Organic Chemistry of Explosives

74 Polynitropolycycloalkanes

(2.028 g/cm^3 ) is higher than octanitrocubane, and so this compound, which is easier to synthe-

size, may prove a more powerful explosive than the latter from the point of view of application.

2.5 Homocubanes

Marchand and co-workers conducted extensive studies into the synthesis of polynitropolycyclic

caged compounds, including those containing: pentacyclo[5.4.0.0^2 ,^6 .0^3 ,^10 .0^5 ,^9 ]undecane,^17 −^19

pentacyclo[6.3.0.0^2 ,^6 .0^3 ,^10 .0^5 ,^9 ]undecane^17 (D 3 -trishomocubane), and pentacyclo[5.3.0.0^2 ,^6.

03 ,^10 .0^4 ,^8 ]decane^19 −^22 (1,3-bishomocubane) skeletons. TheD 3 -trishomocubane and bishomo-

cubane skeletons are less strained than cubane and so their polynitro derivatives are less

energetic but generally show higher thermal stability.

A widely used strategy for the synthesis of polynitropolycyclic caged compounds is to first

synthesize the appropriate caged polycycle to contain either di- or tri-ketone functionality,

which can subsequently be transformed into nitro orgem-dinitro functionality via the oxime.

The methods available for oxime to nitro group conversion are usually robust. Direct oxidation

of an oxime to a nitro group can be achieved with varying success using peroxyacids (Sec-

tion 1.6.1.3). Another common method uses bromination-oxidation of the oxime followed by

reductive debromination with sodium borohydride (Section 1.6.1.4). An oxime can usually

undergo direct conversion to agem-dinitro group via oxidation-nitration with red fuming nitric

acid followed byin situoxidation with hydrogen peroxide (Section 1.6.1.1). Oxidative nitration

is usually the method of choice for the conversion of an existing nitro group to agem-dinitro

group (Section 1.7).

O

Br Br

OO

O

O

O O O

O

O

X

X

Br

NO 2

Br NO 2

H

NO 2

H NO 2

NO 2

NO 2

O 2 N NO 2

K 3 Fe(CN) 6

43 44 45

48, X = O (^4746)
49, X = NOH
50 51 52
TsOH,
HOCH 2 CH 2 OH
PhH, reflux
90 %
Br 2 , dioxane
55 %
Na, MeOH
reflux
41 %
58 %
THF,
conc. HCl

1. hv, PhH, 85 %


2. H 2 SO 4 (aq)
   (49 % of 48)


3. NH 2 OH.HCl,
   NaOAc, EtOH (aq)
   (65 % of 49)

NaBH 4 ,

EtOH

70 %

(mixture of isomers) (mixture of isomers)

1. Br 2 , DMF,
   NaHCO 3


2. TFAA,
   H 2 O 2

24 % (2 steps)

42

[2+4]-cyclo-

addition

NaOH, NaNO 2

65 %

OO OO

Figure 2.13