Novel diazadienes based on 1,3,4-oxadiazines: Ligands in iron carbonyl complexes and substrates in catalytic [2+2+1] cycloaddition reactions

N,N′-(4-methyl-4H-1,3,4-oxadiazine-5,6-diylidene)-bis-aniline derivatives react with Fe2(CO)9 to give dinuclear iron carbonyl complexes. One of the iron atoms is bonded symmetrically to both exocyclic imine nitrogen atoms. The second iron atom shows a side-on coordination towards the CN bond next to the oxadiazine oxygen atom. In addition, the iron atoms are connected via a metal metal bond. The same oxadiazine derivatives produce chiral spiro-lactams in a ruthenium catalyzed formal [2+2+1] cycloaddition reaction with carbon monoxide and ethylene.

Graphical abstractNovel diazadienes based on a 1,3,4-oxadiazine backbone react with Fe2(CO)9 to produce unsymmetrically coordinated dinuclear iron carbonyl complexes. The same regioselectivity is observed in ruthenium catalyzed formal [2+2+1] cycloaddition reactions of the diazadienes with ethylene and carbon monoxide leading to chiral spiro-lactams.Figure optionsDownload full-size imageDownload as PowerPoint slide