Highly Stereoselective 1,3-Dipolar Cycloaddition of Nitrones to (Nitrile)₂Pt^IISpecies Furnishing Diastereomerically Pure 2,3-Dihydro-1,2,4-oxadiazole Ligands

Abstract

Diastereomerically pure platinum(II) complexes 4-9 bearing tetrahydro-5,8-methanocyclohexa-[3 0 ,2 0 :4,5][1,3]oxazolo[3,2-b][1,2,4]oxadiazole ligands were generated under mild conditions (CH 2 Cl 2 , 20-25°C, 24 h) by an intermolecular Pt II -mediated 1,3-dipolar cycloaddition between enantiomerically pure camphor-derived oxazoline-N-oxides and the coordinated nitriles in the complexes trans-[PtCl 2 (R 0 CN) 2 ] (R 0 = Et, Ph, NMe 2 ). These species were characterized by elemental analyses (C, H, N), high-resolution ESI þ -MS, IR, 1 H and 13 C NMR spectroscopies, and also X-ray diffraction (for 5, 7, 8 3 CHCl 3 , and 9 3 Me 2 CO). Free heterocycles 10-13 were liberated as single stereoisomers from the (2,3-dihydro-1,2,4-oxadiazole) 2 Pt II complexes (R = Et, Ph) by treatment with excess NaCN and were characterized by high-resolution ESI þ -MS and 1 H and 13 C NMR spectroscopies.

cis-Tetrachloridobis(1H-imidazole-κN3)platinum(IV)

“…(Ravera et al, 2011;Esmaeilbeig et al, 2011;Al-Shuneigat et al, 2010;Wheate et al, 2007;van Zutphen et al, 2006). Within the framework of our projects the focus is on the synthesis of platinum complexes with Nheterocyclic ligands (Bokach, Kuznetsov et al, 2011;Kritchenkov et al, 2011;Bokach, Balova et al, 2011;Tskhovrebov et al, 2009;Luzyanin et al, 2009;Bokach et al, 2009;Krämer et al, 2000;Fritsky et al, 2000), the title compound (I) was synthesized and characterized by single-crystal X-ray diffraction.…”

“…For applications of platinum species bearing N-bonded heterocycles, see: Ravera et al (2011); Esmaeilbeig et al (2011); Al-Shuneigat et al (2010); Wheate et al (2007); van Zutphen et al (2006); Fritsky et al (2000); . For the synthesis of platinum complexes with Nheterocyclic ligands, see: Bokach, Kuznetsov et al (2011); Kritchenkov et al (2011); Bokach, Balova et al (2011); Tskhovrebov et al (2009); Luzyanin et al (2009); Bokach et al (2009). For related structures, see: Khripun et al (2006Khripun et al ( , 2007; Korte et al (1981); Kuduk-Jaworska et al (1988); Bayon et al (1987); Yip et al (1993); Chen et al (2006); Gao et al (2004); Garcia et al (2000); Hao & Yu (2007); Huo et al (2004).…”

Azide Chemistry – An Inorganic Perspective, Part II[‡][3+2]‐Cycloaddition Reactions of Metal Azides and Related Systems

“…[82,91b,594] This included questions of regiospecifity and stereospecificity, [585] the influence of the oxidation state of the metal ion, the nature of the nitrone [585] and the nitrile [586] (even including dialkylcyanamide), [586a] the biological (cytotoxic) activity, [595f] as well as methods for the cleavage of the heterocycle from the metal. [82,594] The experiments were accompanied by extensive theoretical calculations.…”

Dichloridobis[3-(4-methoxyphenyl)-2-methyl-5-(piperidin-1-yl)-2,3-dihydro-1,2,4-oxadiazole-κN4]platinum(II)

“…For the synthesis of platinum complexes bearing 2,3dihydro-1,2,4-oxadiazole ligands, see: Kritchenkov et al (2011). For related structures, see: Bokach & Kukushkin (2006); Bokach et al (2011); Fritsky et al (2006); Penkova et al (2009). For standard bond lengths, see: Allen et al (1987).…”