711-78-4

Upstream product

• 67-56-1 methanol 
• 22315-46-4 bromo-phenyl-cyclobutenedione 
• 313-28-0 3,3,4,4-Tetrafluor-1-phenyl-cyclobuten-⁽¹⁾ 
• 313-29-1 4-Fluor-4-chlor-1-phenyl-cyclobuten-⁽¹⁾-on-⁽³⁾ 
• 313-30-4 4,4-Difluoro-3-phenyl-cyclobuten-⁽²⁾-on-⁽¹⁾ 
• 313-27-9 1-phenyl-3,3,4-trifluoro-4-chloro-1-cyclobutene 
• 3947-97-5 3-phenyl-3-cyclobutene-1,2-dione 
• 71-43-2 benzene 
• 853660-78-3 4-hydroxy-3-methoxy-2-phenyl-2-cyclobuten-1-one 
• 5222-73-1 3,4-dimethoxy-3-cyclobutene-1,2-dione 
• 98122-97-5 2,3-dimethoxy-4-hydroxy-4-phenyl-2-cyclobuten-1-one 
• 591-51-5 phenyllithium 
• 883-15-8 Phenyl-methoxy-dichlor-cyclobutenon 
• 186581-53-3 diazomethane 

Downstream Products

• 708-10-1 3-phenyl-4-hydroxycyclobut-3-ene-1,2-dione 
• 112597-36-1 4-hydroxy-3-methoxy-4-(N-methyl-2-pyrrolyl)-2-phenylcyclobutenone 
• 17204-78-3 3-Ethyl-4-phenyl-3-cyclobuten-1,2-dione 
• 34667-97-5 3-methyl-4-phenylcyclobut-3-ene-1,2-dione 
• 81399-98-6 (Z)-3-(3-Hydroxy-4-oxo-2-phenyl-2-cyclobuten-1-ylidenmethyl)-4-phenyl-3-cyclobuten-1,2-dion 
• 142700-52-5 1-Hex-1-ynyl-3-methyl-2-phenyl-4-[1-phenyl-meth-(E)-ylidene]-cyclobut-2-enol 
• 142700-53-6 1-Hex-1-ynyl-3-methyl-2-phenyl-4-[1-phenyl-meth-(Z)-ylidene]-cyclobut-2-enol 
• 142700-54-7 3-Methyl-2-phenyl-4-[1-phenyl-meth-(E)-ylidene]-1-vinyl-cyclobut-2-enol 
• 142700-55-8 3-Methyl-2-phenyl-4-[1-phenyl-meth-(Z)-ylidene]-1-vinyl-cyclobut-2-enol 
• 142700-56-9 1,3-Dimethyl-2-phenyl-4-[1-phenyl-meth-(E)-ylidene]-cyclobut-2-enol 

Relevant academic research and scientific papers

Four-Electron Electrocyclic Ring-Opening/Intermolecular [4+2] Cycloadditions of α-Hydroxycyclobutenones: Stereoselective Synthesis of Multiple Substituted δ-Lactams

A four-electron electrocyclic ring-opening/intermolecular [4+2] cycloaddition of α-hydroxycyclobutenones is reported. The reaction represents the first example for the intermolecular cycloaddition of the extensively studied enol-ketene intermediate, and provides a new synthetic route to multiply substituted δ-lactams in high stereoselectivity.

New synthesis of semisquaric acid derivatives via chlorinated N-(cyclobutylidene)amines

The synthesis and reactivity of new chlorinated AT-(cyclobutylidene)amines leading to new synthetic pathways toward various substituted cyclobutenediones is described.

Synthesis of 2(5H)-furanones via oxidative ring expansion of 4-hydroxy-2-cyclobutenones

A new method to reduce cyclobutenediones towards 4-hydroxy-2-cyclobutenones was established. The latter compounds gave rise to new 5-halo-2(5H)-furanones by reaction with halogenating agents via a cationic ring-opening-ring-closure mechanism.

