Cycloaddition reaction of quadricyclane and fluoroolefins

Reaction of quadricyclane (1) with fluoroolefins of different structure results in stereoselective formation of polyfluorinated exo-tricyclo[4.2.1.0(2.5)]non-7-enes. The reaction of a mixture of trans/cis CF3CF=CFCF3 with 1 is stereoselective and the resulting cycloadducts 7a. b preserve the original alkene stereochemistry. The relative rate constants of cycloaddition of a series of fluoroolefins to I under pseudo first-order conditions measured by kinetic NMR at 109 degrees C provide a kinetic scale of reactivities of the fluoroolefins in this reaction. These relative rate constants correlate well with the number of fluoroalkyl groups connected to the double bond, reaching a maximum for the tri-substititted olefin: CF3CF=CF2:CF3CF=CFCF3:(CF3)(2)C=C(CF3)(2):(CF3)(2)C=CFC2F5 = 1:1.2-1.9:4:138. (c) 2005 Elsevier B.V. All rights reserved.