91680-95-4

Upstream product

• 64-17-5 ethanol 
• 36394-22-6 4-hydroxy-5-phenyl-4-cyclopentene-1,3-dione 

Downstream Products

• 91680-96-5 2-<1-(4-Chlorphenyl)-3-oxo-butyl>-4-ethoxy-5-phenyl-cyclopent-4-en-1,3-dion 
• 91680-97-6 2-<1-(4-Chlorphenyl)-3-oxo-butyl>-4-hydroxy-5-phenyl-cyclopent-4-en-1,3-dion 
• 91680-92-1 2-(4-Chlorbenzyl)-4-hydroxy-5-phenyl-cyclopent-4-en-1,3-dion 
• 36394-22-6 4-hydroxy-5-phenyl-4-cyclopentene-1,3-dione 

Relevant academic research and scientific papers

Ring expansion of diazo-functionalized 4-hydroxycyclobutenone: Catalytic ring opening and recyclization to 2(5H)-furanone/cyclopentenedione and thermal 4π-8π electrocyclic ring opening-closure to diazepinedione

The acid-catalyzed and Rh-catalyzed (also photolyzed) decomposition of 4-hydroxycyclobutenones with a diazo group at C-4 gave 2(5H)-furanone and/or cyclopentene-1,3-dione via an α-carbocation intermediate and a carbenoid (carbene) intermediate, respectively. Thermal rearrangement of some of these compounds led to the formation of diazepinediones without the extrusion of nitrogen through tandem 4π electrocyclic ring opening and 8π electrocyclic ring closure processes.

Radical-mediated ring enlargement of cyclobutenones: New synthetic potential of squaric acid

4-Hydroxy-2-cyclobutenones, which are readily obtainable from diethyl squarate, reacted with lead tetraacetate to give 5-acetoxy-2(5H)-furanones and 5-alkylidene-2(5H)-furanones via oxy-radical-triggered ring opening (β-scission) and subsequent 5-endo rec