Manifestations of Bridgehead-Bridgehead Interactions in the Bicyclo[1.1.1]pentane Ring System.
A series of 3-halo-substituted bicyclo[1.1.1]pentane-1-carboxylic acids 1 (Y = COOH; X = F, Cl, Br, I, and CF(3)) as well as the parent compound 1 (Y = COOH, X = H) have been prepared, and a study of some of their properties have been made. It was found that their reactions with xenon difluoride cover a wide range of reactivities. On one hand, the fluoro acid 1 (Y = COOH, X = F) displayed no apparent reaction at all while, on the other, the bromo acid 1 (Y = COOH, X = Br) and parent compound 1 (Y = COOH, X = H) underwent ready reaction with complete disintegration of the ring system. A possible explanation is advanced based on polar kinetic and thermodynamic effects governing the lifetime of an intermediate acyloxy radical species. The relative ease of oxidation of the carboxylates 1 (Y = COO(-); X = H, F, Cl, Br, I, CF(3), and COOCH(3)), as mirrored by their peak oxidation potential values (E(p)) determined by cyclic voltammetry, also covers a wide range. These data coupled with the dissociation constants (pK(a)) of some of the acids 1 (Y = COOH; X = H, F, Cl, and CF(3)) reflect significantly on the modes of transmission of electronic effects acting through the bicyclo[1.1.1]pentane ring system.
Adcock
William
W
Department of Chemistry, The Flinders University of South Australia, Adelaide, Australia, 5001, Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, Department of Chemical Sciences, Deakin University, Geelong, Victoria, Australia 3217, Laboratoire a' Electrochimie Moléculaire de L'Université Denis Diderot (Paris 7), 2 place Jussieu, 75251 Paris Cedex 05, France, and Institute of Chemical Technology, Prague, Czech Republic.
Blokhin
Andrei V.
AV
Elsey
Gordon M.
GM
Head
Nicholas H.
NH
Krstic
Alexander R.
AR
Levin
Michael D.
MD
Michl
Josef
J
Munton
Jamie
J
Pinkhassik
Evgueni
E
Robert
Marc
M
Savéant
Jean-Michel
JM
Shtarev
Alexander
A
Stibor
Ivan
I