98122-97-5Relevant academic research and scientific papers
Mn(III)-based oxidative radical ring-expansion reaction using squarate derivatives: Selective synthesis of bis(butenolide)s and the acetate monomers
Sasaki, Jun-Ichi,Kobayashi, Makoto,Ibe, Y?suke,Nishino, Hiroshi
, p. 958 - 988 (2019/08/01)
The Mn(III)-based oxidation of phenyl- and alkyl-substituted hydroxycyclobutenones selectively produced the bis(butenolide)s or the acetate monomers via the 5-endo radical cyclization depending upon the concentration of the reaction. A similar reaction of hydroxycyclobutenones bearing an alkenyl and alkynyl substituent did not produce any bis(butenolide)s or acetate monomers, but the 5-exo and 6-endo radical cyclization products including the unsaturated group. The oxidation of the hydroxycyclobutenones having an unsaturated substituent in the presence of alkenes afforded radical coupling products during the 5-exo radical cyclization. The reaction details, structure determination of the products, and the mechanism for the formation of the products are described.
An efficient flow-photochemical synthesis of 5H-furanones leads to an understanding of torquoselectivity in cyclobutenone rearrangements
Harrowven, David C.,Mohamed, Mubina,Goncalves, Theo P.,Whitby, Richard J.,Bolien, David,Sneddon, Helen F.
supporting information; experimental part, p. 4405 - 4408 (2012/06/18)
Go with the flow: 4-Hydroxycyclobutenones were efficiently transformed into 5H-furanones using an inexpensive flow-photochemical setup. The results challenge the notion that this and the related thermochemical rearrangement display torquoselectivity in th
New insights into cyclobutenone rearrangements: A total synthesis of the natural ROS-generating anti-cancer agent cribrostatin 6
Mohamed, Mubina,Gon?alves, Théo P.,Whitby, Richard J.,Sneddon, Helen F.,Harrowven, David C.
supporting information; experimental part, p. 13698 - 13705 (2012/01/05)
Aryl- and heteroarylcyclobutenone rearrangements proceed in excellent yield under continuous-flow conditions. The former shows a Hammett correlation with σI providing strong evidence that electrocyclisation is the rate-determining step and has a late transition state. The reaction has been modelled by using DFT and CCSD(T) methods, with the latter giving excellent correlation with the experimental rate constant. A short and efficient total synthesis of cribrostatin 6, an anti-neoplastic and anti-microbial agent, provides a topical demonstration of the value of this method.
A Potentially General Regiospecific Synthesis of Substituted Quinones from Dimethyl Squarate
Gayo, Leah M.,Winters, Michael P.,Moore, Harold W.
, p. 6896 - 6899 (2007/10/02)
A potentially general regiospecific synthesis of benzo- and naphthoquinones is described.This method starts with dimethyl squarate (1) which is converted to the cyclobutenone ketal 3 upon sequential treatment with an organolithium reagent and then BF3 etherate or TFAA in THF/methanol.Treatment of these with a second lithium reagent followed by hydrolysis gives the cyclobutenones 5.Addition of an alkynyl-, alkenyl- or aryllithium agent to 5 followed by hydrolysis of the ketal linkage gives the corresponding 4-alkynyl-, 4-alkenyl- or 4-aryl-4-hydroxycyclobutenones7 - 9, and these readily rearrange to the respective quinones or hydroquinones upon thermolysis in refluxing benzene.In a similar fashion, 15 was employed as a reagent to prepare mono- and disubstituted hydroquinones and quinones.
PHOTOLYSIS OF 4-SUBSTITUTED-4-HYDROXY-3-CYCLOBUTEN-1-ONES: A NEW ROUTE TO BUTENOLIDES FROM 4-HYDROXYCYCLOBUTENONES
Perri, Steven T.,Foland, Lafayette D.,Moore, Harold W.
, p. 3529 - 3532 (2007/10/02)
Photolysis of 4-substituted-4-hydroxy-3-cyclobuten-1-ones undergo electrocyclic ring opening followed by ring closure to provide butenolide products.This transformation is envisaged to involve a stereoselective disrotatory electrocyclic ring opening to co
Synthesis of 4-Substituted-3-alkoxy-3-cyclobutene-1,2-diones
Reed, Michael W.,Pollart, Daniel J.,Perri, Steven T.,Foland, Lafayette D.,Moore, Harold W.
, p. 2477 - 2482 (2007/10/02)
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
General Regiospecific Synthesis of Annulated Quinones
Moore, Harold W.,Perri, Steven T.
, p. 996 - 1003 (2007/10/02)
A general regiospecific synthesis of annulated hydroquinones/quinones is presented.This specifically involves the thermal rearrangement of the 4-aryl-4-hydroxycyclobutenones 1a-k to the corresponding annulated hydroquinones.The synthetic scope and mechani
REACTIVITY OF ORGANO LITHIUM REAGENTS ON DIMETHYL SQUARATE: A 1,2-ADDITION PROCESS LEADING TO NEW 1-HYDROXY-3,4 DIMETHOXY 3-CYCLOBUTENONE
Kraus, Jean Louis
, p. 1867 - 1870 (2007/10/02)
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.
