Aminimide Synthesis Using Concerted Amination Reactions of Alkenes: Scope and Mechanistic Information.

Aminimides are key intermediates in the thermal cycloadditions of suitable alkenyl-hydrazine derivatives. Substrate modifications (ß-N,N-dialkyl) allowed the isolation of these reactive intermediates, and the analysis of their stereochemistry provided support for concerted (Cope-type) hydroamination and concerted [3 + 2] aminocarbonylation reaction pathways. This work also establishes the applicability of these approaches to form complex aminimides in moderate to excellent yields.

Turning on single-molecule magnet behavior in a linear {Mn3} compound.

The synthesis, structure, and magnetic properties are reported for a new manganese compound with a mixed-valent {Mn(3)} core arranged in a linear fashion. The previously reported complex 1, [Mn(IV)(3)(dpo)(6)]·2MeCN, where H(2)dpo is (E)-1-hydroxy-1,1-diphenylpropan-2-one oxime, served as a starting point for the isolation of a {Mn(3)} compound with an analogous core arrangement through the reaction of Mn(OAc)(2)·4H(2)O, H(3)oxol ((E)-2,5-dihydroxy-2,5-dimethylhexan-3-one oxime), and NaOH in MeOH and MeCN. By using these reaction conditions, compound 2, Na[Mn(IV)(2)Mn(III)(Hoxol)(6)](n)·MeOH·H(2)O, was successfully isolated revealing a central Mn(III) ion thereby introducing structural and magnetic anisotropy to the system. The structure of 2 reveals linear trinuclear Mn(IV)-Mn(III)-Mn(IV) units connected through Na(+) ions forming a linear one-dimensional coordination polymer. The Jahn-Teller axes of each trinuclear unit are aligned parallel within the same chain and form a 75° angle between the two symmetry related chains. Magnetic susceptibility measurements of 1 and 2 in the temperature range 1.9-300 K reveal that only the reduced compound, 2, is a single-molecule magnet (SMM) largely due to the anisotropy introduced by the Jahn-Teller distortions on the Mn(III) ions, which effectively induce this magnet behavior. Weak antiferromagnetic interactions along the chains through the Na(+) cations lead to a modulation of the intrinsic properties of the Mn(IV)-Mn(III)-Mn(IV) SMMs.

A novel high-spin tridecanuclear Ni(II) cluster with an azido-bridged core exhibiting disk-like topology.

A high-spin tridecanuclear Ni(II) cluster, [Ni(II)(13)(N(3))(18)(dpo)(4)(Hdpo)(2)(H(2)hpo)(4)(H(2)O)(MeOH)] [Ni(II)(13)(N(3))(18)(dpo)(4)(Hdpo)(2)(H(2)hpo)(4)(H(2)O)(2)] (1) (Hdpo = 1-(dimethylamino)propan-2-one oxime and H(2)hpo = 1-(hydroxyamino)propan-2-one oxime) with a purely azido-bridged core, is reported with dominant ferromagnetic coupling between Ni(II) ions. The latter molecule exhibits a unique planar core topology with the largest N(3)(-):Ni(II) ratio reported to date.

Improved Cope-type hydroamination reactivity of hydrazine derivatives.

A systematic investigation on the metal-free, Cope-type hydroamination reactivity of hydrazides and analogues is reported. Optimization of the hydrazide structure resulted in more facile intramolecular reactivity and enabled intermolecular reactions of alkenes, thus providing a direct approach to polysubstituted hydrazides.

Combining oximes with azides to create a novel 1-D [NaCo(III)(2)] system: synthesis, structure and solid-state NMR.

The synthesis and structure of a novel complex with the formula [NaCo(III)(2)(dmo)(2)(mu-N(3))(3)(N(3))(2)](infinity), , are reported. Complex was synthesized from the reaction of 1-(dimethylamino)propan-2-one oxime (Hdmo), CoCl(2).6H(2)O, and NaN(3) in MeOH. It crystallizes in the monoclinic space group C2/c. The molecular structure consists of one Na(I) and two Co(III) ions bridged by two oxime ligands, two end-to-end azide and three end-on azide anions. The units are linked, forming a 1-D chain. This complex was characterized by UV-Vis spectroscopy where the data confirm the presence of low-spin Co(III) ions. Solid-state (23)Na NMR experiments indicate the presence of one magnetically unique site in the repeating unit, that sample purity in the bulk powdered form is high, and that it possesses microcrystalline order. Solid-state (59)Co NMR experiments at ultra-high field (B(0) = 21.1 T) are in agreement with the structure obtained through X-ray crystallography where the Co(III) ions are coordinated to five nitrogen atoms as well as an oxygen atom.

The tandem Cope-type hydroamination/[2,3]-rearrangement sequence: a strategy to favor the formation of intermolecular hydroamination products and enable difficult cyclizations.

The tandem hydroamination/Meisenheimer rearrangement sequence was developed to address the issue of unfavorable reaction thermodynamics for intermolecular reactions of alkenes and to improve the scope of Cope-type hydroaminations. This tandem sequence allows intermolecular reactions of N-alkyl-N-methallylhydroxyl-amines to be energetically more favorable: the N-oxide intermediate formed via Cope-type hydroamination, which can revert to the starting materials via a Cope elimination, can form a more stable neutral product via a [2,3]-Meisenheimer rearrangement. This tandem sequence also leads to increased efficiency in intramolecular systems as illustrated by syntheses of two alkaloids (coniine and norreticuline) featuring difficult hydroamination key steps.