Copper(II) acetylacetonate‐catalyzed Wittig olefination reactions of aldehydes with ketone‐derived N‐tosylhydrazones are reported. A series of tosylhydrazones was investigated and our results showed that the carbon number of the alkyl chain influences the E‐selecivity of the alkenes greatly. Alkenes could be obtained in moderate yields and excellent E‐selectivity when the carbon numbers were up to two. Under metal‐free conditions, triphenylphosphine was able to capture the in situ generated diazo compounds and the corresponding unsymmetrical azines were formed in good yields.magnified image
The novel high‐performance energetic material 4,4,8,8‐tetranitroadamantane‐2,6‐diyl dinitrate has been synthesized and fully characterized. The synthetic strategy features the construction of the adamantane skeleton with different functional groups at adjacent methylene carbon atoms to overcome the problems associated with the ortho effect and steric crowding, and is amenable to the synthesis of other polynitroadamantanes. The experimentally determined physical properties as well as the calculated detonation properties indicate that this compound exhibits high thermal stability (220 °C), high density (1.852 g cm–3), and excellent detonation velocities (8529 m s–1) and pressures (33.43 GPa).
Two strategies have been developed for the synthesis of 2,2,4,4,6,6-hexanitroadamantane (HNA). Both strategies used the readily available diethyl malonate and paraformaldehyde as the starting materials, and utilized acylation followed by intramolecular aldol condensation to construct the adamantane skeleton. The clean nitration to introduce the gem-dinitro groups onto the adamantane skeleton was conducted using dinitrogen pentoxide in refluxing dichloromethane in the presence of urea and 4 Å molecular sieves. The acetylation route was accomplished via 12 steps and afforded HNA in an overall yield of 4.7%, and the formylation route was achieved via 11 steps in 14% overall yield.
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