1219-32-5Relevant articles and documents
" Mediator Methodology" for the Synthesis of Peptides in a Two-Polymeric System
Shai, Yechiel,Jacobson, Kenneth A.,Patchornik, Abraham
, p. 4249 - 4252 (1985)
Abstract: A novel methodology is described for a potential automated self-controlled synthesis of peptides.The method is based on transferring an N-protected amino acid from one insoluble polymer (donor) such as a polymeric o-nitrophenyl ester (a "bank" of active ester) to an insoluble polymer-bound amino acid (acceptor),with the aid of a soluble mediator molecule (shadchan)2 The method gives high yields of pure peptides by garanteeing stoichiomeric supply of the active ester and allowing self monitoring.When the polymer-bound (dimethylamino)pyridinium salts, the condensation reaction was expended to also include sulfonation and particularly phosphorylation reactions.
Aminolysis of S-4-nitrophenyl X-substituted thiobenzoates: Effect of nonleaving-group substituents on reactivity and mechanism
Im, Li-Ra,Jeon, Sang-Eun,Um, Ik-Hwan
body text, p. 1153 - 1157 (2011/11/12)
A kinetic study is reported for aminolysis of S-4-nitrophenyl X-substituted thiobenzoates 3a-g in 80 mol % H2O/20 mol % DMSO at 25.0 ± 0.1 °C. Thiol esters 3a-g are 7.8-47.6 fold more reactive than the corresponding oxygen esters (i.e., 4-nitrophenyl X-substituted benzoates 1a-g). Such reactivity order appears to be in accordance with the expectation that 4-nitrothiophenoxide in 3a-g is a better nucleofuge than 4-nitrophenoxide in 1a-g since the former is 2.64 pKa units less basic than the latter. Hammett plot for the reactions of 3a-g exhibit poor correlation coefficients (R2 = 0.977-0.986) with negative deviation by substrates possessing an electrondonating group (EDG), while the Yukawa-Tsuno plots result in excellent linear correlation (R2 = 0.995-0.997) with ? = 0.93-1.23 and r = 0.57-0.67, indicating that the negative deviation shown by substrates possessing an EDG is caused by ground-state stabilization through resonance interactions but not due to a change in ratedetermining step upon changing the nonleaving-group substituent X. The p value increases as the incoming amine becomes more basic and more reactive, indicating that the RSP is not operative in the current reactions.
An alternative approach towards the syntheses of thioethers and thioesters using CsF-Celite in acetonitrile
Shah, Syed Tasadaque Ali,Khan, Khalid Mohammed,Martinez Heinrich, Angelica,Voelter, Wolfgang
, p. 8281 - 8283 (2007/10/03)
It has been found that syntheses of thioethers and thioesters of aliphatic, aromatic and heterocyclic compounds, bearing thiol groups, can be accomplished with alkyl, acyl, benzyl or benzoyl halides in acetonitrile and cesium fluoride-Celite. In this manner, compounds like ethanethiol, 1-pentanethiol, thiophenol, 4-methoxythiophenol, 4-nitrothiophenol, and 2-mercaptobenzoxazole, 2-mercaptobenzothiazole, and 2-mercapto-2-thiazoline can be successfully alkylated, acylated, benzylated or benzoylated. This procedure is convenient, efficient and practical for the preparation of thioethers and thioesters.
