<p>The masked Ti(II) synthon (<sup>Ket</sup>guan)(<i>η</i><sup>6</sup>-Im<sup>Dipp</sup>N)Ti (<b>1</b>) oxidatively adds across thiophene to give ring-opened (<sup>Ket</sup>guan)(Im<sup>Dipp</sup>N)Ti[<i>κ</i><sup>2</sup>-<i>S</i>(CH)<sub>3</sub><i>C</i>H] (<b>2</b>). Complex <b>2</b> is photosensitive, and upon exposure to light, reductively eliminates thiophene to regenerate <b>1</b> – a rare example of early-metal mediated oxidative-addition/reductive-elimination chemistry. DFT calculations indicate strong titanium π-backdonation to the thiophene π*-orbitals leads to the observed thiophene ring opening across titanium, while a proposed photoinduced LMCT promotes the reverse thiophene elimination from <b>2</b>. Finally, pressurizing solutions of <b>2 </b>with H<sub>2</sub> (150 psi) at 80 °C leads to the hydrodesulfurization of thiophene to give the Ti(IV) sulfide (<sup>Ket</sup>guan)(Im<sup>Dipp</sup>N)Ti(S) (<b>3</b>) and butane. </p>
<p>We report a
Ni(0)-catalyzed cross coupling reaction between simple ketones and 1,3-dienes. A
variety of a-allylic
alkylation products were formed in an 1,2-addition manner with excellent regioselectivity.
Water was found to significantly accelerate this transformation. A HO-Ni-H
species generated from oxidative addition of Ni(0) to H<sub>2</sub>O is
proposed to play a “dual role” in activating both the ketone and the diene
substrate.</p>
<p>7-methylguanosine, the so-called mRNA cap 0 bears a very labile C8-H
bond, due to the formation of an ylide/N-heterocyclic carbene, upon proton
loss. The reaction of 7-methylguanosine
with Pt(PPh3)4, via C-H
oxidative addition, yields a hydrido–PtII carbene complex and this reactivity
can be extrapolated to 7,9-dimethylguanine. </p>
Oxidative addition of the P‒P single bond of an ortho-carborane-derived 1,2-diphosphetane (1,2-C2(PMes)2B10H10) (Mes = 2,4,6-Me3C6H2) to cobalt(-I) and nickel(0) sources affords the first heteroleptic complexes of a carborane-bridged bis(phosphanido) ligand....
This work uses DFT calculations to explore Pd(ii)-catalysed iodine(iii)-mediated alkoxylation of unactivated C(sp3)–H bonds and reveals how important the isomerization is in triggering the oxidative addition of ArIX2 to Pd(ii).