91541-28-5Relevant academic research and scientific papers
Catalytic Redox Chain Ring Opening of Lactones with Quinones to Synthesize Quinone-Containing Carboxylic Acids
Xu, Xiao-Long,Li, Zhi
supporting information, p. 5078 - 5081 (2019/09/03)
Catalytic ring opening of five- to eight-membered lactones with quinones is achieved through a redox chain mechanism. With low loading of a simple metal triflate Lewis acid catalyst and a chain initiator, C-H bonds of many quinones were efficiently functionalized with carboxylic acid-containing side chains. This method also features 100% atom economy and wide substrate scope. A novel route to the anti-asthma drug Seratrodast was developed. Mechanism study suggests that the redox chain reaction likely undergoes a carbocation intermediate.
Radical-chain addition of aldehydes to alkenes catalysed by thiols
Dang, Hai-Shan,Roberts, Brian P.
, p. 67 - 76 (2007/10/03)
Thiols catalyse the radical-chain addition of primary aliphatic aldehydes R1CH2CHO to terminal alkenes H2C=CR2R3 to give ketonic adducts R1CH2C(O)CH2C(H)R2R3 in moderate to good yields.The reaction takes place under mild conditions (dioxane solvent, 60 deg C) and is initiated by di-tert-butyl hyponitrite (TBHN).Thiol catalysis is effective for hydroacylation of electron-rich, -neutral and -deficient alkenes, but is most efficient for addition to electron-rich double bonds.For example, the addition of butanal (2 equiv.) to isopropenyl acetate in the presence of TBHN (2x2.5 molpercent) and methyl thioglycolate (MeO2CCH2SH; 2x5 molpercent) gives the adduct in 80percent yield, whilst a similar reaction in the absence of thiol catalyst affords only an 8percent yield.Other enol acetates, silyl enol ethers, an enol phosphate and butyl vinyl ether react similarly.For comparison, the reaction of butanoyl phenyl selenide with isopropenyl acetate, in the presence of tributyltin hydride and azoisobutyronitrile initiator in benzene at 80 deg C, gives the adduct in only 7percent yield.Methyl thioglycolate is generally the most efficient catalyst for hydroacylation of electron-rich alkenes, whilst tert-dodecanethiol is more effective for addition of aldehydes to electron-deficient alkenes.Triorganosilanethiols also function as catalysts, as does the arenethiol 2,4,6-tris(trifluoromethyl)thiophenol.The role of the thiol is to act as a polarity-reversal catalyst that promotes the overall hydrogen-atom transfer from the aldehyde to the carbon-centred radical produced by addition of the acyl radical to the alkene.Intramolecular hydroacylation is also subject to thiol catalysis and the radical-chain cyclisation of citronellal to a mixture of menthone and isomenthone is effectively promoted in the presence of triphenylsilanethiol.
Acyl Radicals: Intermolecular and Intramolecular Alkene Addition Reactions
Boger, Dale L.,Mathvink, Robert J.
, p. 1429 - 1443 (2007/10/02)
A full study of the use of phenyl selenoesters as precursors to acyl radicals and their subsequent participation in intermolecular and intramolecular alkene addition reactions is detailed.Primary alkyl-, vinyl-, and arylsubstituted acyl radicals generated by Bu3SnH treatment of the corresponding phenyl selenoesters participate cleanly in intermolecular addition reactions with alkenes bearing electron-withdrawing or radical-stabilizing substituents at rates that exceed those of the potentially competitive decarbonylation or reduction.Similarly, their intramolecular addition to activated or unactivated alkenes proceeds without significant competitive reduction or decarbonylation and at rates generally >/= 1 x 106 s-1 with some occuring at rates >/= 3 x 107 s-1.Consistent with their behavior in intermolecular addition reactions, the 5-exo-trig cyclizations of secondary and tertiary alkyl-substituted acyl radicals to an unactivated olefin acceptor may be accompanied by varying degrees of decarbonylation, even under low-temperature free-radical conditions.Studies are presented which suggest that the intramolecular additions of acyl radicals to alkenes under the conditions detailed herein may be regarded as irreversible, kinetically controlled processes which exhibit regioselectivity that is predictable based on well-established empirical rules set forth for the analogous free-radical cyclization reactions of alkyl radicals.
Phenyl Selenoesters as Effective Precursors of Acyl Radicals for Use in Intermolecular Alkene Addition Reactions
Boger, Dale L.,Mathvink, Robert J.
, p. 1777 - 1779 (2007/10/02)
The scope of the use of phenyl selenoesters as effective precursors to acyl radicals for use in intermolecular olefin addition reactions is detailed.
