Podophyllotoxin is probably the most prominent representative of lignan natural products. Deoxy‐, epi‐, and podophyllotoxin, which are all precursors to frequently used chemotherapeutic agents, were prepared by a stereodivergent biotransformation and a biocatalytic kinetic resolution of the corresponding dibenzylbutyrolactones with the same 2‐oxoglutarate‐dependent dioxygenase. The reaction can be conducted on 2 g scale, and the enzyme allows tailoring of the initial, “natural” structure and thus transforms various non‐natural derivatives. Depending on the substitution pattern, the enzyme performs an oxidative C−C bond formation by C−H activation or hydroxylation at the benzylic position prone to ring closure.

Direct, one-pot oxidation of benzyl alcohols to benzoic acid with H ₂ O ₂ catalyzed by Fe( iii ) complexes.

The reaction of a molybdenum(VI) oxido imido complex with the strong Lewis acid B(C₆F₅)₃ gave access to the Lewis adduct [Mo{OB(C₆F₅)₃}(NtBu)L₂] featuring reversible B−O bonding in solution. The resulting frustrated Lewis pair (FLP)‐like reactivity is reflected by the compound's ability to heterolytically cleave Si−H bonds, leading to a clean formation of the novel cationic Mo^VI species 3 a (R=Et) and 3 b (R=Ph) of the general formula [Mo(OSiR₃)(NtBu)L₂][HB(C₆F₅)₃]. These compounds possess properties highly unusual for molybdenum d⁰ species such as an intensive, charge‐transfer‐based color as well as a reversible redox couple at very low potentials, both dependent on the silane used. Single‐crystal X‐ray diffraction analyses of 2 and 4 b, a derivative of 3 b featuring the [FB(C₆F₅)₃]⁻ anion, picture the stepwise elongation of the Mo=O bond, leading to a large increase in the electrophilicity of the metal center. The reaction of 3 a and 3 b with benzaldehyde allowed for the regeneration of compound 2 by hydrosilylation of the benzaldehyde. NMR spectroscopy suggested an unusual mechanism for the transformation, involving a substrate insertion in the B−H bond of the borohydride anion.

Reaction of [NiCl₂(PnH)₄] (1) (PnH=6‐tert‐butyl‐pyridazine‐3‐thione) with NiCl₂ affords the binuclear paddlewheel (PW) complex [Ni₂(Pn)₄] (2). Diamagnetic complex 2 is the first example of a PW complex capable of reversibly binding and releasing NH₃. The NH₃ ligand in [Ni₂(Pn)₄(NH₃)] (2⋅NH₃) enforces major spectroscopic and magnetic susceptibility changes, thus displaying vapochromic properties (λ_max(2)=532 nm, λ_max(2⋅NH₃)=518 nm) and magnetochemical switching (2: S=0; 2⋅NH₃: S=1). Upon repeated adsorption/desorption cycles of NH₃ the PW core remains intact. Compound 2 can be embedded into thin polyurethane films (2^P) under retention of its sensing abilities. Therefore, 2 qualifies as reversible optical probe for ammonia. The magnetochemical switching of 2 and 2⋅NH₃ was studied in detail by SQUID measurements showing that in 2⋅NH₃, solely the Ni atom coordinated the NH₃ molecule is responsible for the paramagnetic behavior.