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Updated: May 18, 2026

Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
On the interaction of acetone with electrophilic metallocavitands having extended cavities
Christian N Garon1, Maxime Daigle, Isabelle Levesque
1Département de Chimie, Université Laval, 1045 Avenue de la Médecine, Québec, Québec, Canada, G1 V 0A6.
Abstract:
We report the synthesis and characterization of tantalum-boronate trimetallic clusters of general formula {[Cp*Ta](3)(μ(2)-RB(O)(2))(3)(μ(2)-OH)(μ(2)-O)(2)(μ(3)-OH)} (R= 4-(C(6)H(5))(C(6)H(4)) (Ta(3)-4Ph), 4-(C(6)H(5)O)(C(6)H(4)) (Ta(3)-4OPh), 4-(C(7)H(7)O)(C(6)H(4)) (Ta(3)-4OBn), 4-(C(8)H(5))(C(6)H(4)) (Ta(3)-4PhEt), and 4-(C(12)H(7))(C(6)H(4)) (Ta(3)-4Napht)). All complexes have been characterized by NMR spectroscopy and X-ray diffraction. The trimetallic species feature a large Lewis acid type cavity allowing for substrate binding in both the solid and the liquid state using a unique electrostatic interaction and a hydrogen bond. ΔH° and ΔS° values for association of acetone with the complexes vary between -2.0 and -4.1 kcal·mol(-1) and -3 and 2 cal·mol(-1)·K(-1), respectively, showing weaker binding than smaller cavitands of the same type. The barrier for acetone exchange at equilibrium is similar for all complexes, and ΔH(‡) values vary between 8.2 and 11.4 kcal·mol(-1).
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