3947-97-5

Usage

Synthesis Reference(s)

Synthetic Communications, 25, p. 2781, 1995 DOI: 10.1080/00397919508011825

InChI:InChI=1/C10H6O2/c11-9-6-8(10(9)12)7-4-2-1-3-5-7/h1-6H

Upstream product

• 313-27-9 1-phenyl-3,3,4-trifluoro-4-chloro-1-cyclobutene 
• 79-38-9 Chlorotrifluoroethylene 
• 536-74-3 phenylacetylene 
• 91359-10-3 2-Chloro-3-phenyl-4-phenylsulfanyl-cyclobut-2-enone 
• 591-51-5 phenyllithium 
• 114094-78-9 4-(tert-butyldimethylsiloxy)-2,3-bis(1-methylethoxy)cyclobut-2-en-1-one 
• 786-02-7 1,1-Difluor-2,2-diethoxy-3-phenyl-cyclobuten 
• 787-18-8 1,1-Difluor-2,4-diethoxy-3-phenyl-cyclobuten 
• 3470-35-7 4,4-dichloro-3-phenyl-2-cyclobuten-1-one 
• 175225-79-3 3-chloro-2-hydroxy-4-phenyl-2-cyclobuten-1-one 
• 109-73-9 N-butylamine 
• 15321-51-4 diiron nonacarbonyl 
• 13463-40-6 iron pentacarbonyl 
• 342-60-9 2,4-dichloro-1,1-difluoro-3-phenyl-2-cyclobutene 

Downstream Products

• 100518-82-9 2,4-dimethoxy-3-phenyl-cyclobutenone 
• 22315-46-4 bromo-phenyl-cyclobutenedione 
• 22118-93-0 3-chloro-4-(4-phenyl)cyclobut-3-ene-1,2-dione 
• 19173-47-8 4-p-Toluolsulfonyl-hydrazino-2.3-dioxo-1-phenyl-cyclobutan 
• 21234-73-1 1-Methoxy-3-dimethylphosphoryl-4-oxo-2-phenylcyclobuten-⁽¹⁾ 
• 148992-73-8 3,4-diphenyl-2-(1,3,6-trioxaheptyl)-2-cyclobutenone 
• 56076-28-9 4-(2,5-Dimethoxy-phenyl)-2-hydroxy-3-phenyl-cyclobut-2-enone 
• 55977-42-9 3-phenyl-4-(toluene-4-sulfonyl)-cyclobutane-1,2-dione 
• 24804-65-7 1-<4-Fluor-phenyl>-2-phenyl-cyclobuten-(2)-ol-(3)-on-(4) 
• 24863-30-7 3-Hydroxy-2-phenyl-1-<4-brom-phenyl>-cyclobuten-(2)-on-(4) 
• 62823-24-9 4-(2-Fluorenyl)-2-hydroxy-3-phenyl-2-cyclobuten-1-on 
• 24804-67-9 3-Hydroxy-2-phenyl-1--cyclobuten-(2)-on-(4) 
• 59735-56-7 3-Bromo-benzoic acid 3-chloro-4-oxo-2-phenyl-cyclobut-1-enyl ester 
• 23094-25-9 2-Benzoyloxy-3-phenyl-4-brom-cyclobuten-⁽²⁾-on 

Relevant academic research and scientific papers

Novel reaction of the [HFe3(CO)11]- reagent with alkynes: A new synthesis of cyclobutenediones

Reaction of the [HFe3(CO)11]- species generated in situ using Fe(CO)5 and NaBH4/CH3COOH in THF with alkynes, followed by CuCl2.2H2O oxidation leads to the corresponding cyclobutenediones in 60-73% yields.

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

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.

A simple and convenient method for the synthesis of cyclobutenediones from alkynes using new Fe(CO)5/NaH/MeI reagent system

Iron carbonyl complexes prepared in situ using the Fe(CO)5/NaH/MeI reagent combination and alkynes at 25 °C give the corresponding cyclobutenediones in 50-65% yields after CuCl2 · 2H2O oxidation.

Amine induced carbonylation of alkynes to cyclobutenediones using Fe3(CO)12

Iron carbonyl species, prepared in situ in THF using Fe3(CO)12, react with alkynes at 25°C, in the presence of certain amines, to give the corresponding cyclobutenediones in moderate to good yields (25-61%) after CuCl2·2H

New Convenient One-Pot Methods of Conversion of Alkynes to Cyclobutenediones or α,β-Unsaturated Carboxylic Acids Using Novel Reactive Iron Carbonyl Reagents

Reactions of NaHFe(CO)4/RX or [HFe3(CO)11]- reagents with alkynes lead to the formation of the corresponding α,β-unsaturated carboxylic acids and/or the cyclobutenediones. The reagent generated in situ using the NaHFe(CO)4/CH3I combination in THF, on reaction with alkynes followed by CuCl2·2H2O oxidation, gives the corresponding cyclobutenediones (27-42%) and α,β-unsaturated carboxylic acids (10-22%), whereas the reagent generated using CH2Cl2 in place of CH3I leads to α,β-unsaturated carboxylic acids (37-60%) and their derivatives (35-55%) at 25°C. The same reagent system in the presence of acetic acid (4 equiv) yields the corresponding cyclobutenedione (33%). The reaction using Me3SiCl gives the corresponding α,β-unsaturated carboxylic acids (45-54%) at 25°C and the corresponding cyclobutenediones (51-63%) at 60°C. Interestingly, the reaction of the [HFe3(CO)11]- species generated using Fe(CO)5/NaBH4/CH3COOH, with alkynes at 25°C, followed by CuCl2·2H2O oxidation gives the corresponding cyclobutenediones (60-73%). The possible intermediates and pathways for the formation of α,β-unsaturated carboxylic acids and cyclobutenediones are discussed.

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.

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.

Facile addition of dichloroketene to acetylenes mediated by zinc and ultrasound

The addition of dichloroketene, generated from trichloroacetyl chloride, zinc dust and ultrasound, to terminal and internal acetylenes is reported. This procedure is a more convenient alternative to Zn-Cu couple.

A new process for the regiocontrolled synthesis of substituted catechols and other 1,2-dioxygenated aromatics: Conjugate addition of vinyl-, aryl-, and heteroarylcopper reagents to cyclobutenediones followed by thermal rearrangement

A general method for the synthesis of substituted catechol derivatives has been developed utilizing the 1,4-addition of vinyl-, aryl-, and heteroarylcuprates to cyclobutenediones followed by thermal rearrangement. In situ protection with (methoxyethoxy)methyl chloride of the enolate derived from addition of the cuprate yields 2-alkoxy-4-Runsat'd-2-cyclobutenones, which rearrange thermally to substituted catechols with differentiated hydroxy groups. Monosubstituted cyclobutenediones undergo highly regioselective 1,4-addition at the unsubstituted carbon; alternatively, regiocontrol can be exerted by addition to cyclobutenedione monoacetals. Differentially disubstituted cyclobutenedione monoacetals undergo regiospecific 1,4-addition to the unprotected enone moiety. Protection of the intermediate enolate and mild hydrolysis of the acetal yield 3,4-disubstituted 2-alkoxy-4-RUnsat'd-2-cyclobutenones regiospecifically. Thermolysis of these products delivers substituted catechol monoethers regiospecifically.