Reactions of N-vinylic phosphazenes with azodicarboxylic and acetylenic esters

Copper-catalyzed stereoselective alkylhydrazination of alkynes

An efficient copper-catalyzed stereoselective alkylhydrazination of alkynes, leading to tri-substituted (E)-alkenylhydrazines, has been developed.

Reaction of N-Vinylic Phosphazenes with α,β-Unsaturated Aldehydes. Azatriene-Mediated Synthesis of Dihydropyridines and Pyridines Derived from β-Amino Acids

Aza-Wittig reaction of N-vinylic phosphazenes (1,2 addition), derived from diphenylmethylphosphine or derived from trimethylphosphine with alpha,beta-unsaturated aldehydes, leads to the formation of 3-azatrienes through a [2 + 2]-cycloaddition-cycloreversion sequence. The presence of an alkyl substituent in position 3 of N-vinylic phosphazenes increases the steric interactions, and [4 + 2] periselectivity (1,4 addition) is observed. Reaction of azatrienes with alpha,beta-unsaturated aldehydes yields pyridines.

Synthesis and characterization of alkyl- and acyl-substituted oxime–phosphazenes

Two oxime–cyclophosphazenes were prepared from the hexakis(4-formylphenoxy)cyclotriphosphazene (2) and hexakis(4-acetylphenoxy)cyclotriphosphazene (8). The reactions of these oximes with ethyl bromide, allyl bromide, propanoyl chloride, and acriloyl chloride were studied. Hexasubstituted compounds were obtained from the reactions of hexakis{4-[(hydroxyimino)methyl]phenoxy}cyclotriphosphazene (3) with ethyl bromide (4), allyl bromide (5), and propanoyl chloride (6), however, the oxime groups on 3 rearranged to nitrile (7) in the reaction of 3 with acriloyl chloride. Hexasubstituted compounds were also obtained from the reactions of hexakis{4-[(1)-N-hydroxyethaneimidoyl]phenoxy}cyclotriphosphazene (9) with allyl bromide (11) and propanoyl chloride (12). Tetra- and penta-substituted products were obtained from the reactions of 9 with ethyl bromide (10) and acriloyl chloride (13), respectively. All products were generally obtained in high yields. The structures of the compounds were defined by elemental analysis, IR, 1H, 13C, and 31P NMR spectroscopy. Key words: hexachlorocyclotriphosphazene, phosphazene, oxime, oxime derivatives, oxime–phosphazenes.