158599-29-2

Upstream product

• 591-51-5 phenyllithium 
• 5231-87-8 3,4-diethoxy-3-cyclobuten-1,2-dione 

Downstream Products

• 69009-17-2 3,4,4-triethoxy-2-phenyl-2-cyclobutenone 
• 170117-98-3 2,3,4-triethoxy-4-phenyl-2-cyclobutenone 
• 170118-00-0 3,4-diethoxy-2-phenyl-4-(2-propenyl)-2-cyclobutenone 
• 178418-83-2 4-ethoxy-3-methyl-2-phenyl-4-(2-propenyl)-2-cyclobutenone 

Relevant academic research and scientific papers

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

New Method for Derivatization of Squaric Acid to Highly Substituted Cyclobutenones: Lewis Acid-Catalyzed Reaction of Cyclobutene-1,2-dione Monoacetal and Its Vinylog with Unsaturated Organosilanes, and Subsequent Ring Transformation of the Adducts

Described herein is a novel method for regio-controlled synthesis of highly substituted cyclobutenones having an unsaturated substituent at 4-position, starting from commercially available squaric acid. Both cyclobutene-1,2-dione monoacetal (4,4-diethoxycyclobutenone) and its vinylog (2,4-diethoxycyclobutenone), which were easily obtained from diethyl squarate, reacted with allylsilanes in the presence of Et2O-BF3 to afford 4-allyl-4-ethoxycyclobutenones having various substituents at 2-position regioselectively. These products were efficiently transformed to highly substituted bicyclo[3.2.0]heptenones by refluxing in xylene. The synthetic utility of this process was demonstrated in the construction of tricyclic ring systems. Further extension of the Lewis acid-catalyzed reaction of the monoacetal using an allenylsilane, a silyl enol ether, and a silyl ketene acetal also afforded the corresponding 4-substituted products. In contrast to the above 4-allylated products, 4-propargylated and 4-acylmethylated products did not undergo an analogous ring transformation under the same conditions.

Oxidative Rearrangement of 4-Hydroxy-2-cyclobutenone. A New Route to Highly Substituted Furanones from Squaric Acid

4-Hydroxy-2-cyclobutenones, which were obtained by the reaction of diethyl squarate with an organolithium, reacted with lead tetraacetate (to generate an oxy radical) affording 5-acetoxy-2(5H)-furanones and 5-alkylidene-2(5H)-furanones.This type of rearrangement was realized in a simple four-membered cyclic α-ketol but not in the corresponding five-membered ring.