Osmium-Promoted σ-Bond Activation Reactions on Nucleosides

Abstract

OsH6(PiPr3)2 has been used to selectively activate C–H, O–H, and C–C sigma bonds in nucleobases and nucleosides, including derivatives of 6-phenylpurine and 4-phenylpyrimidine, leading to cyclometalated mononuclear Os–trihydride complexes, in excellent yields and as single products. Additionally, OsH6(PiPr3)2 promotes the efficient dehydrogenative decarbonylation of primary alcohols in nucleosides having unprotected sugar moieties. The incorporation of OsH2Cl2(PiPr3)2 in the structure of cyclometalated Ir­(III) and Rh­(III) half-sandwich complexes derived from nucleosides allows the preparation of a class of heterobimetallic bioorganometallic complexes having at least one M–C bond. These methodologies could be used in the future as a way for the orthogonal functionalization of oligonucleotides.

Phosphorescent Ir(iii) complexes derived from purine nucleobases

“…8 Such methodologies involve the use of 6-phenyl purine and 4-phenyl pyrimidine derivatives in N-directed C sp2 –H 16 and C sp3 –H 17 bond activation, alkyne insertion 18 and dehydrogenative decarbonylation reactions. 19 Our results successfully demonstrate that it is possible to carry out classical organometallic reactions on these challenging, highly functionalized and sensitive substrates.…”

Alternative Conceptual Approach to the Design of Bifunctional Catalysts: An Osmium Germylene System for the Dehydrogenation of Formic Acid

“…In spite of it being argued as the reason for the degradation of some hydrogenation catalysts 28 and of being known for the rupture of P–C bonds of some quaternary phosphonium salts under catalytic conditions, 29 the hydrogenolysis of P–C bonds is a slightly common reaction. It should be furthermore mentioned that, although complex 1 has shown a notable ability to activate σ-bonds, 30 including C–C, 31 C–N, 32 and C–O 33 among others, it had never participated in the rupture of a C–P bond.…”

Cyclometalated Osmium Compounds and beyond: Synthesis, Properties, Applications

“…Cyclometalated complexes 232 – 235 were obtained in good yields ( Figure 58 ). The authors mentioned that this methodology could be applied to the functionalization of oligonucleotides with promising potential biological applications [ 149 ].…”