Preparation and Structure of Novel Hexaazaisowurtzitane Cages

Abstract

Hexaazaisowurtzitane or cage molecules have attracted attention concerning their synthesis because hexanitrohexaazaisowurtzitane (HNIW or CL20) is presently the most powerful energetic compound. The synthesis of hexaazaisowurtzitanes was considered to be limited solely to the condensation of certain benzylamines with glyoxal. Here, we present the synthesis and characterization of seven novel non-benzylic hexaazaisowurtzitanes, such as hexapropargylhexaazaisowurtzitane. The substituents on the six nitrogen atoms are different to those of the benzyl or substituted benzyl groups to which previous syntheses were limited. X-ray structures are given for the hexapropargyl and hexa-2-thienylmethylene derivatives. Steric strains limit the synthesis with alpha-substituted benzyl and allyl derivatives. The reaction mechanism and the role of the intermediate diimines are discussed. Some of the novel hexaazaisowurtzitanes are potential precursors of hexanitrohexaazaisowurtzitane.

Accelerated synthesis of energetic precursor cage compounds using confined volume systems

“…Figure 5 compares the CR for the spray-based techniques across all amines. Overall, the CR are better for AA and CPrA, of which AA has been previously reported in the literature to form the cage structure 57 , 58 . The larger amines in the series (CBA, CPA, and CHA) show a drastic drop in CR (< 20% conversion).…”

Synthesis of Novel Hexaazaisowurtzitane Cages to Access CL‐20

“…In 2 a , two singlets for the two types of cage ring methine protons observed in a 4 : 2 ratios at around δ=3.99 and 4.13 ppm and for 2 b δ=3.66 and 3.84 ppm (Table 5). The unique feature of these molecules is that the nitrogen is directly linked to methine (−CH) system and it is unlike so far the reported isowurtzitane cage products; in which nitrogen is directly connected to methylene (−CH 2 ) system [4,5,8] . Therefore, these compounds are easily detectable by the signals of neighboring methine protons ( 2 a at δ=2.39–2.62 ppm and 2 b at 3.70–3.76 ppm) in a 4 : 2 ratios (Table 5).…”

“…Therefore researchers have been keen to replacing benzylamine in order to avoid the expensive and sensitive step of catalytic hydrogenolysis on HBIW in the synthesis of CL‐20 [7] . Despite these challenges, in 2006, the Herve group reported the formation of a hexaazaisowurtzitane cage formation with activated amines such as thienylamine, pyridylamine, furfurylamine, naphthylamine, cinnamylamine, allylamine and propargylamine (Scheme 1b) [8] . Unfortunately, the isolation and purification of resulting products are cumbersome when using these substrates except for hexaallylhexaazaisowurtzitane (HAIW) [9] .…”

One-Pot Synthesis of Hexaacetylhexaazaisowurtzitane (HAIW) a Precursor of 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (HNIW-CL−20)

“…The recent publications by many researchers are explored the synthesis of CL‐20 without heavy‐metal (palladium) catalyst as well as benzylamine. In all the reports, they have utilized hexaallylhexaazaisowurtzitane (HallylIW) as a precursor for synthesis of CL‐20.…”