Oxy-Borylenes as Photoreductants: Synthesis and Application in Dehalogenation and Detosylation Reactions.

While the range of accessible borylenes has significantly broadened over the last decade, applications remain limited. Herein, we present tricoordinate oxy-borylenes as potent photoreductants that can be readily activated by visible light. Facile oxidation of CAAC stabilized oxy-borylenes (CAAC)(IPr Me )BOR (R=TMS, CH CH C H , CH CH (4-F)C H ) to their corresponding radical cations is achieved with mildly oxidizing ferrocenium ion.

New Reactivity Patterns in 3H-Phosphaallene Chemistry [Aryl-P=C=C(H)-tBu]: Hydroboration of the C=C Bond, Deprotonation and Trimerisation.

3H-Phosphaallenes, R-P=C=C(H)C-R' (3), are accessible in a multigram scale on a new and facile route and show a fascinating chemical reactivity. BH (SMe ) and 3 a (R=Mes*, R'=tBu) afforded by hydroboration of the C=C bonds of two phosphaallene molecules an unprecedented borane (7) with the B atom bound to two P=C double bonds. This compound represents a new FLP based on a B and two P atoms.

Aspects of Phosphaallene Chemistry: Heat-Induced Formation of 1,2-Dihydrophosphetes by Intramolecular Nucleophilic Aromatic Substitution and Photochemical Generation of Tricyclic Phosphiranes.

3H-Phosphaallenes are accessible on a new and facile route and show a fascinating chemical behavior. The thermally induced rearrangement of Mes*P═C═C(H)R' (R' = Bu, Ad) afforded by C-H activation, isobutene elimination, and C-C and P-H bond formation bicyclic 1-benzo-dihydrophosphetes () with PC heterocycles. DFT calculations suggest a mechanism with intramolecular nucleophilic aromatic substitution and replacement of an alkyl group by the nucleophilic α-C atom of the phosphaallene.

3H-Phosphaallenes Revisited: Facile Synthesis by Hydroalumination of Alkynylphosphines and β-Elimination, Stability and Trapping of Transient Species by Coordination to Transition Metal Atoms.

A facile method for the efficient synthesis of 3H-phosphaallenes, R-P=C=C(H)-R', is presented, which comprises treatment of dialkynylphosphines with dialkylaluminium hydrides (hydroalumination) and elimination of aluminium alkynides from intermediate alkenyl-alkynylphosphines. The stability of the phosphaallenes depends on steric shielding by the substituents at phosphorus (aryl or CH(SiMe ) groups). Only supermesityl compounds are persistent at room temperature in solution.

Reactions of an Aluminium/Phosphorus Frustrated Lewis Pair (FLP) with α,β-Unsaturated Carbonyl Compounds: FLPs as Efficient Two-Electron Reductants with the Formation of Enolates, a cis-Enediolate, and an Allene.

The Al/P-based frustrated Lewis pair (FLP) Mes P-C(AltBu) =C(H)Ph (1; Mes=mesityl) reacted as an efficient two-electron reductant with benzil to afford a cis-enediolate that was coordinated to the FLP through P-O and Al-O bonds and the formation of a seven-membered heterocycle (2). The phosphorus atom is oxidised from +III to +V. Similar heterocycles (3 a to 3 f) were formed if 1 was treated with various enones (acrolein, acrylate, acrylamide).