A variety of pentacycloundecane (PCUD) based cage compounds containing nitro groups were synthesized via a simple synthetic method starting with cage diones. Eight PCUDs were used for nitro functionalization. These cage diones were prepared starting with easily accessible starting materials such as 2,3-dimethylhydroquinone, 1,4-dihydroxybenzene, and cyclopentadiene. Here, we have used Diels-Alder (DA) reaction, [2 + 2] photocycloaddition, and Henry reaction as key steps. Transannular cyclization plays an important role to generate a nitro substituted cage heterocycles via base promoted reaction using nitromethane as a reagent. Some of these oxa-cage structures have been further supported by single-crystal X-ray diffraction studies. Energetic performance of the title compounds was evaluated using DFT based calculations. These bis(nitromethyl)octahydro-1H-1,3,4,6(epiethane-[1,1,2,2]tetrayl)-pentaleno[1,6-bc]furan analogues (11 b-18 b) owned the densities in the range of 1.37-1.60 g/cm 3 . All the studied compounds possess high positive enthalpy of formation (33.68-230.48 kJ/mol, except compound with dimethyl groups (16 b, À 11.38 kJ/mol) and very good thermal (T m = 99-147 °C) and kinetic stabilities. Ammonium perchlorate based various propulsion formulations suggests that these compounds could be excellent candidates in the solid rocket propulsion.

Several high-energy-density strained polycyclic compounds nitromethyl-l,3-bishomocubane (NMBHC), nitromethylene-1,3-bishomocubane (NMyBHC), and bis(nitromethyl)-1,3-bishomocubane (DNTMBHC), which were synthesized for the first time from bishomocubanone, hold potential for application as standalone fuels in liquid bipropellant systems or as additives in liquid and solid propellant formulations. DFT analysis at the B3LYP/6-31G(d) level of theory was employed to optimize the geometries of the compounds and to determine their densities, heats of formation, and various thermodynamic properties. The density specific impulse, determined by using equilibrium thermodynamics, demonstrated an improvement of 75 s for NMBHC and NMyBHC over standard hydrocarbons. The specific impulse with ammonium perchlorate showed an improvement of 25-30 s over hydroxy-terminated polybutadiene. Thermogravimetric analysis revealed that NMBHC, NMyBHC, and DNTMBHC evaporated readily with activation energies of 58.8, 69.2, and 74.5 kJ mol(-1), respectively.

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Bishomocubane based azides, triazoles and tetrazoles possess high heats of formation and specific impulse, and exhibit propulsive and explosive properties, superior to RP1 and HTPB.