4490-75-9Relevant articles and documents
KINETIC STUDY OF THE FORMATION AND RUPTURE OF STABLE TETRAHEDRAL INTERMEDIATES. C-O, C-N and C-S BOND FORMATION
Nunez, Oswaldo,Rodriguez, Jose,Angulo, Larry
, p. 80 - 89 (1994)
Measured pseudo-first-order rate constants for intramolecular formation of tetrahedral intermediates from N-2-hydroxyethylphthalimide, N-2-aminoethylphthalimide and N-2-thioethylphthalimide at pH > 6 are reported.The reaction is specific and general base catalysed, with β(Bronsted) values 0.44, 0.52 and 0.52 respectively.From a plot of log kb (general base rate constants) vs γ' , β'nuc values of 0.01 (with OH- as specific base), 0.25 (with imidazole as general base) and 0.27 (with HPO42- as general base were obtained).The observed relationships pxy = υβ'nuc/ - υpKa = - υβ(Bronsted)/υγ' = 0.03 is supported by the predictions of an energy contour diagram, which, on extrapolation to a non-stable tetrahedral intermediate, predicts a late and slightly protonated transition state for the cleavage process.At pH 0.3 and α 0.1.A fast equilibrium between the intermediate and its N-protonated (amide) form is reached.The general base rupture of the latter is faster than that of the corresponding non-protonated intermediate by a factor of ca 1E9 - 1E10-fold.
Phenyliodine(III) Diacetate/I2-Mediated Domino Approach for Pyrrolo[1,4]Thiazines and 1,4-Thiazines by a One-Pot Morin Rearrangement of N,S-Acetals
Danton, Fanny,Othman, Mohamed,Lawson, Ata Martin,Moncol, Ján,Ghinet, Alina,Rigo, Beno?t,Da?ch, Adam
supporting information, p. 6113 - 6118 (2019/04/17)
An efficient domino transformation using a phenyliodine(III) diacetate (PIDA)/I2 combination towards Morin 1,4-thiazine compounds has been developed starting from N,S-acetals. The latter leads to “one-step” regioselective methylene insertion without the need for traditional sulfoxide intermediates in good yields. The reaction involves easily accessible N,S-acetals obtained from cost-effective basic ketones and cysteamine as starting materials. This process ultimately leads to 1,4-thiazines related to natural product and fused derivatives necessary for further QSAR study.
Multimetallic iridium-tin (Ir-Sn3) catalyst in N-acyliminium ion chemistry: Synthesis of 3-substituted isoindolinones via intra- and intermolecular amidoalkylation reaction
Maity, Arnab Kumar,Roy, Sujit
, p. 2627 - 2642 (2014/09/30)
The multimetallic iridium-tritin (Ir-Sn3) complex [Cp*Ir(SnCl3)2{SnCl2(H2O) 2}] (1) proved to be a highly effective catalyst towards C-OH bond activation of γ-hydroxylactams, leading to a nucleophilic substitution reaction known as the α-amidoalkylation reaction. Catalyst 1 can be easily synthesized from the reaction of (pentamethylcyclocyclopentadienyl)iridium dichloride dimer {[Cp*IrCl2]2} and tin(II) dichloride (SnCl2). In terms of catalyst loading, reaction conditions and yields of the product formed, 1 is found to be superior compared to classical Lewis acid catalysts. Different carbon (arenes, heteroarenes, allyltrimethylsilane, 1,3-dicarbonyls) and heteroatom (alcohols, thiols, amides and sulfonamides) nucleophiles have been successfully employed in the intramolecular and intermolecular alkylations, as well as in heterocyclization reactions. In the majority of cases good to excellent yields of 3-substituted isoindolinones and 5-substituted pyrrolidin-2-ones have been obtained. Besides, the reactions are also atom economical and salt free. It is proposed that the multimetallic Ir-Sn3 catalyst behaves as a mild and selective Lewis acid to activate the γ-hydroxylactam towards the formation of the N-acyliminium ion; the latter being trapped by potent nucleophiles leading to the desired products.