1354485-46-3Relevant academic research and scientific papers
Facile and reversible 1,3-dipolar cycloaddition of aryl ketonitrones to platinum(ii)-bound nitriles: Synthetic, structural, and theoretical studies
Kritchenkov, Andreii S.,Bokach, Nadezhda A.,Kuznetsov, Maxim L.,Dolgushin, Fedor M.,Tung, Tran Q.,Molchanov, Alexander P.,Kukushkin, Vadim Yu
, p. 687 - 699 (2012/04/04)
The reaction between trans-[PtCl2(NCR) 2] (R = Et 1, NMe2 2, NEt2 3, NC5H10 4) and the acyclic triaryl ketonitrones Ph2C=N(O)C6H4R-p (R = H 5, Me 6, Cl 7, OMe 8) proceeds as a facile and consecutive two-step intermolecular cycloaddition to give the mono-cycloaddition products trans-[PtCl2(NCR){Na= C(R)ON(C6H4R-p)CbPh2}](ab) (R/R = Et/H 9, Et/Me 10, Et/Cl 11, Et/OMe 12, NMe2/H 13, NMe2/Me 14, NMe2/Cl 15, NMe2/OMe 16, NEt2/H 17, NEt2/Me 18, NEt2/Cl 19, NEt2/OMe 20, NC 5H10/H 21, NC5H10/Me 22, NC5H10/Cl 23, NC5H10/OMe 24) and then the bis-2,3-dihydro-1,2,4- oxadiazole complexes trans- [PtCl2{Na=C(R)ON(C6H4R-p)CbPh2}2](ab) (R/R = Et/H 25, Et/Me 26, Et/Cl 27, Et/OMe 28, NMe2/H 29, NMe2/Me 30, NMe2/Cl 31, NMe 2/OMe 32, NEt2/H 33, NEt2/Me 34, NEt2/Cl 35, NEt2/OMe 36, NC5H10/H 37, NC5H10/Me 38, NC5H10/Cl 39, NC5H10/OMe 40). The ketonitrones Ph2C=N(O)C6H4R-p were found to be unexpectedly much more reactive toward the platinum(II)-bound nitriles than the related aldonitrones p-RC6H4CH=N(O)R (R= Me, Ph; R = H, Me), and the difference in the reactivity in 1,3- dipolar cycloaddition (DCA) of the keto- and aldonitrones was interpreted by theoretical calculations and was explained in terms of the orbital arguments as a result of the increase of the HOMOnitrone energy from aldo- to ketonitrones. The first example of the reversibility in metal-mediated DCA of nitrones to nitriles was observed, and this phenomenon, as follows from the performed theoretical study, is justified by the thermodynamic instability of the PtII-bound 3,3-diaryl-2,3-dihydro-1,2,4- oxadiazoles. Metalfree C5-diphenyl-2,3-dihydro-1,2,4-oxadiazoles 42 and 43 were liberated from corresponding (oxadiazole)2PtII complexes 26 and 30 by treatment with excess NaCN, and these heterocycles were characterized by high-resolution ESI+-MS and 1H and 13C{1H} NMR spectroscopies.
