Synthesis and Reactivity of NNNNN-Pincer Multidentate Pyrrolyl Rare-Earth-Metal Amido-Chloride or Dialkyl Complexes
The NNNNN-pincer multidentate pyrrolyl rare-earth-metal amido-chloride complexes {η1:κ3-2,5-[CH3N(CH2CH2)2NCH2]2C4H2N}RECl[N(SiMe3)2] (RE = Y (2a), Sm (2b), Dy (2c), Er (2d), Yb (2e)) were synthesized by one step from reactions of [(Me3Si)2N]3RE(μ-Cl)Li(T
Ph3P/I2-mediated synthesis of N,N′,N″-substituted guanidines and 2-iminoimidazolin-4-ones from aryl isothiocyanates
A convenient one-pot procedure for the synthesis of acyclic and cyclic guanidines mediated by the Ph3P/I2 system is described. Sequential condensation of aryl isothiocyanates with amines followed by dehydrosulfurization and guanylation could lead to both symmetric and unsymmetric N,N′,N″-substituted derivatives. Through a tandem guanylation-cyclization, a series of 2-iminoimidazolin-4-ones could also be prepared in good yields from the reaction of aryl isothiocyanates with amino acid methyl esters.
Wangngae, Sirilak,Pattarawarapan, Mookda,Phakhodee, Wong
p. 10331 - 10340
(2018/05/31)
One-Pot Synthesis of C2 Symmetric and Asymmetric N,N′,N″-Substituted Guanidines from Aryl Isothiocyanates and Amines
Highly substituted guanidines were conveniently prepared through a one-pot reaction between aryl isothiocyanates and amines mediated by the Ph3P-I2/Et3N system. The C 2-symmetric N,N′,N″-substituted guanidines were readily accessed using a 1:2 molar ratio of an aryl isothiocyanate and an amine; while sequential addition of two different amines in equimolar ratios gave rise to asymmetric derivatives. Both primary and secondary amines were found to react preferentially with electron-deficient aryl isothiocyanates, rapidly providing guanidines in good yields under mild conditions.
Wangngae, Sirilak,Pattarawarapan, Mookda,Phakhodee, Wong
p. 1121 - 1127
(2016/05/19)
Desulfurization strategy in the construction of azoles possessing additional nitrogen, oxygen or sulfur using a copper(I) catalyst
A tandem and convergent approach to various N-, O-, or S-containing azoles has been developed by exploiting the thiophilic property of copper( I) iodide used in a catalytic quantity. The present protocol gives access to amino-substituted tetrazoles, triazoles, oxadiazoles and thiadiazoles via oxidative desulfurization of their respective precursors followed by inter- or intramolecular attack of suitable nucleophiles. For aminotetrazoles and triazoles an excellent regioselectivity has been achieved through proper tuning of the pKa values of the parent amines attached to unsymmetrical thioureas. The method represents an autocatalytic process in which copper( I) iodide gets converted to copper(II) sulfide which in turn transforms to active copper(II) oxide that effectively carries forward the catalytic cycle. The fate of the copper catalyst has also been studied using scanning electron microscopic (SEM) and energy-dispersive X-ray spectroscopic (EDS) analyses which give an insight into the mechanism for this catalytic process.
Guin, Srimanta,Rout, Saroj Kumar,Gogoi, Anupal,Nandi, Shyamapada,Ghara, Krishna Kanta,Patel, Bhisma K.
p. 2757 - 2770
(2013/01/15)
The synthesis of some new sulfur-bearing various heterocyclic systems derived from asymmetrical N,N′-disubstituted thiourea derivatives
The heterocyclization of an asymmetrical N,N′-disubstituted thiourea (1a-d) in ring closure reactions with Br2/AcOH, ethyl chloroacetate, diethyl oxalate, diethyl malonate, and hydrazine hydrate led to the direct formation of sulfur-bearing var
Saad, Hosam
p. 1557 - 1567
(2007/10/03)
Carbodiimide metathesis catalyzed by vanadium oxo and imido complexes via imido transfer