ChemInform Abstract: Acylation of 1,3‐Butadiene by Acetyl Fluorosulfonate.

Abstract

103ChemInform Abstract Acetyl fluoride (I) reacts with SO3 to give the acetyl fluorosulfonate mentioned in the title. This intermediate reacts in situ with butadiene (II) to give 1-acetyl-2-fluorosulfonyl-3-butene, which, on treatment with NEt3, eliminates fluorosulfonic acid to yield acetylbutadiene (III), which is known to be a versatile reagent.

Interplay of Theory and Experiment: Reversal of the Torquoselectivity of the Electrocyclic Ring Opening of 3-Acetylcyclobutene by a Lewis Acid

“…When acetylcyclobutene ( 1 ) was heated in benzene- d 6 in a sealed NMR tube at the reflux temperature overnight, it gave ( E )-3,5-hexadien-2-one ( 20 ) almost exclusively. This diene 20 has a 1 H-NMR spectrum identical to the reported data . However, this result does not necessarily signify a kinetic preference of the ring opening of 1 due to the expected ease of isomerization of the ( Z )-3,5-hexadien-2-one ( 21 ).…”

“…The product ratios were determined directly by integration of the singlet signals from the acetyl protons of the resulting E -diene 20 and Z -diene 21 in the 1 H-NMR spectra of the reaction mixtures. The dienes 20 and 21 were identified on the basis of the reported 1 H-NMR spectrum data. , Thermolyses were conducted in duplicate, and the results were observed to be reproducible.…”