Zinc(ii)-mediated generation of 5-amino substituted 2,3-dihydro-1,2,4-oxadiazoles and their further Zn^II-catalyzed and O₂-involving transformations

Abstract

ZnII-activated cyanamides NCNR2 react with the acyclic N-alkyl ketonitrones Ph2CN+(O−)R′ achieving uncomplexed 2,3-dihydro-1,2,4-oxadiazoles.

Copper(I)-Catalyzed 1,3-Dipolar Cycloaddition of Ketonitrones to Dialkylcyanamides: A Step toward Sustainable Generation of 2,3-Dihydro-1,2,4-oxadiazoles

“…Heterocycles 1 – 3 , 5 , and 7 were identified by comparison of their 1 H NMR and high-resolution ESI + -MS spectra with those known from the literature. 10 New heterocycles 6 , 8 – 16 were characterized by elemental analyses (C, H, N), HRESI + -MS, 1 H and 13 C{ 1 H} NMR, Fourier transform infrared (FTIR), and also by X-ray diffraction (for 9 , 12 , and 16 ). Heterocycle 4 was not isolated from the reaction mixture due to low yield and was identified by HRESI + -MS in the reaction mixtures ( m / z : 386.2246 [M + H] + , calcd 386.2227).…”

“…Bond distances and angles for these structures are close to those in the previously reported structures of DHODs (Table S2). 10…”

“…Recently, we have demonstrated (F) that disubstituted cyanamides, NCNRR′, being coordinated to a Zn II center, can be employed in the CA with acyclic N -alkyl ketonitrones Ph 2 CN + (O – )­R′ (R′ = Me, CH 2 Ph), and this reaction proceeds easily achieving the respective metal-free heterocycles . We succeeded in replacing platinum and palladium in the CA with more favorable zinc­(II), but the developed method employs stoichiometric rather than catalytic amounts of Zn­(OTf) 2 .…”

Solvent- and halide-free synthesis of pyridine-2-yl substituted ureas through facile C–H functionalization of pyridine N-oxides

“…60 Firstly, we tested several dialkylcyanamides, whose intriguing chemistry becomes increasingly popular in recent years. [61][62][63][64][65][66][67][68] In all cases, target ureas 4a-f were obtained in 73-92% yields (Scheme 3). Even for 4-morpholinecarbonitrile, urea 4f was isolated in 89% yield.…”

Cyclometalated Iridium(III) Complexes Featuring Disubstituted Cyanamides

“…Owing our interest in the luminescent platinum group metal complexes (for our works in this field see) and coordination chemistry of cyanamides (for recent works see,, , ), we report herein the generation of a novel family of mono‐ and bis (dialkylcyanamide) cyclometalated iridium(III) complexes, viz. [IrCl(ppy) 2 (NCNR 2 )] and [IrCl(ppy) 2 (NCNR 2 ) 2 ](OTf) (ppy is 2‐phenylpyridinato‐ C 2 , N , OTf is CF 3 SO 3 ), and study of their photoluminescence in the solid state.…”