Preparation, X-ray crystal structure, and chemistry of stable azidoiodinanes - Derivatives of benziodoxole

Azidoiodinanes 2 and 4a,b can be prepared from the appropriate benziodoxoles 1 and 3a,b and trimethylsilyl azide in the form of stable, crystalline compounds. A single-crystal X-ray analysis for azide 4b revealed the expected hypervalent iodine distorted T-shaped geometry with the N1-I-O bond angle of 169.5 (2) degrees. The lengths of the bonds to the iodine atom, I-N (2.18 Angstrom), I-O (2.13 Angstrom), and I-C (2.11 Angstrom), are within the range of typical single covalent bonds in organic derivatives of polyvalent iodine, while the previously reported benziodoxoles generally have an elongated I-O bond. The geometry of the I-(III)NNN fragment in 4b is similar to the literature electron diffraction data on monomeric iodine azide, IN3, in gas phase. Azidobenziodoxoles 2,4 are potentially useful reagents for direct azidation of organic substrates, such as dimethylanilines, alkanes, and alkenes. Reaction of 2 with dimethylanilines proceeds under mild conditions to afford the respective N-azidomethyl-N-methylanilines in excellent yield. Alkanes, cycloalkanes, and adamantanes react with azidobenziodoxoles 2 or 4b in the presence of radical initiators at 80-132 degrees C with the formation of tertiary alkylazides, while reaction of norbornane lends to exo-2-azidonorbornane. Under similar conditions cyclohexene is selectively azidated at the allylic position.