1760-46-9Relevant academic research and scientific papers
PPh3/Selectfluor-Mediated Transformation of Carboxylic Acids into Acid Anhydrides and Acyl Fluorides and Its Application in Amide and Ester Synthesis
Yang, Zhen,Chen, Siwei,Yang, Fang,Zhang, Chenxi,Dou, You,Zhou, Qiuju,Yan, Yizhe,Tang, Lin
, p. 5998 - 6002 (2019/08/21)
By taking the advantage of PPh3/Selectfluor system, carboxylic acids are efficiently converted into the pivotal intermediates acyloxyphosphonium ions that can selectively react with a second carboxylic acid or fluoride to in situ yield the corresponding acid anhydrides or acyl fluorides. The developed protocol features commercially availabile reagents, no involvement of base, room temperature conditions, and simple experimental procedure. Additionally, various amides or esters are readily achieved, respectively, with the addition of amines or alcohols.
Isothiourea-Catalysed Regioselective Acylative Kinetic Resolution of Axially Chiral Biaryl Diols
Qu, Shen,Greenhalgh, Mark D.,Smith, Andrew D.
supporting information, p. 2816 - 2823 (2019/02/05)
An operationally simple isothiourea-catalysed acylative kinetic resolution of unprotected 1,1′-biaryl-2,2′-diol derivatives has been developed to allow access to axially chiral compounds in highly enantioenriched form (s values up to 190). Investigation of the reaction scope and limitations provided three key observations: i) the diol motif of the substrate was essential for good conversion and high s values; ii) the use of an α,α-disubstituted mixed anhydride (2,2-diphenylacetic pivalic anhydride) was critical to minimize diacylation and give high selectivity; iii) the presence of substituents in the 3,3′-positions of the diol hindered effective acylation. This final observation was exploited for the highly regioselective acylative kinetic resolution of unsymmetrical biaryl diol substrates bearing a single 3-substituent. Based on the key observations identified, acylation transition state models have been proposed to explain the atropselectivity of this kinetic resolution.
Facile and direct synthesis of symmetrical acid anhydrides using a newly prepared powerful and efficient mixed reagent
Rouhi-Saadabad, Hamed,Akhlaghinia, Batool
, p. 479 - 485 (2015/01/30)
An efficient mixed reagent for direct synthesis of symmetrical carboxylic anhydrides from carboxylic acids has been prepared. Carboxylic acids are converted to anhydrides using triphenylphosphine/ trichloroisocyanuric acid under mild reaction conditions at room temperature. Short reaction time, excellent yields of products, low cost, availability of reagents, simple experimental procedure, and easy work-up of the products are the main advantages of the presented method.
A convenient method for the kinetic resolution of racemic 2-hydroxyalkanoates using diphenylacetic anhydride (DPHAA) and a chiral acyl-transfer catalyst
Nakata, Kenya,Sekiguchi, Akihiro,Shiina, Isamu
scheme or table, p. 1610 - 1619 (2012/01/03)
Diphenylacetic anhydride (DPHAA) was found to be a useful reagent for the kinetic resolution of racemic 2-hydroxyalkanoates in the presence of a catalytic amount of (R)-benzotetramisole ((R)-BTM). The combined use of DPHAA and (R)-BTM effectively produced a variety of the optically active 2-hydroxyalkanoates and the corresponding 2-acyloxyalkanoates from racemic 2-hydroxyalkanoates (s-values = 42-177). A fairly broad substrate scope was demonstrated by this novel chiral induction system. We also revealed that the use of only 0.3 equiv of DPHAA is enough to provide the optically active 2-acyloxyalkanoates in good yields and with excellent ee's by the added use of 0.3 equiv of pivalic anhydride for the kinetic resolution of the racemic 2-hydroxyalkanoates. Copyright
Selective esterifications of alcohols and phenols through carbodiimide couplings
Shelkov, Rimma,Nahmany, Moshe,Melman, Artem
, p. 397 - 401 (2007/10/03)
Esterification of carboxylic acids capable of forming ketene intermediates upon treatment with carbodiimides permits the selective acylation of alcohols in the presence of phenols lacking strong electron-withdrawing groups. The selectivity of acylations involving highly acidic phenols could be reversed through the addition of catalytic amount of acid. Esterification of other carboxylic acids was found to proceed through the formation of symmetric anhydrides and provide the opposite chemoselectivity. In both cases the relative acylation rates of substituted phenols are consistent with a reaction mechanism involving an attack of phenolate anions on electrophilic intermediates such as ketenes and symmetric anhydrides, with the carbodiimides serving both as an activating reagent and as a basic catalyst.
2-Chloro-1,3-dimethylimidazolinium chloride. 1. A powerful dehydrating equivalent to DCC
Isobe, Toshio,Ishikawa, Tsutomu
, p. 6984 - 6988 (2007/10/03)
2-Chloro-1,3-dimethylimidazolinium chloride (DMC) (3) can act as a powerful dehydrating agent, replacing DCC (1) under nearly neutral conditions. Its application to acylation and dehydration is described.
New synthetic technology for the synthesis of hindered α-diazoketones via acyl mesylates
Nicolaou,Baran, Phil S.,Zhong, Yong-Li,Choi, Ha-Soon,Fong, Kin Chiu,He, Yun,Yoon, Won Hyung
, p. 883 - 886 (2008/02/09)
(equation presented) A mild and reliable one-pot protocol for the elaboration of sterically demanding carboxylic acids into α-diazoketones via acyl mesylates has been developed. Aside from delineating the reaction parameters which render this strategy quite general for hindered carboxylic acids, we have directly proven the existence of the fleeting acyl mesylate group as the reactive species in these reactions and shed light onto the differing mechanisms which are operative in the activation of hindered and simple carboxylic acids with methanesulfonyl chloride.
The Effect of Pressure on the 4> Cycloaddition of Diphenylketen to Enol Ethers
Swieton, Gernot,Jouanne, Joern von,Kelm, Hartwig,Huisgen, Rolf
, p. 37 - 44 (2007/10/02)
The volume profiles for the cycloaddition reactions between diphenylketen and butyl vinyl ether, 2-methoxypropene, and 2,3-dihydro-4H-pyran, respectively, have been determined.For the first example a wide range of solvents was studied.The Kirkwood theory seems to be not fully adequate for the description of the solvent effects found for the rate konstant and especially for the partial molar volumes.Solvent cohesive energy densities offer an alternative description.In the most solvents the volumes of activation are similar in magnitude and support a concerted mechanism for the cycloaddition.
A convenient synthesis of 2'-O-acetal-N2-acyl derivatives of riboguanosine
Verdegaal, C. H. M.,Jansse, P. L.,Rooij, J. F. M. de,Veeneman, G.,Boom, J. H. van
, p. 200 - 204 (2007/10/02)
The partially protected and crystalline 2'-O-levulinoyl-3',5'-O-(tetraisopropyldisiloxane-1,3-diyl)guanosine derivative (4) serves as a key intermediate for the synthesis of 2'-O-acetal-N2-acylriboguanosines 1c.Acylation of 4 with diphenylaceti
