no selectivity for furnishing an equal mixture of both the adducts at 25 o C under no solvent conditions. The corresponding reactions of butadiene with the cyclopropenes 1a, 1,6 1b, 2 1c, 5 1d 7 and 1e 7 are also reported in the literature.…”