Relative reactivities and stereochemistry of addition of iodoperfluoroalkanes to cyclic olefins

Abstract

The relative reactivity of cyclic olefins toward the free-radical addition of 1-iodoperfluoropropane at 70°u sing azonitrile initiator was ci's-cyclooctene (2.70) > cyclopentene (2.22) > cycloheptene (1.40) > cyclohexene (1.00). Under these conditions 1-heptene (a typical acyclic olefin) reacted 14 times faster than cyclohexene. cis-Cyclooctene gave four adducts: cis-and transl-iodo-2-perfluoropropylcyclooctane and, by 1,5 shift of the intermediate radical, cis-and frans-l-iodo-4-perfluoropropylcyclooctane. Zinc reduction of this mixture gave only perfluoropropylcyclooctane, and dehydrohalogenation formed two olefins in nearly equal amounts. By contrast, cyclopentene gave only a trans adduct, while cyclohexene and cycloheptene formed both cis and trans 1,2 adducts, probably as a result of ring flipping. These results are interpreted as the consequence, first, of preferred trans addition (with the bulky and electronegative Rt and iodine groups as far as possible from each other) and, secondly, a combination of steric strain and pseudorotation of the rings.

Mixing of Partially Fluorinated Carboxylic Acids with Their Hydrocarbon Analogs at the Air–Water Interface

“…The partially fluorinated acids 1-3 were synthesized as described earlier and their spectroscopic data are in agreement with the proposed structure (Scheme 1) (27)(28)(29). Their purity as determined by gas chromatography was >99% (based on relative peak area).…”

Synthesis of Difluoromethylene-Containing 1,2,4-Oxadiazole Compounds via the Reaction of 5-(Difluoroiodomethyl)-3-phenyl-1,2,4-oxadiazole with Unsaturated Compounds Initiated by Sodium Dithionite

“…The NMR signal of the proton CHI exhibited a quartet at d = 4.43 (J = 6.0 Hz) with coupling to adjacent R F CH and CH 2 that closely resembled those of the polyfluoroalkyl analogue characterized previously. 26,27 Free radical addition of 4 in the trans mode to cyclopentene conformed to the pattern observed in reactions of this type, since the cis-adduct would have considerable crowding of the bulky and electronegative R F and I groups. 26,27 When diallyl ether 11 was used as the substrate, tetrahydrofuran derivative 12 was obtained as a mixture of transand cis-isomers in 3.3:1 ratio, indicating a radical mechanism ( Table 2, entry 13).…”

“…As previously shown, the reaction proceeded by trans and cis addition, since flipping of the ring 8 formed at first to 8¢ may occur before transfer of the intermediate radical with R F I 4 (Figure 1). 26 In the case of cyclopentene (9), only the trans-isomer 10 was detected ( Table 2, entry 12). The NMR signal of the proton CHI exhibited a quartet at d = 4.43 (J = 6.0 Hz) with coupling to adjacent R F CH and CH 2 that closely resembled those of the polyfluoroalkyl analogue characterized previously.…”

Mixing behavior of 10-(perfluorohexyl)-decanol and DPPC

“…10-(Perfluorohexyl)-decanol was synthesized by free radical coupling of perfluorohexyliodide and 9-decenoic acid methyl ester [17][18][19]. Its characterization and purity has been described previously [8].…”