154473-76-4Relevant academic research and scientific papers
Reactive iron carbonyl reagents via reaction of metal alkoxides with Fe(CO)5 or Fe2(CO)9: Synthesis of cyclobutenediones via double carbonylation of alkynes
Beesu, Mallesh,Periasamy, Mariappan
experimental part, p. 543 - 549 (2011/04/16)
Alkoxy bases such as t-BuOK react with Fe(CO)5 to give reactive iron carbonyl intermediates that in turn react with alkynes at 70 °C in THF to give 1,2-cyclobutenediones in 70-93% yields after CuCl2· 2H2O oxidation. A novel 1,2-diacyloxyferrole derivative was isolated in the reaction of diphenylacetylene with Fe(CO)5/t-BuOK in the presence of acetyl chloride in contrast to the formation of a 1,4-diacyloxyferrole complex formed in the reaction using Fe(CO) 5/Me3NO. The Fe2(CO)9/t-BuOK reagent system also converts the alkynes to corresponding cyclobutenediones in 63-90% yields under similar reaction conditions.
Generation of 1,2-bisketenes from cyclobutene-1,2-diones by flash photolysis and ring closure kinetics
Allen, Annette D.,Colomvakos, Jim D.,Diederich, Fran?ois,Egle, Ian,Hao, Xiaokuai,Liu, Ronghua,Lusztyk, Janusz,Ma, Jihai,McAllister, Michael A.,Rubin, Yves,Sung, Kuangsen,Tidwell, Thomas T.,Wagner, Brian D.
, p. 12125 - 12130 (2007/10/03)
The interconversion of cyclobutene-1,2-diones (1) and 1,2-bisketenes (RC-C-O)2 has been surveyed for different combinations of substituents R = H, Me, t-Bu, Ph, Me3Si, CN, Cl, Br, R1O, alkynyl, and PhS. The bisketenes 2 have been generated by flash photolysis, and the kinetics of their conversion to 1 have been studied by time-resolved infrared and ultraviolet spectroscopy. The rate constants of the ring closure of 2 are correlated by the ketene stabilization parameters (SE) and with calculated barriers. The rate constant of ring closure of the di-tert-butyl bisketene 2g to cyclobutenedione 1g is only 40 times smaller than for the dimethyl analogue, showing a rather modest steric barrier. The quinoketene 2s has a fast rate of ring closure, but not as fast as anticipated on the basis of calculated geometric and thermodynamic factors. A lag in the attainment of aromatic stabilization in the transition structure for ring closure is a possible cause of this diminished reactivity.
Aryl substituent effects on the thermal interconversion of cyclobutenediones and 1,2-bisketenes
Liu, Ronghua,Tidwell, Thomas T.
, p. 2757 - 2762 (2007/10/03)
The rates and activation parameters are reported for ring closure of 1,2 bisketenes O=C=C(C6H4X)C(SiMe3)=C=O (7), generated by photolysis of the corresponding cyclobutenediones 6. The rates at 70°C are correlated with the
