Michael M. Bobek

Structure−Reactivity Relationships: Reactions of a 5-Substituted Aziadamantane in a Resorcin[4]arene-based Cavitand

The complexation properties of two novel C5-substituted adamantanediazirines within the resorcin[4]arene-based cavitand 4 were investigated in DMSO-d(6), revealing that binding is up to 1.4 kcal/mol stronger for halogenated adamantanediazirines when compared with the unsubstituted species. The thermal behavior of 5-bromo-2-aziadamantane (3) was investigated by DSC analysis as the first representative of the adamantanediazirine family in the neat solid state, as well as encapsulated within the aromatic cavity of cavitand 4. In the solid phase, the reactions of photolytically or thermolytically generated 5-bromo-2-adamantanylidene (11) can be controlled by complexation within cavitand 4.

4-Aziadamantan-1-amine: synthesis, reactions and cyclodextrin complexes

A new and potentially therapeutic diazirine, 4-aziadamantan-1-amine, was synthesized. Structural characterization also included single crystal X-ray diffraction analysis. Photolysis of the title compound in the solid phase afforded an azine. In contrast, pyrolysis in the gas phase gave two intramolecular carbene insertion products in a 4:1 ratio. A rationale for the observed diastereoselectivity is offered based upon ab initio calculations. Finally, inclusion compounds of the title compound with α- and β-cyclodextrin were prepared. A 2:1 complex bearing two hosts was formed with α-cyclodextrin and a 1:1 complex was obtained with β-cyclodextrin. The association constants were determined via induced circular dichroism (ICD) analysis.

Intra- and intermolecular reaction selectivities of γ-substituted adamantanylidenes.

A study of adamantanylidenes having a γ-substituent (R) was undertaken to gauge how inductive and steric effects of remotely positioned functional groups influence intra- and intermolecular product selectivity. 3H-Diazirines were thermolyzed or photolyzed to generate the corresponding carbenes. On rapid heating, the resulting carbenes isomerized to 2,4-didehydroadamantanes by intramolecular 1,3-CH insertions. When R was an electron donor (R(D)) mostly asymmetric 1-substituted derivatives were produced but when it was an electron acceptor (R(A)) the symmetric 7-substituted ones were formed. When solutions were exposed to UV-A light, intermolecular adducts from the carbenes and solvent predominated with lesser amounts of intramolecular product being formed. Valence isomerization of 3H-diazirines also afforded diazo compounds. In methanol, protonation of diazo compounds to give the corresponding 2-adamantyl cations exceeds their coupling. This diversion was controlled with fumaronitrile by trapping the diazo compounds. The adducts possessed mostly anti configurations with R = R(D) and syn arrangements with R = R(A). The connection between as- and anti-product formation and that of s- and syn-products was deemed to be the consequence of a rapid equilibrium between two distinct carbene conformations. This was qualified and quantified using ab initio calculations and NBO analyses.

A ‘sugar-coated’ carbene precursor: a single crystal X-ray diffraction and NMR study†

For the first time, the inclusion complex of any diazirine with a cyclodextrin was studied by single crystal X-ray diAraction. This and 2D NMR spectroscopy were employed to elucidate the structure in both the solid state and solution. An opposite orientation of the guest inside the host molecule was revealed. Moreover, crystallization of the neat guest enabled the first X-ray diAraction of a dialkyl-substituted diazirine. # 2000 Published by Elsevier Science Ltd.

A Facile One-Step Synthesis of 2,4-Adamantanedione

Abstract 2,4-Adamantanedione (2) can be synthesized in one step by direct oxidation of adamantanone with a pyridine-chromium trioxide complex in acetic anhydride in 54% isolated yield.