105398-69-4Relevant academic research and scientific papers
Synthesis of (-)-ilimaquinone via a radical decarboxylation and quinone addition reaction.
Ling, Taotao,Poupon, Erwan,Rueden, Erik J,Theodorakis, Emmanuel A
, p. 819 - 822 (2007/10/03)
[reaction: see text] A stereoselective synthesis of (-)-ilimaquinone (4) is presented. The synthetic strategy is based on a novel radical decarboxylation and quinone addition methodology that produces quinone 7 from reaction of thiohydroxamic acid derivat
Unified synthesis of quinone sesquiterpenes based on a radical decarboxylation and quinone addition reaction
Ling, Taotao,Poupon, Erwan,Rueden, Erik J.,Kim, Sun H.,Theodorakis, Emmanuel A.
, p. 12261 - 12267 (2007/10/03)
A unified synthesis of several quinone sesquiterpenes is described herein. Essential to this strategy is a novel radical addition reaction that permits the attachment of a fully substituted bicyclic core 16 to a variably substituted quinone 10. The addition product 15 can be further functionalized, giving access to natural products with a high degree of oxygenation at the quinone unit. The quinone addition reaction is characterized by excellent chemoselectivity, taking place only at conjugated and unsubstituted double bonds, and regioselectivity, being strongly influenced by the resonance effect of heteroatoms located on the quinone ring. These features were successfully applied to the synthesis of avarol (1), avarone (2), methoxyavarones (4, 5), ilimaquinone (6), and smenospongidine (7), thereby demonstating the synthetic value of this new method.
The invention of radical reactions. Part 39. The reaction of white phosphorus with carbon-centered radicals. An improved procedure for the synthesis of phosphonic acids and further mechanistic insights
Barton, Derek H. R.,Vonder Embse, Richard A.
, p. 12475 - 12496 (2007/10/03)
White phosphorus in tetrahydrofuran under argon reacts in a long radical chain reaction with carbon radicals derived from Barton PTOC esters. The reaction is initiated by traces of oxygen and strongly inhibited by TEMPO. From the duration of the induction period the chain length can be measured as approximately one million. Each P4 molecule can add up to two carbon radicals. Oxidation of the adducts provides a convenient synthesis of phosphonic acids in high yield. With H2O2 at 0°C oxidation to the appropriate phosphinic acids is fast. For sensitive natural products the further transformation to phosphonic acids is best carried out at room temperature with an excess of SO2. In this way even linoleic acid can be convened to the corresponding phosphonic acid in good yield without any attack on the skipped diene unit. TEMPO is also remarkable for its stabilization of white phosphorus in solution when exposed to oxygen. Likewise an ordinary phosphine, like tributyl phosphine, is also stabilized by small amounts of TEMPO.
N-hydroxypyridine-2(1H)-thione derivatives of carboxylic acids as activated esters. Part II. Applications in peptide synthesis
Barton, Derek H. R.,Ferreira, J. Albert
, p. 9367 - 9386 (2007/10/03)
The N-hydroxypyridine-2(1H)-thione derivatives of two urethane-protected α-amino acids readily reacted with the α-amino acid esters or the corresponding benzenesulfenamides to give simple dipeptides in reasonable yields. The benzenesulfenamides are the re
The invention of radical reactions. Part XXXVII. A convenient radical synthesis of dialkyl diselenides from carboxylic acids
Barton, Derek H. R.,Fontana, Giovanni
, p. 11163 - 11176 (2007/10/03)
A new and convenient synthesis of dialkyl diselenides from carboxylic acids by Barton PTOC ester based radical chemistry is described. This method was especially successful when O-cholestan-3β-yl-2,2,2-trichloroselenoacetate and O-neopentyl selenobenzoate
N-hydroxypyridine-2(1H)-thione derivatives of carboxylic acids as activated esters. Part I. The synthesis of carboxamides
Barton, Derek H. R.,Ferreira, J. Albert
, p. 9347 - 9366 (2007/10/03)
The reaction between an acyl derivative of N-hydroxypyridine-2(1H)- thione (a Barton PTOC ester) and either an amine (primary or secondary), or the corresponding sulfenamide, led to the formation of a carboxamide in a clean transformation requiring minimal work-up and purification. The reaction with a sulfenamide is particularly useful since the only by-product, an unsymmetrical disulfide, is of both synthetic and biological value. In sterically demanding cases, Barton PTOC esters were more reactive towards benzenesulfenamides than to the corresponding free amines.
The Invention of Radical Reactions. XXXIII Homologation Reactions of Carboxylic Acids by Radical Chain Chemistry
Barton, Derek H. R.,Chern, Ching-Yuh,Jaszberenyi, Joseph Cs.
, p. 407 - 426 (2007/10/02)
Various carbon radicals can be generated from carboxylic acids via the corresponding Barton esters.These radicals can be used for the synthesis of longer chain homologues of the original acids.
A facile preparation method for α,α-difluoroalkanecarboxylic acids and esters. A formal difluoromethylene insertion to alkanecarboxylic acids using radical reaction
Okano, Takashi,Takakura, Nobuyuki,Nakano, Yuko,Okajima, Asako,Eguchi, Shoji
, p. 1903 - 1920 (2007/10/02)
Various alkyl radicals generated by the photoreaction of a series of Barton esters reacted with 1,1-dichloro-2,2-difluoroethene to give radical adducts as the major product accompanied with self-trapping products. Primary, secondary, tertiary, benzyl, and some unsaturated alkyl radicals as well as those with another functional group such as ether, carbonyl, and azide were applicable. Barton esters of diacids also afford 1:2 adducts with a small amount of 1:1 adducts and bis-self-trapping products except for the succinic case. These adducts were hydrolyzed with AgNO3/H2O-THF to α,α-difluoroalkanecarboxylic acids and methanolyzed with AgNO3/MeOH to the corresponding methyl esters. 4-Azido-2,2-difluorobutylic acid and the methyl ester were converted to difluoro-GABA and difluoro-γ-lactams.
Use of 2,3-Bis(phenylsulfonyl)-1-propene as a Multicoupling Reagent
Padwa, Albert,Kline, Donald N.,Murphree, S. Shaun,Yeske, Philip E.
, p. 298 - 306 (2007/10/02)
2,3-Bis(phenylsulfonyl)-1-propene (1) reacts with various amines to afford products derived from addition across the double bond as well as SN2' displacement.When treated with 2-piperidinemethanol, bissulfone 1 gave the expected SN2'
The invention of radical reactions. Part XXV. A convenient method for the synthesis of the acyl derivatives of N-hydroxypyridine-2-thione
Barton,Samadi
, p. 7083 - 7090 (2007/10/02)
Treatment of the readily available di-N-oxide - of 2-thiopyridine disulfide 6 with tributylphosphine in the presence of a carboxylic acid provides a convenient and high yielding synthesis of the acyl derivatives 2 of N-hydroxy-2-thio-pyridone. Application of this procedure to the acids 17 and 18 gave, after irradiation in the presence of t-butylthill, the desired decarboxylated derivatives in high (>90%) yield.
