1121-15-9Relevant academic research and scientific papers
Four-Electron Electrocyclic Ring-Opening/Intermolecular [4+2] Cycloadditions of α-Hydroxycyclobutenones: Stereoselective Synthesis of Multiple Substituted δ-Lactams
Song, Peidong,Li, Qing,Wang, Congcong,Wu, Wenfa,Mao, Xu,Wang, Jiajia,Hu, Xiangdong
, p. 1208 - 1212 (2016)
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.
Organoytterbium ate complexes extend the value of cyclobutenediones as isoprene equivalents
Packard, Emma,Pascoe, David D.,Maddaluno, Jacques,Goncalves, Theo P.,Harrowven, David C.
, p. 13076 - 13079 (2014/01/06)
Changing course: While organolithium and Grignard reagents favor addition to C1 of A (R=Me), the corresponding organoytterbium reagents add to C2 (R=tBu). Computational studies provide insights into the nature of organoytterbium species and their reactivity, and a total synthesis of (-)-mansonone B illustrates the utility of the method in terpenoid synthesis. Tf=trifluoromethanesulfonyl.
Generation of 1,2-bisketenes from cyclobutene-1,2-diones by flash photolysis and ring closure kinetics
Allen, Annette D.,Colomvakos, Jim D.,Diederich, Fran?ois,Egle, Ian,Hao, Xiaokuai,Liu, Ronghua,Lusztyk, Janusz,Ma, Jihai,McAllister, Michael A.,Rubin, Yves,Sung, Kuangsen,Tidwell, Thomas T.,Wagner, Brian D.
, p. 12125 - 12130 (2007/10/03)
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.
An Improved Method for the Synthesis of Substituted Cyclobutenediones
Liebeskind, Lanny S.,Fengl, Richard W.,Wirtz, Kevin R.,Shawe, Thomas T.
, p. 2482 - 2488 (2007/10/02)
Practical and high yielding routes to substituted cyclobutenediones are described. 3,4-Bis(1-methylethoxy)cyclobut-3-ene-1,2-dione (diisopropyl squarate), a stable, crystalline derivative of squaric acid, was easily prepared by refluxing squaric acid in 2
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.
A SIMPLE SYNTHESIS OF SOME CYCLIC AND ACYCLIC CYCLOBUTENEDIONES
Liebeskind, Lanny S.,Baysdon, Sherrol L.
, p. 1747 - 1750 (2007/10/02)
Cyclobutenediones can be prepared from cyclic and acyclic ketones by a simple four step procedure.
