Activation of small molecules by phosphorus biradicaloids.

The reactivity of biradicaloid [P(µ-NTer)]2 was employed to activate small molecules bearing single, double, and triple bonds. Addition of chalcogens (O2 , S8 , Sex and Tex ) led to the formation of dichalcogen-bridged P2 N2 heterocycles, except from the reaction with molecular oxygen, which gave a P2 N2 ring featuring a dicoordinated P(III) and a four-coordinated P(V) center. In formal [2πe+2πe] addition reactions, small unsaturated compounds such as ethylene, acetylene, acetone, acetonitrile, tolane, diphenylcarbodiimide, and bis(trimethylsilyl)sulfurdiimide are readily added to the P2 N2 heterocycle of the biradicaloid [P(µ-NTer)]2 , yielding novel heteroatom cage compounds. The synthesis, reactivity, and bonding of the biradicaloid [P(µ-NTer)]2 were studied in detail as well as the synthesis, properties, and structural features of all addition products.

Efficient [5 + 1]-strategy for the assembly of 1,8-naphthyridin-4(1H)-ones by domino amination/conjugate addition reactions of 1-(2-chloropyridin-3-yl)prop-2-yn-1-ones with amines.

A facile synthetic approach for the synthesis of 1,8-naphthyridine-4(1H)-one derivatives via a catalyst free and Pd-supported tandem amination sequence is developed and described. In a case of aliphatic amines reaction proceeds in a catalyst free mode, however anilines demand Pd-supported reaction conditions.

Hypersilylated cyclodiphosphadiazanes and cyclodiphosphadiazenium salts.

Starting from tris(trimethylsilyl)silane the novel 2-chloro-3,4-bis-tris(trimethylsilyl)silyl-cyclo-diphospha-diazenium-tetrachloridogallate salt (7) was prepared in a six step synthetic procedure including the synthesis of N-tris(trimethylsilyl)silyl-aminodichlorophosphine (4) and 1,3-dichloro-2,4-bis-tris(trimethylsilyl)silyl-cyclo-diphospha-diazane (5). All intermediate products along the reaction path have been isolated and fully characterized. The thermally stable cyclo-diphospha-diazenium-tetrachloridogallate (7) represents an interesting example of a binary cyclic P(III)/N four-membered heterocyclic cation, with a di- and tricoordinated P atom and a delocalized bond along the NP(+)N unit. The structures of all compounds are discussed on the basis of experimental X-ray data. Moreover, for comparison the hitherto unknown 1-chloro-3-trifluoromethanesulfonato-2,4-bis-tris(trimethylsilyl)silyl-cyclo-diphosphadiazane (6) has been synthesized and fully characterized.