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Updated: Jun 5, 2025

A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis
Published on: February 16, 2020
Ring Opening of Diketene in Superacidic Media
Sebastian Steiner1, Ulli Blumenschein1, Zurwa M Shafiq1
1Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, 81377 Munich, Germany.
Abstract:
The reactions of diketene were investigated in the HF/MF5 and DF/MF5 (M = As or Sb) binary superacidic systems. Depending on the stoichiometric ratio of the Lewis acids and diketene, monoprotonated acetoacetyl fluoride and diprotonated acetoacetyl fluoride were obtained. The salts were characterized by low-temperature vibrational spectroscopy, nuclear magnetic resonance spectroscopy, and single-crystal X-ray diffraction. [CH3C(OH)CH2COF][SbF6]·HF crystallizes in monoclinic space group P21/n with four formula units per unit cell, and [CH3C(OH)CH2C(OH)F][SbF6]2·HF in triclinic space group P1 with two formula units per unit cell. Ring opening is discussed together with quantum chemical pKa calculations. Monoprotonated acetoacetyl fluoride is characterized by a six-membered ring-like structure containing an intramolecular hydrogen bond, whereas the diprotonated species constitutes a 1,3-gitonic superelectrophile.
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