5'-O-(2-Isopropoxyprop-2-yl)-protected Phosphoramidite Building Blocks in the Liquid Phase Oligonucleotide Synthesis

5'-O-(2-isopropoxyprop-2-yl) (IIP)-protection was introduced to 5’-OH function of nucleosides in high yields by an acid-catalysed transacetalization with 2,2-diisopropoxypropane. The applicability of this temporal 5’-O-protecting group was demonstrated in the liquid phase oligonucleotide synthesis (LPOS) using the corresponding phosphoramidite building blocks (dA, dG, dC and dT) and a tetrapodal precipitative soluble support. Standard protecting groups were used on nucleobases. Tetrazole as an activator, followed by oxidation using m-chloroperbenzoic acid, was used for the coupling. The IIP was shown to be a capable choice to the 5’-O protection in solution phase synthesis. It could be readily removed with formic acid (t_1/2<10 s in 6 % HCOOH in dichloromethane/methanol (2/1) at RT), resulting in volatile byproducts (acetone and isopropanol).     

Ruthenium-Assisted Tellurium Abstraction in Bis(thiophen-2-yl) Ditelluride

The reaction of [RuCl₂(CO)₃]₂ and Te₂Tpn₂ (Tpn=thiophen-2-yl, C₄H₃S) in the absence of light resulted in the formation of cct-[RuCl₂(CO)₂(TeTpn₂)₂] ( 1 ) [cis(Cl)-cis(CO)-trans(TeTpn₂)] and TeTpn₂ ( 2 ) together with the precipitation of tellurium. The complex 1 and the monotelluride 2 were characterized by NMR spectroscopy and single-crystal X-ray diffraction. The decomposition of Te₂Tpn₂ to TeTpn₂ has been monitored by ¹²⁵Te NMR spectroscopy and seemed to be faster than the ligand substitution in [RuCl₂(CO)₃]₂ by TeTpn₂. A catalytic cycle is proposed for the decomposition of Te₂Tpn₂ to TeTpn₂ based on the PBE0-D3/def2-TZVP calculations.     

ChemInform Abstract: Icosahedral Au72: A Predicted Chiral and Spherically Aromatic Golden Fullerene

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