18764-68-6Relevant academic research and scientific papers
2-Picolylamino(diphenylphosphinoselenoic)amide supported zinc complexes: Efficient catalyst for insertion of N–H bond into carbodiimides, isocyanates, and isothiocyanate
Harinath, Adimulam,Bano, Kulsum,Ahmed, Shakil,Panda, Tarun K.
supporting information, p. 23 - 32 (2017/09/25)
We report here the hydroamination of heterocumulenes such as carbodiimides, isocyanates, and isothiocyanates by zinc complexes supported by the ligand 2-picolylamino-(diphenylphosphinoselenoic)amide [{(Ph2P-(?Se)}2NCH2(C5H4N)] (1). A series of zinc complexes [κ2-{(Ph2P-(?Se)}2NCH2(C5H4N)ZnX2] [(X?Cl (2), Br (3a), I (4)] were prepared from ligand 1 and the corresponding zinc dihalide in a 1:1 molar ratio at 60°C in a chloroform solvent. The reaction of ligand 1 and ZnBr2 in methanol yielded another zinc complex [κ2-{(Ph2P-(?Se)}2NCH2(C5H4N)ZnBr2(CH3OH)] (3b). The molecular structures of compounds 3a, 3b, and 4 were established through single-crystal X-ray diffraction analyses. The solid-state structures of all the complexes revealed a κ2- chelation through pyridine nitrogen and selenium atoms of ligand 1 to the zinc ion. Complex 2 proved to be a competent pre-catalyst for the addition of the amine N–H bond to carbodiimides, isocyanates, and isothiocyanates. The reaction scope was expanded to reactions of aliphatic and aromatic amines with phenylisocyanate and phenylisothiocyanate in toluene solvents, which proceeded rapidly at room temperature with 5 mol% catalyst loading to yield (up to 99%) the corresponding derivatives of urea and thio-urea. However, a temperature of 90°C was needed for the hydroamination of N,N′ dicyclohexylcarbodiimide. We also report the most plausible mechanism of the hydroamination reaction.
Highly Active Dinuclear Titanium(IV) Complexes for the Catalytic Formation of a Carbon-Heteroatom Bond
Bhattacharjee, Jayeeta,Harinath, Adimulam,Banerjee, Indrani,Nayek, Hari Pada,Panda, Tarun K.
supporting information, p. 12610 - 12623 (2018/10/09)
A series of mononuclear titanium(IV) complexes with the general composition κ3-[R{NHPh2P(X)}2Ti(NMe2)2] [R = C6H4, X = Se (3b); R = trans-C6H10, X = S (4a), Se (4b)] and [{κ2-N(PPh2Se)2}2Ti(NMe2)2] (6b) and two dinuclear titanium(IV) complexes, [C6H4{(NPh2PS)(N)}Ti(NMe2)]2 (3c) and [{κ2-N(PPh2Se)}Ti(NMe2)2]2 (6c), are reported. Dinuclear titanium(IV) complex 6c acts as an efficient catalyst for the chemoselective addition of an E-H bond (E = N, O, S, P, C) to heterocumulenes under mild conditions. The catalytic addition of aliphatic and aromatic amines, alcohol, thiol, phosphine oxide, and acetylene to the carbodiimides afforded the corresponding hydroelemented products in high yield at mild conditions with a broader substrate scope. The catalytic efficiency of the dinuclear complex depends on the cooperative effect of the TiIV ions, the systematic variation of the intermetallic distance, and the ligand's steric properties of the complex, which enhances the reaction rate. Most interestingly, this is the first example of catalytic insertion of various E-H bonds into the carbodiimides using a single-site catalyst because only the titanium-mediated insertion of E-H into a C-N unsaturated bond is reported to date. The amine and alcohol insertion reaction with the carbodiimides showed first-order kinetics with respect to the titanium(IV) catalyst as well as substrates. A most plausible mechanism for hydroelementation reaction is also proposed, based on the spectroscopic data of the controlled reaction, a time-course study, and the Hammett plot.
Hydroamination of carbodiimides, isocyanates, and isothiocyanates by a bis(phosphinoselenoic amide) supported titanium(IV) complex
Bhattacharjee, Jayeeta,Das, Suman,Kottalanka, Ravi K.,Panda, Tarun K.
supporting information, p. 17824 - 17832 (2016/11/18)
The hydroamination of heterocumulenes such as carbodiimides, isocyanates, and isothiocyanates by a bis(phosphinoselenoic amide) supported titanium(iv) complex as a precatalyst is reported here. The titanium(iv) complex [{Ph2P(Se)NCH2CH2NPPh2(Se)}Ti(NMe2)2] (1) was synthesised by the reaction of tetrakis-(dimethylamido)titanium(iv) [Ti(NMe2)4] with [{Ph2P(Se)NHCH2CH2NHPPh2(Se)}] in toluene at ambient temperature. Titanium complex 1 proved to be a competent pre-catalyst for the addition of an amine N-H bond to carbodiimides, isocyanates, and isothiocyanates. The reaction scope was expanded to reactions of aliphatic and aromatic amines with phenylisocyanates and phenylisothiocyanates in toluene solvents proceeding rapidly at room temperature with 5 mol% catalyst loadings to yield the corresponding urea and thio-urea derivatives up to 99%. However, ambient temperature was needed for hydroamination of 1,3-dicyclohexylcarbodiimide. The amine addition reactions with isocyanates showed first order kinetics with respect to catalyst 1 as well as substrates. The most plausible mechanism for the hydroamination reaction was established by isolating 1,1-dimethylphenyl urea as a side product.
Insertion of arynes into thioureas: A new amidine synthesis
Biswas, Kallolmay,Greaney, Michael F.
supporting information; experimental part, p. 4946 - 4949 (2011/11/06)
Arynes, generated from trimethylsilyl phenyltriflate precursors, have been found to react with thioureas via a formal π-insertion into the C=S bond. The reaction contrasts with that of ureas, which proceeds via benzyne σ-insertion into the C-N bond, and r
Structural requirement of phenylthiourea analogs for their inhibitory activity of melanogenesis and tyrosinase
Thanigaimalai, Pillaiyar,Lee, Ki-Cheul,Sharma, Vinay K.,Joo, Cheonik,Cho, Won-Jea,Roh, Eunmiri,Kim, Youngsoo,Jung, Sang-Hun
experimental part, p. 6824 - 6828 (2011/12/22)
Effect of a series of 1-phenylthioureas 1a-k and 1,3-disubstituted thioureas 2a-k were evaluated against melanin formation in melanoma B16 cell line and mushroom tyrosinase. Inhibitory activity of tyrosinase of 1-phenylthioureas 1a-k is parallel to their melanogenic inhibition. Thus, the melanogenic inhibition in melanoma B16 cells of 1-phenylthioureas could be the result of inhibition of tyrosinase. However, 1,3-diaryl or 1-phenyl-3- alkylthioureas, 2a-k, appears as melanogenic inhibitor without inhibition of tyrosinase. The molecular docking study of 1e and 2b to binding pocket of tyrosinase provided convincing explanation regarding the necessity of direct connection of planar phenyl to thiourea unit without N′-substitution of phenylthioureas 1 as tyrosinase inhibitor and 2 as non-tyrosinase inhibitor.
