A bioinspired, intermolecular radical Stetter reaction of α‐keto acids and aldehydes is disclosed that is contingent on a formal “radical umpolung” concept. Enabled by secondary amine activation, electrostatic recognition ensures that the α‐ketocarboxylic acids, which function as latent acyl radicals, are proximal to the in situ generated iminium salts. This photoactive contact ion pair is an electron donor–acceptor (EDA) complex, and undergoes facile single electron transfer (SET) and rapid decarboxylation prior to radical–radical recombination. Importantly, decarbonylation is mitigated by this strategy. The initial computational validation on which the process is predicated matches closely with experiment. Synergising organo‐ and photocatalysis activation principles finally expands the mechanistic and synthetic scope of the classic Stetter reaction to include α,β‐unsaturated aldehydes as acceptors.

Nests of three silanol groups are located on the internal pore surface of calcined zeolite SSZ‐70. 2D 1H double/triple‐quantum single‐quantum correlation NMR experiments enable a rigorous identification of these silanol triad nests. They reveal a close proximity to the structure directing agent (SDA), that is, N,N′‐diisobutyl imidazolium cations, in the as‐synthesized material, in which the defects are negatively charged (silanol dyad plus one charged SiO− siloxy group) for charge balance. It is inferred that ring strain prevents the condensation of silanol groups upon calcination and removal of the SDA to avoid energetically unfavorable three‐rings. In contrast, tetrad nests, created by boron extraction from B‐SSZ‐70 at various other locations, are not stable and silanol condensation occurs. Infrared spectroscopic investigations of adsorbed pyridine indicate an enhanced acidity of the silanol triads, suggesting important implications in catalysis.

Reaction of the bicyclo[1.1.0]tetrasilatetraamide Si4{N(SiMe3)Dipp}4 1 (Dipp=2,6‐diisopropylphenyl) with 5 equiv of the N‐heterocyclic carbene NHCMe4 (1,3,4,5‐tetramethylimidazol‐2‐ylidene) affords a bifunctional carbene‐coordinated four‐membered‐ring compound with a Si=N group and a two‐coordinate silicon atom Si4{N(SiMe3)Dipp}2(NHCMe4)2(NDipp) 2. When 2 reacts with 0.25 equiv sulfur (S8), two sulfur atoms add to the divalent silicon atom in plane and perpendicular to the plane of the Si4 ring, which confirms the silylone character of the two‐coordinate silicon atom in 2.

An efficient geometrical E→Z isomerisation of alkenyl silanes is disclosed via selective energy transfer using an inexpensive organic sensitiser. Characterised by operational simplicity, short reaction times (2 h), and broad substrate tolerance, the reaction displays high selectivity for trisubstituted systems (Z/E up to 95:5). In contrast to thermal activation, directionality results from deconjugation of the π‐system in the Z‐isomer due to A1,3‐strain thereby inhibiting re‐activation. The structural importance of the β‐substituent logically prompted an investigation of mixed bis‐nucleophiles (Si, Sn, B). These versatile linchpins also undergo facile isomerisation, thereby enabling a formal anti‐metallometallation. Mechanistic interrogation, supported by a theoretical investigation, is disclosed together with application of the products to the stereospecific synthesis of biologically relevant target structures.

A radical approach toward 6‐perfluoroalkylphenanthridines employs the Togni reagent or derivatives thereof as radical precursors and occurs in the absence of a transition metal. Bu4NI is applied as radical initiator and phenanthridines are formed in good to excellent yields. In contrast to the currently intensively investigated trifluoromethylation of arenes, the arene core is formed during the trifluoromethylation in this approach.