106. P. Müller, G. Bernardinelli, J. Pfyffer, J.-P. Schaller,
     “Stereo and Face Selectivity in Cycloadditions of 1,2,3-Trichloro-3-fluorocyclopropenes to Acyclic Dienes and Furans”
     Helv. Chim. Acta 1991, 74, 993-1001.

The stereo and face selectivities of the cycloaddition of 1,2,3-trichloro-3-fluorocyclopropene (1a) with acyclic dienes and furans has been re-investigated by X-ray determination and correlation of ¹⁹F-NMR data. The isolated adducts of dienes exclusively have exo-configuration, and exo-Configuration predominates with furans. The Cl substituents of the resulting cyclopropane ring are cis-oriented. The face selectivity of the reaction with both types of substrates is attributed to electrostatic interactions between the F and the bridgehead Cl substituents, which destabilize the F-cis-transition state (13 (F-cis)) over 13 (F-trans).

DOI : 10.1002/hlca.19910740510 

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