Selective 1,4-addition of arenes to 3-chloro-3-cyclobutene-1,2-dione under friedel-crafts conditions. Synthesis and reactivity of 4-aryl-3-chloro-2- hydroxy-2-cyclobuten-1-ones

The reaction of semisquaric chloride (7) with arenes 2 has been investigated. In the presence of 1.1 equiv of AlCl3 and in the temperature range of -15° C to rt the arenes 2a-q afford the 4-aryl-3-chloro-2-hydroxy-2-cyclobuten-1-ones (chloroenols) 8a-q in good yield. By contrast, 7 reacts with 1,4-dimethoxybenzene (2l) in boiling CH 2Cl2 to give a mixture of (2,5-dimethoxyphenyl) cyclobutenedione (9a) (27% yield) and bis(2,5-dimethoxyphenyl)cyclobutenedione (10a) (8% yield). With 1,2,4-trimethoxybenzene (2r) in the presence of trifluoroacetic acid is generated (2,4,5-trimethoxyphenyl)-cyclobutenedione (9b) in 21% yield. The chloroenols 8 allow a series of valuable transformation reactions: with diazomethane the chloroenol methyl ethers 11 are generated, with chlorine the 3-aryl-4-chlorocyclobutenediones 12, and with bromine in MeOH the 3-aryl-4-methoxycyclobutenediones 13. In DMSO or in acetone/H2O the chloroenols 8 eliminate HCl, furnishing the arylcyclobutenediones 14. In a mixture of acetone-d6/D2O/DCl are obtained 4-aryl-cyclobutenediones-3-d 15. For the latter two processes the corresponding 3-aryl-4-chlorocyclobutane-1,2-diones 16 are postulated as intermediates. Thermolysis of the chloroenols 8 and the chloroenol methyl ethers 11 in refluxing m-xylene afforded the 3-chloro-1,2-dihydroxynaphthalenes 17 and the 3-chloro-1-hydroxy-2-methoxynaphthalenes 18, respectively.

Rearrangements of 4-Alkynyl-, 4-Alkenyl-, and 4-Alkyl-4-hydroxy-3-methylenecyclobutenes

Reported here are the thermal rearrangements of the 4-alkynyl- (1), 4-alkenyl- (7), and 4-alkyl-4-hydroxy-2-methyl-1-phenyl-3-benzylidenecyclobutene (11) to, respectively, the phenol 5, derived from the p-quinonemethide 4, the benzylidenecyclohexenone 10,

Rearrangement of 4-Alkynylcyclobutenones. A New Synthesis of 1,4-Benzoquinones

A new convergent synthesis of 1,4-benzoquinones from 4-alkynyl-4-alkoxy(or hydroxy or trimethylsilyloxy)cyclobutenones is described.The required cyclobutenones are prepared from squaric acid and converted to the quinones upon mild thermolysis.The reaction proceeds via electrocyclic ring opening of the required cyclobutenones to (2-alkynylethenyl)ketenes, which then ring close to unique diradical intermediates.These then give the quinone products.The scope and mechanism of this unusual rearrangement are discussed.

Synthesis of 4-Substituted-3-alkoxy-3-cyclobutene-1,2-diones

4-Substituted-3-alkoxycyclobutenediones 3 were obtained from dialkoxycyclobutenediones (dialkyl squarates) 1 by the addition of organolithium reagents followed by hydrolysis of the resulting hydroxycyclobutenone 2.A particularly useful one-pot procedure i

REACTIVITY OF ORGANO LITHIUM REAGENTS ON DIMETHYL SQUARATE: A 1,2-ADDITION PROCESS LEADING TO NEW 1-HYDROXY-3,4 DIMETHOXY 3-CYCLOBUTENONE

Lithium reagents react with dimethylsquarate at the carbonyl group according to a 1,2-addition process, leading to new 2-hydroxy-3,4 dimethoxy-3 cyclobutenone.