58283-01-5

Upstream product

• 81287-10-7 3-<(E)-Hydroxyiminomethyl>-4-phenyl-3-cyclobuten-1,2-dion 
• 34667-97-5 3-methyl-4-phenylcyclobut-3-ene-1,2-dione 

Downstream Products

• 81287-14-1 3,4-Dioxo-2-phenyl-1-cyclobuten-1-carboxamid 

Relevant academic research and scientific papers

Generation of 1,2-bisketenes from cyclobutene-1,2-diones by flash photolysis and ring closure kinetics

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.

Reactions with Cyclobutenediones, LXI. Ring Expansions and Conversions of 3-Alkyl-4-phenylcyclobutenediones

In a novel reaction for the cyclobutenedione system, oxidation of the title compounds 1a and 1b leads to ring expansion with formation of cyclopentenetrione 3 and cyclopentenedione 5.The oximes 6a and b, produced by nitrosation of 1a and b, can be hydrolysed to the ring enlarged structures 4d and 5. 4d is oxidized to 3 and methylated to 7.Beckmann-conversion of 6a and b results in the formation of the amide 10 and the amine 11. 6a is acetylated to 13 or dehydrated to the nitrile 14.